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Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 11 Biotechnology: Principles and Processes. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Biotechnology: Principles and Processes MCQs Pdf with Answers to know their preparation level.

Biotechnology: Principles and Processes Class 12 Biology MCQs Pdf

1. Biolistics (gene gun) is suitable for
(a) introducing rDNA into plant cells
(b) introducing rDNA into animal cells
(c) disarming the pathogen vectors
(d) DNA fingerprinting.

Answer

Answer: a

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2. In genetic engineering experiments, restriction enzymes are used for
(a) viral DNA
(b) bacterial DNA
(c) eukaryotic DNA
(d) any type of DNA.

Answer

Answer: b

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3. The DNA fragments produced by the use of restriction endonucleases can be separated by
(a) polymerase chain reaction
(b) gel electrophoresis
(c) density gradient centrifugation
(d) any of the above.

Answer

Answer: b

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4. Plasmids in bacterial cells are
(a) extra-chromosomal DNA, which cannot replicate
(b) extra-chromosomal DNA, which can . self-replicate
(c) extra DNA associated with the genome
(d) extra DNA, associated with the genome, but cannot replicate.

Answer

Answer: b

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5. The DNA polymerase enzyme used in PCR is obtained from
(a) Thermus aquaticus
(b) Escherichia coli
(c) Agrobacterium tumefaciens
(d) Salmonella typhimurium.

Answer

Answer: a

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6. While isolating DNA from bacteria, which of the following enzymes is not used? [NCERT Exemplar]
(a) Lysozyme
(b) Ribonuclease
(c) Deoxyribonuclease
(d) Protease

Answer

Answer: a

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7. Significance of ‘heat shock’ method in bacterial transformation is to facilitate [NCERT Exemplar]
(a) binding of DNA to the cell wall
(b) uptake of DNA through membrane transport proteins
(c) uptake of DNA through transient pores in the bacterial cell wall
(d) expression of antibiotic resistance gene

Answer

Answer: c

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8. Which of the following steps are catalysed by Taq polymerase in a PCR reaction? [NCERT Exemplar]
(a) Denaturation of template DNA
(b) Annealing of primers to template DNA
(c) Extension of primer end on the template DNA
(d) All of the above

Answer

Answer: c

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9. Which of the given statement is correct in the context of observing DNA separated by agarose gel electrophoresis? [NCERT Exemplar]
(a) DNA can be seen in visible light
(b) DNA can be seen without staining in visible light
(c) Ethidium bromide stained DNA can be seen in visible light
(d) Ethidium bromide stained DNA can be seen under exposure to UV light

Answer

Answer: d

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10. ‘Restriction’ in Restriction enzyme refers to [NCERT Exemplar]
(a) cleaving ofphosphodiester bond in DNA by the enzyme
(b) cutting of DNA at specific position only
(c) prevention of the multiplication of bacteriophage in bacteria
(d) all of the above

Answer

Answer: c

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11. The role of DNA ligase in the construction of a recombinant DNA molecule is [NCERT Exemplar]
(a) formation of phosphodiester bond between two DNA fragments
(b) formation of hydrogen bonds between sticky ends of DNA fragments
(c) ligation of all purine and pyrimidine bases
(d) none of the above

Answer

Answer: b

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12. In an experiment, recombinant DNA bearing ampicillin-resistance gene is transferred into E.coli cells. The host cells are then cultured on a medium containing ampicillin. The result will be
(a) both transformants and non-transformants cannot survive.
(b) both transformants and non-transformants can survive.
(c) transformants only and not the non-transformants can survive.
(d) transformants cannot survive, but non-transformants can not.

Answer

Answer: c

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13. The _______ in a vector helps in identifying the transformants and eliminating the non-transformants.

Answer/Explanation

Answer:
Explaination: Selectable marker.

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14. When the enzyme _______ is inactivated in E.coli, the transformants do not produce any colour in the presence of a chromogenic substrate.

Answer/Explanation

Answer:
Explaination: β-galactosidase.

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15. _______ is the method of bombarding high velocity microparticles of gold or tungsten coated with DNA, into plant cells.

Answer/Explanation

Answer:
Explaination: Biolistics/gene gun.

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16. To isolate DNA from fungal cells for biotechnology experiments, enzyme _______ is necessary.

Answer/Explanation

Answer:
Explaination: Chitinase.

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17. _______ is used as cloning vector for transformation in plant cells.

Answer/Explanation

Answer:
Explaination: Agmbacterium.

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18. Downstream processing involves separation and _______ .

Answer/Explanation

Answer:
Explaination: Purification.

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19. _______ is the process of extraction of DNA from the separated bands of DNA in agarose gel.

Answer/Explanation

Answer:
Explaination: Elution.

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20. _______ gene in the E.coli vector, pBR 322 codes for enzymes/proteins involved in the replication of the plasmid.

Answer/Explanation

Answer:
Explaination: Rop.

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21. _______ are the E.coli enzymes that remove the nucleotides from the ends of DNA strands.

Answer/Explanation

Answer:
Explaination: Exonucleases.

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22. _______ is an autonomously replicating, circular, extra-chromosomal DNA in bacterial cells.

Answer/Explanation

Answer:
Explaination: Plasmid.

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23. Match the items in Column I with those in Column II.

Column I	Column II
A. Sea weeds	1. Gel electrophoresis
B. Staining of DNA	2. Source of Agarose
C. Separation of DNA fragments	3. Isolation of DNA from the gel
D. Elution	4. Ethidium bromide

Answer/Explanation

Answer:
Explaination: A – 2, B – 4, C – 1, D – 3

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24. Match the Column l with the Column II.

Column I	Column II
A. Competent host	1. Separation and purification
B. Cloning vector	2. Culturing of cells in large volumes
C. Downstream processing	3. Taq polymerase
D. PCR	4. Divalent cation (Ca2+)
E. Bioreactor	5. pBR 322
	6. Gel electrophoresis

Answer/Explanation

Answer:
Explaination: A – 4, B – 5, C – 1, D – 3, E – 2

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25. Since DNA fragments are positively charged they move towards the anode. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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26. Agarose, the most commonly used matrix in gel electrophoresis is obtained from fungi. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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27. The DNA fragments separate according to their size through agarose gel during electrophoresis. [True/False]

Answer/Explanation

Answer:
Explaination: True.

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28. The cloning vector pBR 322 has three antibiotic-resistance genes. [True/False]

Answer/Explanation

Answer:
Explaination: False.

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29. The vector DNA and foreign DNA are cut by the same restriction endonuclease. [True/False]

Answer/Explanation

Answer:
Explaination: True.

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Directions (Q30 to Q32): Mark the odd one in each of the following groups.
30. Cellulose, Lysozyme, Chitinase, Endonuclease

Answer/Explanation

Answer:
Explaination: Endonuclease.

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31. Hind III, EcoRI, Sal I, Rop

Answer/Explanation

Answer:
Explaination: Rop.

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32. Denaturation, Elution, Annealing, Extension

Answer/Explanation

Answer:
Explaination: Elution.

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33. How has European Federation of Biotechnology (EFB) defined biotechnology?

Answer/Explanation

Answer:
Explaination: The European Federation of Biotechnology defines biotechnology as the integration of natural science and organisms, cells or parts thereof and molecular analogues, for products and services; it encompasses both .traditional and modem molecular biology.

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34. Name the technique that is used to alter the chemistry of genetic material (DNA/RNA) to obtain the desired result. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: Genetic engineering.

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35. What is meant by gene cloning?

Answer/Explanation

Answer:
Explaination: Gene cloning refers to the process in which a numer of identical copies of a gene of interest are made by introducing the gene into an appropriate host using a suitable Vector.

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36. Why is it not possible for an alien DNA to become part of a chromosome anywhere along its length and replicate normally? [AI 2014]

Answer/Explanation

Answer:
Explaination: The alien DNA has to be linked to a specific sequence of DNA, called origin of replication, on the chromosome; this origin of replication is responsible for initiation of replication.

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37. Name the specific sequence of DNA in a plasmid that the ‘gene of interest’ ligates with, to enable it to replicate. [AI 2013C]

Answer/Explanation

Answer:
Explaination: Origin of replication (Ori)

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38. Write the two components of the first artificial recombinant DNA molecule constructed by Cohen and Boyer. [Foreign 2014]

Answer/Explanation

Answer:
Explaination: An antibiotic-resistance gene and the plasmid of Salmonella typhimurium.

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39. Name the two enzymes that are essential for constructing a recombinant DNA. [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: Restriction endonuclease and DNA ligase.

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40. In the year 1963, two enzymes responsible for restricting the growth of bacteriophage in E.coli were isolated. How did the enzymes act to restrict the growth of the bacteriophage? [AI 2011C]

Answer/Explanation

Answer:
Explaination:
– One of them (exonucleases) added methyl groups to DNA.
– The other (endonucleases) cut the DNA at specific points within the DNA.

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41.Name the enzyme that helps to join DNA fragments. [AI 2017C]

Answer/Explanation

Answer:
Explaination: DNA ligase

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42. Mention the role of Restriction enzyme in Recombinant DNA technology. [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: They act as molecular scissors to cut DNA at specific locations.

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43. What does ‘R’ stand for, in the restriction endonuclease, EcoRI?

Answer/Explanation

Answer:
Explaination: R stands for RY 13, the strain of E.coli bacterium.

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44. A plasmid and a DNA sequence in a cell need to be cut for producing recombinant DNA. Name the enzyme that acts as molecular scissors to cut the DNAs.

Answer/Explanation

Answer:
Explaination: Restriction endonucleases.

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45. Suggest a technique to a researcher who needs to separate fragments of DNA. [Delhi 2016]

Answer/Explanation

Answer:
Explaination: Gel electrophoresis.

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46. Name the material used as matrix in gel electrophoresis and mention its role. [AI 2014C]

Answer/Explanation

Answer:
Explaination: Agarose; it provides the sieving effect for the DNA to resolve according to their size.

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47. Why do DNA-fragments move towards the anode during gel electrophoresis? [CBSE 2018C, Delhi 2011C; HOTS]

Answer/Explanation

Answer:
Explaination: DNA-fragments are negatively charged and hence, move towards the anode.

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48. What is the role of ethidium bromide during agarose-gel electrophoresis of DNA fragments?

Answer/Explanation

Answer:
Explaination: The gel is stained by ethidium bromide, to view the separated DNA bands when exposed to UV light.

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49. Which main technique and instrument is used to isolate DNA from a plant cell? [CBSE Sample Paper 2013, 2014]

Answer/Explanation

Answer:
Explaination:
– Centrifugation is the technique.
– Centrifuge is the instrument.

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50. Name two commonly used vectors for genetic engineering.

Answer/Explanation

Answer:
Explaination: Plasmids and bacteriophages.

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51. Why are engineered vectors preferred these days?

Answer/Explanation

Answer:
Explaination:
(i) Engineered vectors facilitate easy linking of foreign DNA.
(ii) They help in selection of recombinants.

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52. Mention the uses of cloning vectors in biotechnology. [Delhi 2011]

Answer/Explanation

Answer:
Explaination:
(i) Cloning vectors are used to make multiple copies of the desired DNA/ gene.
(ii) They are used to transfer the gene of interest to the host cell.

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53. Why is ‘plasmid’ an important tool in biotechnology experiments? [AI2013C]

Answer/Explanation

Answer:
Explaination: Since plasmids can replicate within the bacterial cell independently of the genomic DNA, any alien DNA ligated to it will also multiply, i.e. it is used as a vector as well as in gene cloning.

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54. Why is it essential to have a ‘selectable marker’ in a cloning vector? [AI 2010; HOTS]

Answer/Explanation

Answer:
Explaination: It helps in identifying the recombinants from the non-recombinants.

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55. Why are antibiotic-resistance genes used as markers in E.coli? [HOTS]

Answer/Explanation

Answer:
Explaination: It is because the normal E. coli cells do not have resistance to any such antibiotics.

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56. Name two antibiotic-resistance genes in the pBR 322 of E.coli plasmid.

Answer/Explanation

Answer:
Explaination: Ampicillin-resistance gene and tetracyclin- resistance gene.

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57. A plasmid without a selectable marker was chosen as vector for cloning a gene. How does this affect the experiment? [HOTS]

Answer/Explanation

Answer:
Explaination: In the absence of a selectable marker, it will not be possible to identify the recombinants from the non-recombinants.

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58. State what happens when an alien gene is ligated at Sal I site of pBR 322 plasmid. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: The transformant loses the tetracycline- resistance.

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59. State what happens when an alien gene is ligated at Pvu I site of pBR 322 plasmid. [AI 2013C]

Answer/Explanation

Answer:
Explaination: The transformant loses ampicillin-resistance.

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60. How is Agrobacterium tumefaciens able to transform a normal plant cell into a tumour? [Delhi 2013C]
Or
Biotechnologists refer to Agrobacterium tumefaciens as a natural genetic engineer of plants. Give reasons to support the statement. [AI 2011]

Answer/Explanation

Answer:
Explaination: When it infects a plant cell, it delivers a part of its DNA, called ‘T-DNA’ (or Tumour- inducing (Ti) plasmid) into the plant cell and transforms it into a tumour cell.

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61. How can retroviruses be used efficiently in biotechnology experiments in spite of them being disease causing? [AI 2013C]

Answer/Explanation

Answer:
Explaination: Retroviruses are disarmed (diseases-causing gene is removed/inactivated) and used as vectors to deliver the recombinant/alien DNA into animal cells.

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62. Name the commonly used vector for transformation in plant cells.

Answer/Explanation

Answer:
Explaination: Agrobacterium tumefaciens.

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63. How does an alien DNA gain entry into a plant cell by ‘biolistic’ method? [Foreign 2013]

Answer/Explanation

Answer:
Explaination: The cells are bombarded with high velocity micro-particles of gold or tungsten, coated with the alien DNA.

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64. Mention the type of host cells suitable for the gene guns to introduce an alien DNA. [Delhi 2014]

Answer/Explanation

Answer:
Explaination: Plant cells.

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65. Name the host cells in which micro-injection technique is used to introduce an alien DNA. [Foreign 2014]

Answer/Explanation

Answer:
Explaination: Animal cells.

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66. Why is the enzyme cellulase needed for isolating genetic material from plant cells and not from animal cells? [Delhi 2013, 2010; HOTS]

Answer/Explanation

Answer:
Explaination: Cellulase is used to digest the cell wall (cellulose) of plant cells; animal cells have no cell wall and hence, it is not needed.

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67. How can bacterial DNA be released from the bacterial cell for biotechnology experiments? [Delhi 2011]

Answer/Explanation

Answer:
Explaination: The bacterial cell has to be treated with lysozyme, to digest the cell wall to release DNA.

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68. To use the restriction enzyme to cut the DNA, the DNA must be in a pine form, i.e. free from proteins and RNAs associated with it. How is it achieved?

Answer/Explanation

Answer:
Explaination:
– Proteins are removed by using proteases.
– RNAs are removed by using ribonucleases (RNases).

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69. Write the names of the enzymes that are used for isolation of DNA from bacterial and fungal cells, respectively for Recombinant DNA technology. [AI, Foreign 2014]

Answer/Explanation

Answer:
Explaination:
– Lysozymes for bacterial cells.
– Chitinase for fungal cells.

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70. Write the importance of the bacterium Thermus aquaticus in polymerase chain reaction. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: It is the source of thermostable DNA- polymerase enzyme.

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Free PDF Download of CBSE Chemistry Multiple Choice Questions for Class 12 with Answers Chapter 16 Chemistry in Everyday Life. Chemistry MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Chemistry in Everyday Life MCQs Pdf with Answers to know their preparation level.

Chemistry in Everyday Life Class 12 Chemistry MCQs Pdf

Chemistry MCQS for Class 12 Question 1. Which of the following is used as tranquilizer?
(a) Naproxene
(b) Tetracycline
(c) Chlorpheniramine
(d) Equanil

Answer/Explanation

Answer: d
Explaination: (d) Equanil.

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2. Which one of the following is antihistamine?
(a) Chloramphenicol
(b) Diphenyl hydramine
(c) Norethindrone
(d) Omeprazole

Answer/Explanation

Answer:
Explaination:
(b) (a) is broad spectrum antibiotic
(c) is ’ antifertility drug (birth control) and
(d) is antacid.

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3. Artificial sweetener which is stable only under cold conditions only is
(a) saccharine
(b) sucralose
(c) aspartame
(d) alitame

Answer/Explanation

Answer: c
Explaination: (c) aspartame.

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Chemistry MCQS for Class 12 with Answers Pdf Question 4. Bithional added to soap acts as
(a) buffering agent
(b) antiseptic
(c) softener
(d) drying

Answer/Explanation

Answer: b
Explaination: (b) antiseptic.

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5. .Which of the following is analgesic?
(a) Streptomycin
(b) Chloromycetin
(c) Novalgin
(d) Penicillin

Answer/Explanation

Answer: c
Explaination: (c) is analgesic (pain reliever) others are antibiotics.

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6. Mixture of chloroxylenol and terpineol acts as
(a) antiseptic
(b) antipyretic
(c) antibiotic
(d) analgesics

Answer/Explanation

Answer: a
Explaination: (a) These are components of Dettol.

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Class 12 Chemistry MCQ Pdf Question 7. Which of the following is used as antacid?
(a) Iproniazid
(b) Salvarsan
(c) Zantac
(d) Chloramphenicol

Answer/Explanation

Answer:
Explaination:
(c) Zantac is antacid,
(b) is used for treatment of syphilis,
(a) is tranquilizer and
(d) is broad spectrum antibiotic.

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8. Drugs that bind to receptor site and inhibit its natural function are called
(a) antagonists
(b) agonists
(c) enzymes
(d) molecular targets

Answer/Explanation

Answer: a
Explaination: (a) These are called antagonists.

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9. The drug Tagamet is
(a) analgesics
(b) antidepressant
(c) anaesthetic
(d) antacid

Answer/Explanation

Answer: d
Explaination: (d) antacid.

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10. Which of the following cationic detergent?
(a) Sodium lauryl sulphate.
(b) Cetyl trimethyl ammonium bromide.
(c) Sodium dodecyl benzene sulphonate.
(d) Glyceryl oleate.

Answer/Explanation

Answer:
Explaination:
(b) (a) and (c) are anionic detergents and
(d) is fat (glycerol ester of fatty acid).

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11. The artificial sweetener which contains chlorine that has the appearance and taste as that of sugar and is stable and cooking temperature:
(a) Aspartame
(b) Saccharin
(c) Sucralose
(d) Alitame

Answer/Explanation

Answer: c
Explaination: (c) Sucralose

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12. Narcotic analgesic is
(a) aspirin
(b) paracetamol
(c) codeine
(d) cimetidine

Answer/Explanation

Answer:
Explaination:
(c). (a) and (b) are analgesics and antipyretic
(d) is antacid.

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13. Bactericidal antibiotic among the following is
(a) ofloxacin
(b) erythromycin
(c) chloramphenicol
(d) tetracycline

Answer/Explanation

Answer: a
Explaination:
(a) is bactericidal, others are bacteriostatic, i.e., suppress the multiplication of bacteria.

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14. Butylated Hydroxy Toluene (BHT) as a food additive acts as
(a) antioxidant
(b) flavouring agent
(c) colouring agent
(d) emulsifier

Answer/Explanation

Answer: a
Explaination: (a) It prevents spoilage of butter.

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15. Sodium benzoate is used as
(a) food preservative
(b) artificial sweetener
(c) antioxidant
(d) detergent

Answer/Explanation

Answer: a
Explaination: (a) It is food preservative, used in cold drinks.

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16. Which of the following is not an antacid?
(a) Phenelzine
(b) Ranitidine
(c) Al(OH)₃
(d) Cimetidine

Answer/Explanation

Answer: a
Explaination:
(a) Phenelzine is antidepressant (tranquilizer), not an antacid, others are antacids.

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17. Allergy is caused by the production of in the body
(a) Hormones
(b) Enzymes
(c) Vitamins
(d) Histamines

Answer

Answer: d

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18. Which of the following can possibly be used as analgesic without causing addiction and modification?
(a) Morphine
(b) Diazepam
(c) N-acety 1-para-aminophenol
(d) LSD

Answer

Answer: c

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Chemistry MCQ with Answers Class 12 Question 19. Aspiring is an acetylation product of ______
(a) p-Dihydroxybenzene
(b) o-Hydroxybenzoic acid
(c) o-Dihydroxy benzene
(d) m-Hydroxy benzoic acid

Answer

Answer: b

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20. Drug which is used to reduce anxiety and brings calmness is known as
(a) Tranquilizer
(b) Diuretic
(c) Analgesic
(d) Antacids

Answer

Answer: a

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21. Which element is not present in Saccharin, an artificial sweetner?
(a) C
(b) P
(c) S
(d) N

Answer

Answer: b

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22. Heroin is
(a) Narcotic
(b) Non-narcotic
(c) Anaesthetic
(d) Antiseptic

Answer

Answer: a

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23. Detergents are better than soaps because
(a) They are less affected by hard water
(b) They can be used in acidic solution
(c) Both (a) and (b)
(d) They wash clothes better

Answer

Answer: c

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24. Which one is a broad spectrum drug?
(a) Chloramphenicol
(b) Chloroquine
(c) Chloroxylenol
(d) Plasmoquine

Answer

Answer: a

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25. A drug that is antiseptic as well as analgesic is
(a) Para acetamidophenol
(b) Chloropromazine hydrochloride
(c) Chloramphenicol
(d) Paracetamol

Answer

Answer: a

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Chemistry MCQS for Class 12 Chapter wise Pdf Question 26. Match List-I with List-II and select the correct answer using the code given below in the Lists.

(a) 1 -(a), 2-(c), 3-(d), 4-(e)
(b) 1 -(b), 2-(a), 3-(d), 4-(e)
(c) 1 -(b), 2-(c), 3-(e), 4-(d)
(d) 1 -(b), 2-(a), 3-(d), 4-(e)

Answer

Answer: d

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27. A narrow spectrum antibiotic is active against __________ .[NCERT Exemplar]
(a) gram positive or gram negative bacteria.
(b) gram negative bacteria only.
(c) single organism or one disease.
(d) both gram positive and gram negative bacteria.

Answer/Explanation

Answer: a
Explaination:
(a) is correct statement.

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28. Which of the following enhances leathering property of soap? [NCERT Exemplar]
(a) Sodium carbonate
(b) Sodium rosinate
(c) Sodium stearate
(d) Trisodium phosphate

Answer/Explanation

Answer: b
Explaination:
(b) Sodium rosinate enhance lathering property of soap.

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29. Glycerol is added to soap. It functions __________ . [NCERT Exemplar]
(a) as a filler.
(b) to increase leathering.
(c) to prevent rapid drying.
(d) to make soap granules.

Answer/Explanation

Answer: c
Explaination:
(c) It prevents rapid drying because it is hygroscopic (absorbs moisture) from atmosphere.

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30. Which of the following is an example of liquid dish-washing detergent? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(b) is dishwashing, non-ionic detergent,
(d) Cationic,
(a) and (c) are anionic detergents.

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31. Which of the following is not a target molecule for drug function in body? [NCERT Exemplar]
(a) Carbohydrates
(b) Lipids
(c) Vitamins
(d) Proteins

Answer/Explanation

Answer: c
Explaination:
(c) Vitamins are not a target molecules for drug function in body.

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Note: In the following questions two or more options may be correct. (Q.22 to Q.25)
32. Which of the following statements are incorrect about receptor proteins? [NCERT Exemplar]
(а) Majority of receptor proteins are embedded in the cell membranes.
(b) The active site of receptor proteins opens on the inside region of the cell.
(c) Chemical messengers are received at the binding sites of receptor proteins.
(d) Shape of receptor doesn’t change during attachment of messenger.

Answer/Explanation

Answer:
Explaination:
(b) and (d) are incorrect.

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33. Which of the following statements are correct about barbiturates? [NCERT Exemplar]
(a) Hypnotics or sleep producing agents.
(b) These are tranquilizers.
(c) Non-narcotic analgesics.
(d) Pain reducing without disturbing the nervous system.

Answer/Explanation

Answer:
Explaination:
(a) and (b) are correct.

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34. Compounds with antiseptic properties are __________ . [NCERT Exemplar]
(a) CHCl₃
(b) CHI₃
(c) Boric acid
(d) 0.3 ppm aqueous solution of Cl₂

Answer/Explanation

Answer:
Explaination:
(b) CHI₃ (Iodoform) and
(c) Boric acid are antiseptics.

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35. Which of the following statements are [NCERT Exemplar]
(a) An antibacterial fungus.
(b) Ampicillin is its synthetic modification.
(c) It has bacteriostatic effect. soap bubbles .
(d) It is a broad spectrum antibiotic.

Answer/Explanation

Answer:
Explaination:
(c) and (d) are incorrect. It is bactericidal.

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36. Match the medicines given in Column I with their use given in Column II. [NCERT Exemplar]

Column I	Column II
(a) Ranitidine	(i) Tranquilizer
(b) Furacine	(ii) Antibiotic
(c) Phenelzine	(iii) Antihistamine
(d) Chloramphenicol	(iv) Antiseptic
	(v) Antifertility drug

Answer/Explanation

Answer:
Explaination:
(a) (iii)
(b) (iv)
(c) (i)
(d) (ii)

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37. Match the soaps given in Column I with incorrect about penicillin? items given in Column II. [NCERT Exemplar]

Column I	Column II
(a) Soap chips	(i) dried miniature
(b) Soap granules	(ii) small broken pieces of soap formed from melted soaps
(c) Soap powder	(iii) soap powder + abrasives + builders (Na2CO3, Na3PO4)
(d) Scorning soap	(iv) soap powder + builders like Na2CO3 and Na3PO4

Answer/Explanation

Answer:
Explaination:
(a) (ii)
(b) (i)
(c) (iv)
(d) (iii)

---

38. Match the class of compounds given in Column I with their functions given in Column II. [NCERT Exemplar]

Column I	Column II
(a) Antagonists	(i) Communicate message between two neurons and that between neurons to muscles
(b) Agonists	(ii) Bind to the receptor site and inhibit its natural function
(c) Chemical messenger	(iii) Crucial to body’s communication process
(d) Inhibitors	(iv) Mimic the natural messenger
(e) Receptors	(v) Inhibit activities of enzymes.

Answer/Explanation

Answer:
Explaination:
(a) (ii)
(b) (iv)
(c) (i)
(d) (v)
(e) (iii)

---

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (Q.29 to Q.32)
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct but reason is wrong statement.
(d) Assertion is wrong but reason is correct statement.
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.
39. Assertion: Sulpha drug contain sulphonamide group. [NCERT Exemplar]
Reason: Salvarsan is a sulpha drug.

Answer/Explanation

Answer: c
Explaination:
(c) Assertion is correct but reason is wrong statement.

---

40. Assertion: Transparent soaps are made by dissolving soaps in ethanol. [NCERT Exemplar]
Reason: Ethanol makes things invisible.

Answer/Explanation

Answer: c
Explaination:
(c) Assertion is correct but reason is wrong statement.

---

41. Assertion: Competitive inhibitors compete with natural substrate for their attachment on the active sites of enzymes. [NCERT Exemplar]
Reason: In competitive inhibition, inhibitor binds to the allosteric site of the enzyme.

Answer/Explanation

Answer: c
Explaination:
(c) Assertion is correct but reason is wrong statement.

---

42. Assertion: Non-competitive inhibitor inhibits the catalyic activity of enzyme by binding with its active site. [NCERT Exemplar]
Reason: Non-competitive inhibitor changes the shape of the active site in such a way that substrate can’t recognise it.

Answer/Explanation

Answer: d
Explaination:
(d) Assertion is wrong but reason is correct statement.

---

43. Histamine is potent __________ .

Answer/Explanation

Answer:
Explaination: vasodilator.

---

44. __________ prevents heart attack, can also be used as analgesics and antipyretic but should not be taken empty stomach as it releases salicylic acid, may damage stomach lining.

Answer/Explanation

Answer:
Explaination: Aspirin.

---

45. Plenty of salt and cover of oil act as __________ .

Answer/Explanation

Answer:
Explaination: preservative.

---

46. Bathing soaps are __________ salts of long chain fatty acids.

Answer/Explanation

Answer:
Explaination: potassium.

---

47. Aspirin is not suitable for ulcer patients. [True\False]

Answer/Explanation

Answer:
Explaination:
True, it forms salicylic acid which may cause bleeding and wounds.

---

48. cis-platin is used in chemotherapy for cancer. [True\False]

Answer/Explanation

Answer:
Explaination:
True, it is antitumour agent.

---

49. A person suffering from depression has low level of noradrenaline. [True\False]

Answer/Explanation

Answer:
Explaination: True.

---

50. Morphine is narcotic analgesics given in acute pain of terminal cancer. [True\False]

Answer/Explanation

Answer:
Explaination:
True, it causes addiction, should not be used regularly

---

51. Which site of an enzyme is called allosteric site?

Answer/Explanation

Answer:
Explaination:
Sites different from active site of enzyme ‘ where a molecule can bind and affect the active site is called allosteric site. Some drugs may also bind at this site.

---

52. Where are receptors located?

Answer/Explanation

Answer:
Explaination:
Receptors are embedded in cell membrane.

---

53. What is the harmful effect of hyperacidity?

Answer/Explanation

Answer:
Explaination:
It causes pain and may lead to formation of ulcer in stomach.

---

54. Write the name of an antacid which is often used as a medicine.

Answer/Explanation

Answer:
Explaination:
Ranitidine or NaHCO₃ or a mixture of Al(OH)₃ and Mg(OH)₂ is used as antacid.

---

55. Give an example of antihistamine.

Answer/Explanation

Answer:
Explaination:
Brompheniramine (Dimetapp).

---

56. Which class of drugs is used in sleeping pills? [Delhi 2013]

Answer/Explanation

Answer:
Explaination:
Tranquilizers, (hypnotics)

---

57. Define the following and give one example: Tranquilizers [Delhi 2017,12]

Answer/Explanation

Answer:
Explaination:
Tranquilizers: Those drugs which reduce anxiety and produce a feeling of well being, e.g., Equanil, seconal, etc.

---

58. What is the cause of a feeling of depression in human beings? Name a drug which can be useful in treating this depression. [AI2012]

Answer/Explanation

Answer:
Explaination:
If the level of noradrenaline is low, then signal sending activity is low. It leads to depression. These drugs inhibit enzymes which catalyse
the degradation of noradrenaline which is neurotransmitter and thus, counteract the effect of depression. Chlordiazepoxide and meprobamate are mild tranquilizers suitable for relieving tension. Equanil is used in controlling depression and hypertension.

---

59. What are the uses of narcotic analgesics?

Answer/Explanation

Answer:
Explaination:
These drugs are mainly used for the relief of cardiac pain, pains of terminal cancer, child birth, etc.

---

60. Which type of drugs come under antimicrobial drugs?

Answer/Explanation

Answer:
Explaination:
Antiseptics, antibiotics and disinfectants are antimicrobial drugs.

---

61. What is the commonality between the antibioitic arsphenamine and azodye?

Answer/Explanation

Answer:
Explaination:
Arsphenamine possesses —As=As— linkage that resembles —N=N— linkages in azodye.

---

62. What is meant by a ‘broad spectrum antibiotic’? [Delhi 2019,17,14(C)]

Answer/Explanation

Answer:
Explaination:
Those antibiotics which are effective for large number of microorganisms are called ‘broad spectrum antibiotics’, e.g. chloramphenicol, tetracycline, etc.

---

63. What is meant by ‘narrow spectrum antibiotics’? Give one example. [Delhi 2017,13(C); Foreign 2012]

Answer/Explanation

Answer:
Explaination:
Those antibiotics which are effective against only particular micro-organism are called narrow spectrum antibiotics, e.g. Ampicillin, Streptomycin, etc.

---

64. Describe the following types of substances, giving suitable examples: Antiseptics [Chennai, Uttarakhand 2019; Delhi 2017]

Answer/Explanation

Answer:
Explaination:
Antiseptics: Those chemicals which prevent the growth of micro-organisms are called antiseptics, e.g. Dettol, 0.2% solution of phenol.

---

65. Give an example of disinfectant.

Answer/Explanation

Answer:
Explaination:
SO₂ in very low concentration, 0.1% phenol, KMnO₄

---

66. Give an example of antifertility drug.

Answer/Explanation

Answer:
Explaination: Novestrol.

---

67. State a reason of the following statement: The use of the sweetner aspartame is limited to cold foods and drinks. [All India 2014(C)]

Answer/Explanation

Answer:
Explaination: Because it is unstable at high temperature.

---

68. Name a food preservative which is most commonly used by food producers.

Answer/Explanation

Answer:
Explaination: Common salt is used as food preservative.

---

69. Give an example of antioxidant.

Answer/Explanation

Answer:
Explaination: Butylated hydroxy toluene (BHT).

---

70. Why soaps are biodegradable whereas detergents are non-biodegradable? [Delhi 2019]

Answer/Explanation

Answer:
Explaination:
Soaps are 100% biodegradable because it is decomposed by micro-organisms and does not create water pollution.

---

71. What is a soft soap?

Answer/Explanation

Answer:
Explaination:
Soft soaps are potassium salts of fatty acids.

---

72. Describe and illustrate with an example, a detergent.

Answer/Explanation

Answer:
Explaination:
Detergent is sodium or potassium salt of benzene sulphonic acid or sulphonate of unsaturated hydrocarbons of alkene type, e.g., sodium alkylbenzene sulphonate.

---

73. Which category of the synthetic detergents is used in toothpaste? [Delhi 2019]

Answer/Explanation

Answer:
Explaination: Anionic detergents.

---

74. Hair shampoos belong to which class of synthetic detergent?

Answer/Explanation

Answer:
Explaination: Cationic detergents.

---

75. Dishwashing soaps are synthetic detergents. What is their chemical nature?

Answer/Explanation

Answer:
Explaination: Non-ionic detergents.

---

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Free PDF Download of CBSE Chemistry Multiple Choice Questions for Class 12 with Answers Chapter 15 Polymers. Chemistry MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Polymers MCQs Pdf with Answers to know their preparation level.

Polymers Class 12 Chemistry MCQs Pdf

1. The monomer of polystyrene is
(a) C₂H —CH=CH₂
(b) CH₂=CHCl
(c) C₆H₅CH=CH₂
(d) CH₂=CH—CHO

Answer/Explanation

Answer: c
Explaination:
(c) C₆H₅—CH=CH₂ is monomer of polystyrene.

---

2.

Answer/Explanation

Answer: a
Explaination:

---

3.
(a) addition polymer
(b) thermosetting polymer
(c) homopolymer
(d) condensation copolymer (Nylon-66)

Answer/Explanation

Answer: d
Explaination:
(d) It is condensation copolymer of Hexamethylene diamine (H2N(CH2)6NH2) and adipic acid,

---

4. Which of the following statements is not true?
(a) Natural rubber is frans-polyisoprene
(b) Buna-S is addition copolymer of butadiene and styrene
(c) Natural rubber is cis 1, 4-polymer of isoprene
(d) Vulcanisation makes rubber hard due to cross linkages with sulphur.

Answer/Explanation

Answer: a
Explaination:
(a) Natural rubber is cis- polyisoprene

---

5. Which of the following is not correct?

Answer/Explanation

Answer: a
Explaination:

is polymer of 2-chloro-1,3-butadiene (Chloroprene)

---

6. Which of the following has ester linkages?
(a) Nylon
(b) Bakelite
(c) Terylene
(d) PVC

Answer/Explanation

Answer: c
Explaination:
(c) Terylene is polyester, it has many ester linkages.

---

7. Which of the following is thermosetting polymer
(a) Neoprene
(b) PVC
(c) Nylon-6,6
(d) Bakelite

Answer/Explanation

Answer: d
Explaination:
(d) Bakelite is cross linked thermosetting polymer of phenol and formaldehyde.

---

8. Caprolactum is used for preparation of
(a) Nylon-6
(b) Nylon-6,6
(c) Nylon 6, 10
(d) Nylon-2 – Nylon-6

Answer/Explanation

Answer: a
Explaination:
(a) Nylon-6 is polymer of caprolactum.

---

9. The polymer used in orthopaedic devices and in controlled drug release is
(a) Orion
(b) PTFE
(c) SBR
(d) PHBV

Answer/Explanation

Answer: a
Explaination:
(a) PHBV is biocompatible, used in orthopaedic devices and controlled drug release. Orion is

SBR is styrene butadiene rubber.

---

10. Which of the following is not correct regarding terylene?
(a) Step growth polymer
(b) Synthetic fibre
(c) also called dacron
(d) Thermosetting plastic

Answer/Explanation

Answer: d
Explaination:
(d) It is synthetic fibre condensation, step growth polymer also called dacron.

---

11. The polymer which is used in manufacture of squeeze bottles is
(a) Polystyrene
(b) Teflon
(c) Polypropene
(d) Low density polythene

Answer/Explanation

Answer: d
Explaination:
(d) LDP is used for making squeeze bottles, flexible hose pipe.

---

12. The polymer containing strong intermolecular H-bonding and crystalline nature is
(a) Polystyrene
(b) Natural rubber
(c) Teflon
(d) Nylon 6, 6

Answer/Explanation

Answer: d
Explaination:
(d) Nylon 6, 6 is fibre with strong intermolecular H-bonding and is crystalline in nature.

---

13. Which of the following is initiator in free radical polymerisation?
(a) Benzoyl peroxide
(b) AlCl₃
(c) HNO₃
(d) Bu-Li

Answer/Explanation

Answer: a
Explaination:
(a) Benzoyl peroxide undergoes homolytic fission to form free radicals and acts as initiator.

---

14. Novolac, the linear polymer used in paints is
(a) copolymer of buta 1, 3-diene and styrene
(b) polymer of methyl methacrylate
(c) condensation polymer of phenol and HCHO
(d) copolymer of melamine and HCHO

Answer/Explanation

Answer: c
Explaination:
(c) It is copolymer of phenol and HCHO, linear.

---

15. Which of the following is not a semisynthetic polymer? [NCERT Exemplar]
(a) cw-polyisoprene .
(b) Cellulose nitrate
(c) Cellulose acetate
(d) Vulcanised rubber

Answer/Explanation

Answer: a
Explaination:
(a) cis-polyisoprene is natural rubber, others are semisynthetic because these are obtained from natural polymers by suitable process.

---

16. The commercial name of polyacrylonitrile is __________ . [NCERT Exemplar]
(a) Dacron
(b) Orion (acrilan)
(c) PVC
(d) Bakelite

Answer/Explanation

Answer: b
Explaination:

artificial wool, used for making carpets etc.

---

17. Zeigler – Natta catalyst is used in making
(a) LDPE
(b) HDPE
(c) Polystyrene
(d) PMMA

Answer

Answer: b

---

18. Natural rubber in a polymer of
(a) Butadiene
(b) Ethyne
(c) Styrene
(d) Isoprene

Answer

Answer: d

---

19. Which of the following is a biodegrable polymer?
(a) Cellulose
(b) Polyethene
(c) PVC
(d) Nylon-6

Answer

Answer: a

---

20. A polymer of butadiene and acrylonitrile is called
(a) Buna-2
(b) Buna-N
(c) Buna-S
(d) Buna-A

Answer

Answer: b

---

21. The manufacture of nylon-6 involves condensation of
(a) Phenol and formaldehyde
(b) Urea and formaldehyde
(c) Adipic acid and hexamethylene diamine
(d) Ethylene glycol and pthalic acid

Answer

Answer: c

---

22. Match List-I and List-II and select the correct answer using the codes below the lists:

Answer

Answer: d

---

23. F₂C = CF₂ is a monomer of
(a) Teflon
(b) Glyptal
(c) Nylon-6
(d) Buna-S

Answer

Answer: a

---

24. Which of the following is used in tyre cords?
(a) Terylene
(b) Polyethylene
(c) Polypropylene
(d) Nylon-6

Answer

Answer: d

---

25. PHBV has _______ type of linkages
(a) Amide
(b) Ester
(c) Diene
(d) Nitrile

Answer

Answer: b

---

26. The vulcanised rubber has
(a) High water absorption, resistant to oxidation and good elasticity
(b) High water absorption, susceptible to oxidation and no elasticity
(c) High water absorption, susceptible to oxidation and good elasticity
(d) Low water absorption, resistance to oxidation and good elasticity.

Answer

Answer: d

---

27. Which of the following polymer is biodegradable? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(c) is PHBV, biodegradable,
(a) is Neoprene
(b) Buna-N
(d) Nylon-6, 6.

---

28. In which of the following polymers ethylene glycol is one of the monomer units? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a) has HOCH2—CH2—OH as one of the monomers of terylene
(b) Polythene
(c) Buna-S
(d) PHBV

---

29. Which of the following statements is not true about low density polythene? [NCERT Exemplar]
(a) Tough
(b) Hard
(c) Poor conductor of electricity
(d) Highly branched structure

Answer/Explanation

Answer: b
Explaination:
(b) It is not hard but flexible, branched, tough, poor conductor of electricity.

---

Note: In the following questions two or more options may be correct. (Q.20 to Q.22)
30. Which of the following polymers, need atleast one diene monomer for their preparation? [NCERT Exemplar]
(a) Dacron
(b) Buna-S
(c) Neoprene
(d) Novolac

Answer/Explanation

Answer:
Explaination:
(b) and (c). Buna-S needs buta 1, 3-diene and Neoprene needs 2-chloro 1,3-butadiene. Dacron and Novolac are condensation polymers.

---

31. Which of the folloiwng are characteristics of thermosetting polymers? [NCERT Exemplar]
(a) Heavily branched cross linked polymers,
(b) Linear slightly branched long chain molecules.
(c) Become infusible on moulding so cannot be reused.
(d) Soften on heating and harden on cooling, can be reused.

Answer/Explanation

Answer:
Explaination:
(a) and (c) e.g. Bakelite is used for making electrical switches and switch boards.

---

32. Which of the following polymers are thermoplastic? [NCERT Exemplar]
(a) Teflon
(b) Natural rubber
(c) Neoprene
(d) Polystyrene

Answer/Explanation

Answer:
Explaination:
(a) and (d), Teflon is used in non-stick kichen ware, polystyrene is used to make toys and radio and T.V. cabinets.

---

33. Match the polymer of column I with correct monomer of column II. [NCERT Exemplar]

Column I	Column II
(a) High density polythene	(i) Isoprene
(b) Neoprene	(ii) Tetrafluoro- ethene
(c) Natural rubber	(iii) Chloroprene
(d) Teflon	(iv) Acrylonitrile
(e) Acrilan	(v) Ethene

Answer/Explanation

Answer:
Explaination:
(a) (v)
(b) (in)
(c) (i)
(d) (ii)
(e) (iv)

---

34. Match the polymers given in Column I with their chemical names given in Column II. [NCERT Exemplar]

Column I	Column II
(a) Nylon 6	(i) Polyvinyl chloride
(b) PVC	(ii) Polyacrylonitrile
(c) Acrilan	(iii) Polycaprolactum
(d) Natural rubber	(iv) Low density polythene
(e) LDP	(v) cis-polyisoprene

Answer/Explanation

Answer:
Explaination:
(a) (iii)
(b) (i)
(c) (ii)
(d) (v)
(e) (iv)

---

35. Match the polymers given in Column I with their commercial names given in Column II. [NCERT Exemplar]

Column I	Column II
(a) Polyester of glycol and phthalic acid	(i) Novolac
(b) Copolymer of 1, 3-butadiene and styrene	(ii) Glyptal
(c) Phenol and formaldehyde resin	(iii) Buna-S
(d) Polyester of glycol and terephthalic acid	(iv) Buna-N
(e) Copolymer of 1, 3-butadiene and acrylonitrile	(v) Dacron

Answer/Explanation

Answer:
Explaination:
(a) (ii)
(b) (iii)
(c) (i)
(d) (v)
(e) (iv)

---

36. Match the polymers given in Column I with their main applications given in Column II. [NCERT Exemplar]

Column I	Column II
(a) Bakelite	(i) Unbreakable crockery
(b) Low density polythene	(ii) Non-stick cook-wares
(c) Melamine- formaldehyde  resin	(iii) Packaging material for shock absorbance
(d) Nylon 6	(iv) Electrical switches
(e) Polytetrafluo- roethane	(v) Squeeze bottles
(f) Polystyrene	(v) Tyre, cords

Answer/Explanation

Answer:
Explaination:
(a) (iv)
(b) (v)
(c) (i)
(d)(vi)
(e) (ii)
(f) (iii)

---

37. Match the polymers given in Column I with the preferred mode of polymerisation followed by their monomers. [NCERT Exemplar]

Column I	Column II
(a) Nylon-6,6	(i) Free radical Polymeriaation
(b) PVC	(ii) Ziegler-Natta polymerisation or coordination polymerisation
(c) HDP	(iii) Anionic polymerisation
	(iv) Condensation polymerisation

Answer/Explanation

Answer:
Explaination:
(a) (iv)
(b) (i)
(c) (ii)

---

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (Q.28 to Q.30)
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct but reason is wrong statement.
(d) Assertion is wrong but reason is correct statement.
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.
38. Assertion: Rayon is a semi synthetic polymer and is taken as a better choice than cotton fabric. [NCERT Exemplar]
Reason: Mechanical and aesthetic properties of cellulose can be improved by acetylation.

Answer/Explanation

Answer: a
Explaination:
(a) Assertion and reason both are correct and reason is correct explanation of assertion.

---

39. Assertion: Most of the Synthetic polymers are not biodegradable. [NCERT Exemplar]
Reason: Polymerisation process induces toxic character in organic molecules.

Answer/Explanation

Answer: c
Explaination:
(c) Assertion is correct but reason is wrong statement.

---

40. Assertion: Olefinic monomers undergo addition polymerisation. [NCERT Exemplar]
Reason: Polymerisation of vinyl chloride is initiated by peroxides/ persulphates.

Answer/Explanation

Answer: e
Explaination:
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.

---

41. Trans-polyisoprene, a rubber like material is called __________ .

Answer/Explanation

Answer:
Explaination: Gutta percha

---

42. High density polythene __________ polymer of ethene.

Answer/Explanation

Answer:
Explaination: linear

---

43. A copolymer can be addition or condensation. [True/False]

Answer/Explanation

Answer:
Explaination:
True, e.g. Nylon-66 (condensation copolymer), Buna-S (addition copolymer).

---

44.

is Nylon 6, 10, synthetic fibre. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

45.

is Melamine-formaldehyde resin, a thermosetting polymer. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

46. Which of the following is natural polymer? Buna-S, Protein, PVC [Chennai 2019; AI2014]

Answer/Explanation

Answer:
Explaination:
Protein is a natural polymer.

---

47. Give an example of semi-synthetic polymer.

Answer/Explanation

Answer:
Explaination:
Cellulose nitrate.

---

48. What are synthetic polymers?

Answer/Explanation

Answer:
Explaination:
These are man-made polymers extensively used in daily life as well as in industry, e.g. plastic (polythene)

---

49. Give an example of linear and branched chain polymer each.

Answer/Explanation

Answer:
Explaination:
Linear polymer – Polyvinyl chloride
Branched chain polymer – Low density polythene.

---

50. Identify the type of polymer given in the following figure. [HOTS]

Answer/Explanation

Answer:
Explaination: Cross-linked polymer

---

51. Identify the type of polymer:
—A—A—A—A—A—A—

Answer/Explanation

Answer:
Explaination: Homopolymer

---

52.

a homopolymer or a copolymer? [AI 2013]

Answer/Explanation

Answer:
Explaination: It is homopolymer.

---

53.

a homopolymer or a copolymer? [AI 2013; NCERT]

Answer/Explanation

Answer:
Explaination: It is homopolymer.

---

54. Define the term, ‘homopolymerisation’ giving an example. [Delhi 2013(C); 2012]

Answer/Explanation

Answer:
Explaination:
The process in which only one type of monomer undergoes polymerisation is called homopolymerisation, e.g. formation of polythene from ethene is homopolymerisation.

---

55. How does a homopolymer differ from a copolymer? [AI 2014(C)]

Answer/Explanation

Answer:
Explaination:
Homopolymer is formed by the same monomer unit, whereas copolymer is formed by repeating two different monomers.

---

56. Identify the type of polymer:
—A—B—B—A—A—A—B—A—

Answer/Explanation

Answer:
Explaination: Copolymer

---

57. What is the repeating structural unit in polythene polymer? [AI 2011]

Answer/Explanation

Answer:
Explaination: (— CH₂—CH₂—)_n

---

58. Draw the structure of the monomer for the following polymer: Polypropene [Delhi 2012]

Answer/Explanation

Answer:
Explaination:

---

59. What is the primary structure feature necessary for a molecule to make it useful in a condensation polymerisation reactioris?

Answer/Explanation

Answer:
Explaination:
Monomers should have more than one functional group (bifunctional).

---

60. Give one example of a condensation polymer? [AI 2013]

Answer/Explanation

Answer:
Explaination: Nylon 6, 6.

---

61. Give an example of elastomers.

Answer/Explanation

Answer:
Explaination:
Natural rubber, Buna-S, Buna-N, Neoprene is an elastomer.

---

62. Based on molecular forces, what type of polymer is neoprene? [AI 2014]

Answer/Explanation

Answer:
Explaination: Elastomer.

---

63. Which of the following is a fibre?
Nylon, Neoprene, PVC [AI 2014]

Answer/Explanation

Answer:
Explaination: Nylon is fibre.

---

64. Which factor imparts crystalline nature to a polymer like nylon?

Answer/Explanation

Answer:
Explaination:
It is strong intermolecular forces of attraction like hydrogen bonding which leads to close packing of chains that impart crystalline nature.

---

65. Which of the following is a thermoplastic polymer?
Bakelite, Polystyrene, Urea-formaldehyde resin.

Answer/Explanation

Answer:
Explaination: Polystyrene.

---

66. Give an example of thermosetting polymer.

Answer/Explanation

Answer:
Explaination: Bakelite.

---

67. Out of chain growth polymerisation and step growth polymerisation, in which type will you place the following.
(—A—)_m + (—A—)_n → (A—)_m (—A—)_n or —(A—A—)_m+n

Answer/Explanation

Answer:
Explaination: Chain growth polymer

---

68. Write the names of monomers of the following polymer: [AI 2016]

Answer/Explanation

Answer:
Explaination:

---

69. What does the part ‘6, 6’ mean in the name nylon-6, 6? [Chennai 2019]

Answer/Explanation

Answer:
Explaination:
It means each monomer of nylon has six carbon atoms. Adipic acid (HOOC—(CH₂)₄—COOH) and hexamethylenediamine (H₂N—(CH₂)₆—NH₂).

---

70. What is natural rubber?

Answer/Explanation

Answer:
Explaination:
It may be considered as a linear polymer of cis-isoprene (2-methyl-1,3-butadiene) and is also known as cis-1,4-polyisoprene.

---

71. Give the chemical reaction involved in the formation of Neoprene from chloroprene.

Answer/Explanation

Answer:
Explaination:

---

72. Why is the molecular mass of polymer is always expressed as an average?

Answer/Explanation

Answer:
Explaination:
The polymer sample contains chains of varying lengths, therefore, its molecular mass is always expressed as an average.

---

73. Give an example of biodegradable polymer.

Answer/Explanation

Answer:
Explaination:
Poly P-hydroxybutyrate-co-P-hydroxy valerate (PHBV)

---

74. Give two uses of polystyrene.

Answer/Explanation

Answer:
Explaination:
It is used as insulator and in manufacture of toys and television cabinets.

---

75. Can enzyme be called a polymer?

Answer/Explanation

Answer:
Explaination:
Yes. Enzymes are biocatalysts which are proteins, the polymers of amino acids.

---

We hope the given Chemistry MCQs for Class 12 with Answers Chapter 15 Polymers will help you. If you have any query regarding CBSE Class 12 Chemistry Polymers MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Chemistry Multiple Choice Questions for Class 12 with Answers Chapter 14 Biomolecules. Chemistry MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Biomolecules MCQs Pdf with Answers to know their preparation level.

Biomolecules Class 12 Chemistry MCQs Pdf

1. RNA and DNA are chiral molecules, their chirality is due to
(a) chiral bases
(b) chiral phosphate units
(c) D-sugar component
(d) L-sugar component

Answer/Explanation

Answer: c
Explaination:
(c) D-sugar component.

---

2. Glucose does not react with
(a) NH₂OH
(b) Cone. HNO₃
(c) (CH₃CO)₂O
(d) NaHSO₃

Answer/Explanation

Answer: d
Explaination:
(d) NaHSO₃ does not react with glucose.

---

3. The glycosidic linkage involved in linking the glucose units in amylose part of starch is
(a) C₁ -C₄ β-linkage
(b) C₁ -C₆ α-linkage
(c) C₁ -C₄ α-linkage
(d) C₁ -C₆ β-linkage

Answer/Explanation

Answer: c
Explaination:
(c) C₁-C₄ α-linkage are involved in α-glucose, in amylose, linear polymer or a-glucose in starch.

---

4. A basic amino acid among the following is
(a) glycine
(b) valine
(c) histidine
(d) leucine

Answer/Explanation

Answer: c
Explaination:
(c) It has two amino groups and one —COOH group.

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5. Glucose on oxidation with Br₂(aq) gives
(a) Gluconic acid
(b) Tartaric acid
(c) Sachharic acid
(d) Meso-oxalic acid

Answer/Explanation

Answer: a
Explaination:
(a) Br₂/H₂O oxidises —CHO to —COOH.

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6. Which of the following is non-reducing sugar?
(a) Glucose
(b) Sucrose
(c) Maltose
(d) Lactose

Answer/Explanation

Answer: b
Explaination:
(b) Sucrose.

---

7. Which of the following statements is not correct?
(a) Ovalbumin is a simple food reserve in egg white.
(b) Blood proteins thrombin and fibrinogen are involved in blood clotting.
(c) Denaturation makes the proteins more active.
(d) Insulin maintains sugar level in the blood of a human body.

Answer/Explanation

Answer: c
Explaination:
(c) Denaturation leads to biological activity.

---

8. Deficiency of vitamin B, causes the disease
(a) convulsions
(b) beri beri
(c) cheilosis
(d) sterility

Answer/Explanation

Answer: b
Explaination:
(b) It is caused by deficiency of water soluble B₁.

---

9. Which one of the following metals is required as cofactor by all enzymes utilizing ATP in phosphate transfer?
(a) K
(b) Ca
(c) He
(d) Mg

Answer/Explanation

Answer: d
Explaination:
(d) Mg acts as cofactor.

---

10. In aqueous solution, an amino acid exist as
(a) cation
(b) anion
(c) zwitter ion
(d) neutral molecule

Answer/Explanation

Answer: c
Explaination:

---

11. Glycogen is a branched chain polymer of α-D-glucose units in which chain is formed by C₁—C₄ glycosidic linkage whereas branching occurs by the formation of C₁– C₆ glycosidic linkage. Structure of glycogen is similar to __________ . [NCERT Exemplar]
(a) Amylose
(b) Amylopectin
(c) Cellulose
(d) Glucose

Answer/Explanation

Answer: b
Explaination:
(b) Glycogen is branched chain polymer of α-glucose like amylopectin.

---

12. Which of the following polymer is stored in the liver of animals? [NCERT Exemplar]
(a) Amylose
(b) Cellulose
(c) Amylopectin
(d) Glycogen

Answer/Explanation

Answer: d
Explaination:
(d) Glycogen is stored in liver of animals.

---

13. Which of the following pairs represents anomers? [NCERT Exemplar]

Answer/Explanation

Answer: c
Explaination:
(c) They differ in position of —OH group on C—1 carbon.

---

14. Proteins are found to have two different types of secondary structures viz. α-helix and β-pIeated sheet structure, α-helix structure of protein is stabilised by : [NCERT Exemplar]
(a) Peptide bonds
(b) van der Waals forces
(c) Hydrogen bonds
(d) Dipole-dipole interactions

Answer/Explanation

Answer: c
Explaination:
(c) H-bonds are present in α-helix.

---

15. Which of the following acids is a vitamin? [NCERT Exemplar]
(a) Aspartic acid
(b) Ascorbic acid
(c) Adipic acid
(d) Saccharic acid

Answer/Explanation

Answer: b
Explaination:
(b) Ascorbic acid is vitamin C, antioxidant, water soluble and its deficiency causes scurvy.

---

16. Dinucleotide is obtained by joining two nucleotides together by phosphodiester linkage. Between which carbon atoms of pentose sugars of nucleotides are these linkages present? [NCERT Exemplar]
(a) 5’and 3′
(b)1’and 5′
(c) 5′ and 5′
(d) 3′ and 3′

Answer/Explanation

Answer: a
Explaination:
(a) 5′ and 3′ carbon atoms.

---

17. Nucleic acids are the polymers of __________ . [NCERT Exemplar]
(a) Nucleosides
(6) Nucleotides
(c) Bases
(d) Sugars

Answer/Explanation

Answer: b
Explaination:
(b) Nucleic acids are polymers of nucleotides.

---

18. Each polypeptide in a protein has aminoacids linked with each other in a specific sequence. This sequence of amino acids is said to be __________ . [NCERT Exemplar]
(а) primary structure of proteins.
(b) secondary structure of proteins.
(c) tertiary structure of proteins.
(d) quaternary structure of proteins.

Answer/Explanation

Answer: a
Explaination:
(a) It is called primary structure having

peptide bonds.

---

19. Which of the following B group vitamins can be stored in our body? [NCERT Exemplar]
(a) Vitamin B₁
(b) Vitamin B₂
(c) Vitamin B₆
(d) Vitamin B₁₂

Answer/Explanation

Answer: d
Explaination:
(d) Vitamin B₁₂ is stored in our body as it is neither water soluble nor fat soluble.

---

20. Which of the following reactions of glucose can be explained only by its cyclic structure? [NCERT Exemplar]
(a) Glucose forms pentaacetate.
(b) Glucose reacts with hydroxylamine to form an oxime.
(c) Pentaacetate of glucose does not react with hydroxylamine.
(d) Glucose is oxidised by nitric acid to gluconic acid.

Answer/Explanation

Answer: c
Explaination:
(c) It means glucose pentaacetate has cyclic structure which does not have free aldehyde group.

---

21. The sugar present in milk is
(a) Sucrose
(b) Maltose
(c) Glucose
(d) lactose

Answer

Answer: d

---

22. α-D (+) glucose and β-D (+) – glucose are
(a) Enantiomers
(b) Geometrical isomers
(c) Anomers
(d) Epimers

Answer

Answer: c

---

23. Distinction between glucose and fructose can be done by
(a) Benedict’s solution
(b) Tollen’s reagent
(c) Selivanoff’s reagent
(d) Fehling solution

Answer

Answer: c

---

24. Which does not show mutarotation?
(a) Glucose
(b) Maltose
(c) Fructose
(d) Sucrose

Answer

Answer: d

---

25. The reagent used for obtaining osazone derivative of fructose is
(a) NH₂OH
(b) NH₂ – NH₂
(c) NH₂ – NHC₆H₅
(d) 2, 4-DNP

Answer

Answer: c

---

26. Amylopectin is a polymer of
(a) β-D-glucose
(b) α-D-glucose
(c) β-D-frutose
(d) α-D-fructose

Answer

Answer: b

---

27. Hydrolysis of sucrose gives
(a) Glucose only
(b) Glucose + fructo
(c) Glucose and galactose
(d) Maltose

Answer

Answer: b

---

28. The disease resulting from the intake of amino acid deficient diet is
(a) Kwasiorkar
(b) Pernicicres anaemia
(c) PEM
(d) Haemophilio

Answer

Answer: a

---

29. Kerating present in hair is an example of
(a) Fibrous protein
(b) Globular protein
(c) Conjugated protein
(d) Derived protein

Answer

Answer: a

---

30. DNA and RNA differ in
(a) Sugar
(b) Purines
(c) Pyrimidines
(d) Both (a) and (c)

Answer

Answer: d

---

31. The vitamin present in oils and fats are
(a) A and D
(b) B and C
(c) A and B
(d) A and C

Answer

Answer: a

---

Note: In the following questions two or more options may be correct. (Q.21 to Q.23)
32. Carbohydrates are classified on the basis of their behaviour on hydrolysis and also as reducing or non-reducing sugar. Sucrose is a __________ . [NCERT Exemplar]
(a) monosaccharide
(b) disaccharide
(c) reducing sugar
(d) non-reducing sugar

Answer/Explanation

Answer:
Explaination:
(b) and (d). It is disachharide made up of glucose and fructose and does not have free aldehyde group, therefore, non-reducing sugar.

---

33. Amino acids are classified as acidic, basic or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Which of the following are acidic? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(b) and (d) are acidic amino acids.
∵ they have 2—COOH groups and one —NH₂ group.

---

34.

(a) α-Amino acid
(b) Basic amino acid
(c) Amino acid synthesised in body
(d) β-Amino acid

Answer/Explanation

Answer:
Explaination:
(a) and (b). It is a-amino acid.
∵ —NH₂ and—COOH groups are attached to same carbon. It is basic because it has 2 amino groups and one —COOH group.

---

35. Match the vitamins given in Column I with the deficiency disease they cause given in Column II. [NCERT Exemplar]

Column I (Vitamins)	Column II (Diseases)
(a) Vitamin A	(i) Pernicious anaemia
(b) Vitamin B1	(ii) Increased blood clotting time
(c) Vitamin B12	(iii) Xerophthalmia
(d) Vitamin C	(iv) Rickets
(e) Vitamin D	(v) Muscular weakness
(i) Vitamin E	(vi) Night blindness
(g) Vitamin K	(vii) Beri Beri
	(viii) Bleeding gums
	(ix) Osteomalacia

Answer/Explanation

Answer:
Explaination:
(a) (iii) and (vi)
(b) (vii)
(c) (i)
(d) (viii)
(e) (iv) and (i)
(f) (v)
(g) (ii)

---

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (Q.25 to Q.26)
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct but reason is wrong statement.
(d) Assertion is wrong but reason is correct statement.
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.
36. Assertion: D (+) – Glucose is dextrorotatory in nature.
Reason: ‘D’ represents its dextrorotatory nature. [NCERT Exemplar]

Answer/Explanation

Answer: c
Explaination:
(c) Assertion is correct but reason is wrong statement. ‘D’ represents configuration, i.e., – OH group on right side on first chiral carbon from the bottom (+) dextrorotatory, it is also denoted by d(+).

---

37. Assertion: Vitamin D can be stored in our body.
Reason: Vitamin D is fat soluble vitamin. [NCERT Exemplar]

Answer/Explanation

Answer: a
Explaination:
(a) Assertion and reason both are correct and reason is correct explanation of assertion.

---

38. Guanine and adenine belong to __________ and Thymine and Uracil are __________ bases.

Answer/Explanation

Answer:
Explaination: purines, pyrimidines

---

39. Enzymes are __________ proteins.

Answer/Explanation

Answer:
Explaination: globular

---

40. Cellulose is linear polymer of __________.

Answer/Explanation

Answer:
Explaination: β-glucose.

---

41. Invert sugar is mixture of glucose and fructose and is leavorotatory. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

42. Amylose is linear water soluble, amylopectin is water insoluble, branch chain polymer of a-glucose are two components of starch. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

43. During denaturation of proteins, tertiary and secondary structure are ruptured but primary structure remains the same. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

44. What are monosaccharides?

Answer/Explanation

Answer:
Explaination:
Monosaccharides are simple sugars which cannot be hydrolysed, e.g. glucose, fructose, galactose, ribose, deoxyribose, etc. are the examples of monosaccharides.

---

45. Name the linkage connecting monosaccha-ride units in polysaccharides.

Answer/Explanation

Answer:
Explaination: Glycosidic linkage.

---

46. What is the structural feature characterising reducing sugar?

Answer/Explanation

Answer:
Explaination:

---

47. Give an example each of the following: [DoE]
(i) Reducing sugar
(ii) Non-reducing sugar

Answer/Explanation

Answer:
Explaination:
(i) Glucose
(ii) Sucrose

---

48. Under what conditions glucose is converted to gluconic acid and saccharic acid?

Answer/Explanation

Answer:
Explaination:
Bromine water converts glucose to gluconic acid, whereas cone. HNO₃ converts to saccharic acid.

---

49. The letters ‘D’ or ‘L’ before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer. This refers to their relation with one of the isomers of glyceraldehyde. Predict whether the following compound has ‘D’ or ‘L’ configuration.

Answer/Explanation

Answer:
Explaination:
L-configuration because —OH group is on left side on first chiral ‘C’ from bottom.

---

50. Why does compound (A) given below not form an oxime?

Answer/Explanation

Answer:
Explaination:
It is because it does not have free aldehyde group, therefore, it does not form oxime with hydroxyl amine (NH₂OH).

---

51. Monosaccharides contain carbonyl group hence are classified as aldose or ketose. The number of carbon atoms present in the monosaccharide molecule are also considered for classification. In which class of monosaccharide will you place fructose ?

Answer/Explanation

Answer:
Explaination:
Fructose is keto hexose because it has 6 carbon atoms and ketone group.

---

52. Sucrose is dextrorotatory but the mixture obtained after hydrolysis is laevorotatory. Explain.

Answer/Explanation

Answer:
Explaination:
On hydrolysis, sucrose (dextrorotatory) gives » glucose (dextrorotatory +52.5) and fructose (laevorotatory, -92.4°). Since laevorotation of fructose is more than dextro-rotation of glucose, therefore, mixture is laevorotatory.

---

53. What are the products of hydrolysis of maltose? [AI 2014]

Answer/Explanation

Answer:
Explaination: 2 moles of Glucose.

---

54. Which disaccharide is found in milk?

Answer/Explanation

Answer:
Explaination: Lactose. It is more commonly known as milk sugar.

---

55. Which monosaccharide units are present in starch, cellulose and glycogen and which linkages link these units?

Answer/Explanation

Answer:
Explaination:
Starch is branched chain polymer of α-glucose, whereas cellulose is linear polymer of β-glucose. Glycogen is branched chain polymer of α-glucose.
In starch and glycogen, aα-glycosidic-linkage is present, whereas in cellulose β-glycosidic- linkage is present.

---

56. Which of the two components of starch is water soluble? [Delhi 2014; DoE]

Answer/Explanation

Answer:
Explaination:
Amylose is water soluble component in starch.

---

57. Which component of starch is a branched polymer of D-glucose and insoluble in water? [CBSE Sample Paper 2018; Delhi 2014]

Answer/Explanation

Answer:
Explaination:
Amylopectin.

---

58. Name the two components of D-glucose which constitute starch. [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
Amylose and amylopectin are two components of starch.

---

59. Why is cellulose not digested in human body?

Answer/Explanation

Answer:
Explaination:
Cellulose is not digested in human body because we do not have enzymes which can metabolise cellulose.

---

60. Name animal starch. Why is it called so?

Answer/Explanation

Answer:
Explaination:
Glycogen. Since its structure is similar to amylopectin and is rather more highly branched so it is also known as animal starch. It is present in liver, muscles and brain.

---

61. Why do amino acids show amphoteric behaviour? [Uttarakhand 2019]

Answer/Explanation

Answer:
Explaination:
They are basic (-NH₂) as well as acidic (-COOH), therefore, amphoteric in nature.

---

62. Out of a, p and y amino acids, which ‘ amino acids are obtained by hydrolysis of proteins? Give its general structure.

Answer/Explanation

Answer:
Explaination:
Only a-amino acids are obtained by hydrolysis of proteins. Its general structure

---

63. Give any two examples of essential amino acids.

Answer/Explanation

Answer:
Explaination: Valine and Leucine.

---

64. Write the name of linkage joining two amino acids. [AI 2013]

Answer/Explanation

Answer:
Explaination: Peptide linkage

---

65. Give an example for each of the fibrous protein and globular protein. [AI 2016]

Answer/Explanation

Answer:
Explaination:
Keratin is fibrous protein and albumin is globular protein.

---

66. What type of bonding occurs in P-pleated structure of proteins?

Answer/Explanation

Answer:
Explaination:
In p-pleated structure, the peptide chains are arranged side by side and these are held by a large number of intermolecular

---

67. What is meant by tertiary structure of proteins?

Answer/Explanation

Answer:
Explaination:
Tertiary structure of proteins involves further folding and twisting of secondary structure of proteins. It has compact and folded structure. It involves H-bonding, disulphide linkage, ionic or salt bridges and hydrophobic interactions. It has van der Waals’ and electrostatic forces of attraction.

---

68. What are the structural changes found during denaturation of proteins?

Answer/Explanation

Answer:
Explaination:
During denaturation of proteins, 2° and 3° structures are distroyed but 1° structure remains intact.

---

69. What are biocatalysts? Give an example. [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
Those catalysts which catalyse biochemical reactions are called biocatalysts, e.g. invertase catalyses hydrolysis of cane-sugar to form glucose and fructose.

---

70. Some enzymes are named after the reaction, where they are used. What name is given to the class of enzymes which catalyse the oxidation of one substrate with simultaneous reduction of another substrate.

Answer/Explanation

Answer:
Explaination:
Oxidoreductase.

---

71. How do enzymes help a substrate to be attacked by the reagent effectively?

Answer/Explanation

Answer:
Explaination:
Active site of enzyme holds the substrate molecule in suitable position so that it can be attacked by reagent effectively.

---

72. Out of the following groups, which group has all fat soluble vitamins:
(a) A, B-Complex, C, D
(b) A, D, E, K
(c) K, B-Complex, A, E
(d) C, A, E, D.

Answer/Explanation

Answer:
Explaination:
(b) A, D, E and K are the group of fat-soluble vitamin.

---

73. Name the deficiency diseases resulting from lack of vitamins A and E in the diet. [Delhi 2013(C); 2011(C); DoE]

Answer/Explanation

Answer:
Explaination:
(i) Night blindness is caused by lack of Vitamin A.
(ii) Loss of reproduction power is caused by deficiency of Vitamin E.

---

74. Which vitamin is linked with anti-sterility? [DoE]

Answer/Explanation

Answer:
Explaination: Vitamin E.

---

75. Aldopentoses named as ribose and 2-deoxyribose are found in nucleic acids. What is their relative configuration?

Answer/Explanation

Answer:
Explaination: D-configuration.

---

76. What are hormones? Give examples.

Answer/Explanation

Answer:
Explaination:
Hormones are chemical substances which are secreated by ductless endocrine glands and perform specific function e.g. Insulin metabolises glucose, testosterone in male, estradiol in female sex hormone.

---

77. What are non-steroid hormones? Name any one non-steroid hormone.

Answer/Explanation

Answer:
Explaination:
Non-steroid hormones do not contain steroid ring. An example of this type of hormone is insulin.

---

78. What is Thyroxine?

Answer/Explanation

Answer:
Explaination:
It is produced in thyroid gland, it is an iodine derivative of amino acid tyrosine.

---

79. What is cause of hypothyroidism? What are symptoms?

Answer/Explanation

Answer:
Explaination:
Low level of thyroxine is cause of hypothy-roidism, It is characterised by lethargyness and obesity. Nal should be added to common salt to prevent it.

---

80. What is hyperthyroidism?

Answer/Explanation

Answer:
Explaination:
Increased level of thyroxine leads to hyperthyroidism.

---

80. What is Addison’s disease?

Answer/Explanation

Answer:
Explaination:
If adrenal cortex does not function properly, it causes Addison’s disease, causing hypoglycemia (low level of glucose) weakness.

---

We hope the given Chemistry MCQs for Class 12 with Answers Chapter 14 Biomolecules will help you. If you have any query regarding CBSE Class 12 Chemistry Biomolecules MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Chemistry Multiple Choice Questions for Class 12 with Answers Chapter 13 Amines. Chemistry MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Amines MCQs Pdf with Answers to know their preparation level.

Amines Class 12 Chemistry MCQs Pdf

1.

Answer/Explanation

Answer: d
Explaination:

---

2. The major product of the reaction between /n-dinitro benzene with NH4HS is
(a) p-Dinitro benzene
(b) m-Diamino benzene
(c) m-nitroaniline
(d) p-Diamino benzene

Answer/Explanation

Answer: c
Explaination:

---

3.

Answer/Explanation

Answer: d
Explaination:

---

4. An organic compound C₇H₉N forms clear solution when dissolved in KOH after reacting with C₆H₅SO₂Cl, ‘A’ on diazotisation at 0°C and then reaction with β-naphthol gives orangish red dye. ‘A’ on electrophilic substitution gives single product. ‘A’ is
(a) 4-Methyl aniline
(b) 2-Methyl aniline
(c) 3-Methyl aniline
(d) N-Methyl aniline

Answer/Explanation

Answer: a
Explaination:

---

5.

(a) β-Alanine
(b) α-Alanine
(c) Ethylene diamine
(d) Oxamide

Answer/Explanation

Answer: a
Explaination:

---

6. The reaction of p-Toluidine with CHCl₃ and KOH gives.

Answer/Explanation

Answer: d
Explaination:
(d) It is carbylamine reaction, leads to formation of isocyanide (carbylamine).

---

7.

The compound ‘A’ is
(a) propane nitrile
(b) ethane nitrile
(c) nitro methane
(d) methyl isocyanate

Answer/Explanation

Answer: b
Explaination:

---

8.

The IUPAC name of ‘Y’ is
(a) N-isopropyl methanamine
(b) N-methyl propan-2-amine
(c) N-methyl propanamine
(d) butan-2-amine

Answer/Explanation

Answer: b
Explaination:

---

9.

Answer/Explanation

Answer: a
Explaination:
(a) sp > sp² > sp³. In CH₃C≡N, ‘N’ is sp hybridised, in pyridine sp² hybridised and (CH₃)₃N, it is sp³ hybridised.

---

10. The best reagent for converting 2-Phenyl propanamide into 2-phenyl propanamine is
(a) Br₂/NaOH
(b) excess of H₂
(c) I₂/P₄
(d) LiAlH₄ in ether

Answer/Explanation

Answer: d
Explaination:

---

11. Which one of the following can be prepared by Gabriel phthalimide synthesis?
(a) Aniline
(b) o-Toluidine
(c) Benzylamine
(d) N-Methyl ethanamine

Answer/Explanation

Answer: c
Explaination:

---

12.

Answer/Explanation

Answer: a
Explaination:

---

13. Diethyl amine, when treated with HN03 gives
(a) Diethyl ammonium nitrite
(b) Ethly alcohol
(c) N-nitroso diethyl amine
(d) Triethyl ammonium nitrite

Answer/Explanation

Answer: c
Explaination:

---

14. Choose the amide which on reduction with LiAlH₄ gives secondary amine.
(a) Ethanamide
(b) N-Methyl ethanamide
(c) N, N-diethyl ethanamide
(d) Benzamid

Answer/Explanation

Answer: b
Explaination:

---

15. 4-Nitrotoluene is treated with bromine to get P. ‘P’ is reduced with Sn/HCl to get compound ‘Q\ ‘Q’ is diazotised and the product is treated with phosphinic acid to get compound ‘R’. ‘R’ is oxidised with alkaline KMn04 to get ‘S’. Compound ‘S’ is
(a) 2-Bromo-4-hydroxy benzoic acid
(b) 2-Bromo benzoic acid
(c) 3-Bromo benzoic acid
(d) 4-Bromo benzoic acid

Answer/Explanation

Answer: b
Explaination:

---

16. In order to prepare a 1° amine from an alkyl halide with simultaneous addition of one CH₂ group in the carbon chain, the reagent used as source of nitrogen is ____________ . [NCERT Exemplar]
(a) Sodium amide, NaNH₂
(b) Sodium azide, NaN₃
(c) Potassium cyanide, KCN
(d) Potassium phthalimide, C₆H₄(CO)₂N^–K⁺

Answer/Explanation

Answer: c
Explaination:
(c) KCN is used to increase number of carbon atoms.

---

17. Amongst the given set of reactants, the most appropriate for preparing 2° amine is ____________ . [NCERT Exemplar]
(a) 2° R—Br + NH₃
(b) 2° R—Br + NaCN followed by H₂/Pt
(c) 1° R—NH2 + RCHO followed by H₂/Pt
(d) 1° R—Br (2 mol) + potassium phthalimide followed by H₃O⁺/heat

Answer/Explanation

Answer:
Explaination:

---

18. The order of basic strength of amines in aqueous solution is
(a) (CH₃)₃N > (CH₃)₂NH > CH₃NH₂ > NH₃
(b) CH₃NH₂ > (CH₃)₂ NH > (CH₃)₃N > NH₃
(c) NH₃ > (CH₃)₃N > (CH₃)₂NH > CH₃NH₂
(d) (CH₃)₂NH > CH₃NH₂ > (CH₃)₃N > NH₃

Answer/Explanation

Answer: d
Explaination:
(d) is correct 2° > 1° > 3° > NH3 because in 3° amines, there is stearic hindrance therefore, lone pair of electron is not readily available.

---

19. Which of the following is a 3° amine? [NCERT Exemplar]
(a) 1-methylcyclohexylamine
(b) Triethyl amine
(c) tert-butylamine
(d) N-methylaniline

Answer/Explanation

Answer: b
Explaination:
(b) Triethyl amine (C₂H₅)₃N is tertiary amine.

---

20. The correct IUPAC name for CH₂ = CHCH₂ NHCH₃ is [NCERT Exemplar]
(a) Allylmethylamine
(b) 2-amino-4-pentene
(c) 4-aminopent-l-ene
(d) N-methylprop-2-en-l-amine

Answer/Explanation

Answer: d
Explaination:
(d) Amino group is preferred over double bond.

---

21. Which of the following is the weakest Bronsted base? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a) Aniline is weakest because C₆H₅-group is electron withdrawing and there is +ve charge on 3 out of 5 resonating structures.

---

22. Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine? [NCERT Exemplar]
(a) H₂ (excess)/Pt
(b) LiAlH₄ in ether
(c) Fe and HCl
(d) Sn and HCl

Answer/Explanation

Answer: b
Explaination:
(b) LiAlH₄ is not good reducing agent to reduce nitro group.

---

23. The correct decreasing order of boiling points among amines and their corresponding acids and alcohols is
(a) R – CH₂ NH₂ > RCOOH > RCH₂OH
(b) RCH2NH2 > RCH₂OH > RCOOH
(c) R – CH₂OH > R – CH₂NH₂ > RCOOH
(d) R – COOH > R – CH₂OH > R – CH₂NH₂

Answer

Answer: d

---

24. Aniline is less basic than ethylamine. This is due to
(a) Conjugation of lone pair of nitrogen with the ring
(b) The insoluble nature of aniline
(c) More Kfc value of aniline
(d) Hydrogen bonding

Answer

Answer: a

---

25. Primary amine reacts with carbon disulphide and HgCl₂ to produce alkyl isothiocyanate. This reaction is
(a) Carbylanine reaction
(b) Hoffmann bromamide reaction
(c) Perkin reaction
(d) Hoffmann mustard oil reaction

Answer

Answer: d

---

26. Hinsberg’s reagent is

Answer

Answer: b

---

27. Nitration of aniline is carried out after acylation because
(a) Acylation dectivates the — NH₂ group
(b) Oxidation can be prevented
(c) O-and p-products are obtained in good yield
(d) All of these

Answer

Answer: d

---

28. NH₂ group in aniline is
(a) Ortho directing
(b) Meta directing
(c) Ortho and para directing
(d) Para directing

Answer

Answer: c

---

29. Primary and secondary amines cannot be distinguished by
(a) Schiff’s reagent
(b) Carbylamine reaction
(c) Hoffmann’s bromamide reaction
(d) Iodoform test

Answer

Answer: b

---

30. Which of the following cannot be identified by carbyl amine test?
1. C₂H₅NH₂
2. C₆H₅NH₂
3. C₆H₅ — NH — C₆H₅
4. (C₂H₅)₃N
(a) 1, 2
(b) 1, 2, 4
(c) 3, 4
(d) 2, 4

Answer

Answer: c

---

31.

Answer

Answer: b

---

32.
Here, Z is
(a) RCH₂ CH₂NH₂
(b) RCH₂NH₂
(c) RCH₂CONH₂
(d) RNH₂

Answer

Answer: b

---

Note: In the following questions two or more options may be correct. (Q.23 to Q.25)
33. Which of the following cannot be prepared by Sandmeyer’s reaction? [NCERT Exemplar]
(a) Chlorobenzene
(b) Bromobenzene
(c) Iodobenzene
(d) Fluorobenzene

Answer/Explanation

Answer:
Explaination:
(c) and (d). Iodobenzene and fluorobenzene can’t be prepared by Sandmeyer’s reaction.

---

34. The product of the following reaction is ____________ . [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a) and (b) because -NHCOCH₃ is o and -directing.

---

35. Under which of the following reaction conditions, aniline gives p-nitro derivative as the major product? [NCERT Exemplar]
(a) Acetyl chloride/pyridine followed by reaction with cone. H₂SO₄+ cone. HNO₃.
(b) Acetic anyhdride/pyridine followed by cone. H₂SO₄ + cone. HNO₃.
(c) Dil. HCl followed by reaction with cone. H₂SO₄ + cone. HNO₃.
(d) Reaction with cone. HNO₃ + cone. H₂SO₄.

Answer/Explanation

Answer:
Explaination:

---

36. Match the compounds given in Column I with the items given in Column II. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a) (ii)
(b) (i)
(c) (iv)
(d) (iii)

---

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (Q.27 and Q.28)
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct but reason is wrong statement.
(d) Assertion is wrong but reason is correct statement. –
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.
37. Assertion: Acetanilide is less basic than aniline. [NCERT Exemplar]
Reason: Acetylation of aniline results in decrease of electron density on nitrogen.

Answer/Explanation

Answer:
Explaination:
(a) Assertion and reason both are correct and reason is correct explanation of assertion.

---

38. Assertion: Only a small amount of HCl is required in the reduction of nitro compounds with iron scrap and HCl in the presence of steam. [NCERT Exemplar]
Reason: FeCl₂ formed gets hydrolysed to release HCl during the reaction.

Answer/Explanation

Answer:
Explaination:
(a) Assertion and reason both are correct and reason is correct explanation of assertion.

---

39. The pK_b of N,N-Dimethyl aniline is ____________ than aniline.

Answer/Explanation

Answer:
Explaination: lower

---

40. -OCH₃ ____________ the basic character of amines.

Answer/Explanation

Answer:
Explaination: increases

---

41. CH₃CH₂NH₂ has ____________ boiling point than (CH3)2NH.

Answer/Explanation

Answer:
Explaination: higher

---

42. The number of isomers of C₇H₉N are ____________ .

Answer/Explanation

Answer:
Explaination:

---

43. Tertiary amines do not react with Hinsberg’s reagent. [True/False]

Answer/Explanation

Answer:
Explaination:
True, because they do not have H attached to Nitrogen.

---

44. Tertiary amines form salt with HN02 soluble in water [True/False]

Answer/Explanation

Answer:
Explaination:
True. (CH₃)₃N + HNO₂ → (CH₃)₃NHNO₂

---

45. Aniline and ethyl amine can be distinguished by Azodye test. [True/False]

Answer/Explanation

Answer:
Explaination:
True. Aniline reacts with NaNO₂+ HC;l at 0°C to 5°C and with phenol to give orange azodye, ethyl amine does not.

---

46. Give the IUPAC name of H₂N—CH₂—CH₂—CH=CH₂.

Answer/Explanation

Answer:
Explaination:
But-3-en-1 -amine.

---

47. What is the structure and IUPAC name of the compound, allyl amine?

Answer/Explanation

Answer:
Explaination:

---

48. Give the common and IUPAC name of the compound:

Answer/Explanation

Answer:
Explaination:
3-Methylaniline or 3-Methylbenzenamine is IUPAC name. Common name is w-Toluidine.

---

49. Write the chemical equations for the following chemical reactions: A primary amine is prepared from a primary alkyl halide.

Answer/Explanation

Answer:
Explaination:
RX + NH₃ → RNH₂ + HX

---

50. How is aniline obtained from benzoic acid?

Answer/Explanation

Answer:
Explaination:

---

51. How is /n-nitroaniline obtained from nitrobenzene? [HOTS]

Answer/Explanation

Answer:
Explaination:

---

52. Out of CHJNHJ and (CH₃)₃N, which one has higher boiling point? [Delhi 2014(C)]

Answer/Explanation

Answer:
Explaination:
CH₃NH₂ has higher boiling point.3

---

53. Arrange the following compounds in increasing order of solubility in water:
C₆H₅NH₂, (C₂H₅)₂NH, C₂H₅NH₂ [Delhi 2014]

Answer/Explanation

Answer:
Explaination:
C₆H₅NH₂ < (C₂H₅)₂NH < C₂H₅NH₂ is the increasing order of solubility in water.

---

54. Why is an alkylamine more basic than ammonia? [Delhi 2011; Foreign 2011]

Answer/Explanation

Answer:
Explaination:
It is because alkyl groups are electron releasing in alkyl amines, they will increase electron density on ‘N’, therefore, they are more basic than NH₃.

---

55. Arrange the following compounds in an increasing order of basic strengths in their aqueous solutions:
NH₃, CH₃NH₂, (CH₃)₂NH, (CH₃)₃N [Delhi 2013,12]

Answer/Explanation

Answer:
Explaination:
(CH₃)₂NH > CH₃NH₂ > (CH₃)₃N > NH₃.

---

56. Which of the two is more basic and why? [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
CH₃NH₂ is more basic than aniline because in CH₃NH₂, —CH₃ group is electron releasing, which increases electron density on ‘N’, whereas inC₆H₅ group is electron withdrawing which decreases electron density on ‘N’.

---

57. Which of the two is more basic and why? [Similar to CBSE Sample Paper 2018; Foreign 2014]

Answer/Explanation

Answer:
Explaination:
p-Toluidine is more basic than aniline because —CH₃ group is electron releasing group and increases electron density on ‘N’.

---

58. Which of the two is more basic and why CH3NH2 or NH3? [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
CH₃NH₂ is more basic than NH₃ because methyl group is electron releasing which increases electron density on ‘N’.

---

59. Arrange the following in increasing order of basic strength:
C₆H₅NH₂, C₆H₅NHCH₃, C₆H₅N(CH₃)₂ [Delhi 2014]

Answer/Explanation

Answer:
Explaination:
C₆H₅NH₂ < C₆H₅NHCH₃ < C₆H₅N(CH₃)₂ is the increasing order of basic strength because —CH₃ group is electron releasing.

---

60. Arrange the following in increasing order of basic strength:
C₆H₅NH₂ > C₆H₅NHCH₃, C₆H₅CH₂NH₂ [Delhi 2014]

Answer/Explanation

Answer:
Explaination:
C₆H₅NH₂ < C₆H₅NHCH₃ < C₆H₅CH₂NH₂ is the increasing order of basic strength.

---

61. Arange in decreasing order of basic strength in gas phase:
C₂H₅NH₂, (C₂H₅)₂NH, (C₂H₅)₃N, NH₃

Answer/Explanation

Answer:
Explaination:
(C₂H₅)₃N > (C₂H₅)₂NH > C₂H₅NH₂ > NH₃

---

62. Arrange the following in increasing order of basic strength:
Aniline, p-Nitroaniline, p-Toludine [AI 2015(C)]

Answer/Explanation

Answer:
Explaination:
p-Nitroaniline < Aniline < p-Toludine

---

63. Why do amines react as nucleophiles?

Answer/Explanation

Answer:
Explaination:
It is due to presence of lone pair of electrons on nitrogen which they can donate and act as nucleophiles.

---

64. State the reaction taking place when: Bromine water is added to the aqueous solution of aniline. [Delhi 2016]

Answer/Explanation

Answer:
Explaination:

IUPAC name is 2,4,6 Tribromo benzenamine. [Delhi 2016]

---

65. An organic compound ‘A’ having molecular formula C₂H?N on treatment with HN02 gave an oily yellow substance. Identify ‘A’. [HOTS]

Answer/Explanation

Answer:
Explaination:

---

66. Complete the following reaction equation: [Delhi 2015(C)]
C₆H₅N₂CI + H₃PO₂ + H₂O →

Answer/Explanation

Answer:
Explaination:
C₆H₅N₂Cl + H₃PO₂ + H₂O → C₆H₆ + N₂ + HCl + H₃PO₃

---

67. Give a chemical test to distinguish between Aniline and Ethanamine. [Uttarakhand 2019]

Answer/Explanation

Answer:
Explaination:
Add NaNO₂ and HCl. Cool it to 0 – 5°C, then add alkaline solution of phenol. Aniline will form orange azodye whereas ethanamine does not.

---

68. Write one reaction that can be used as a test for primary amines. [Foreign 2011]

Answer/Explanation

Answer:
Explaination:
RNH₂ + CHCl₃ + 3KOH > R—N=ifC+ 3KCl + 3H₂O is used as a test for primary amine.
Alkyl carbylamine are olfensive smelling compounds.

---

69. Write a chemical reaction in which the iodide ion replaces the diazonium group in a diazonium salt.

Answer/Explanation

Answer:
Explaination:

---

70. Give the significance of coupling reaction of aryldiazonium salts.

Answer/Explanation

Answer:
Explaination:
Coupling reaction of aryldiazonium salts with phenol or arylamines involved in the formation of azo dyes.

---

We hope the given Chemistry MCQs for Class 12 with Answers Chapter 13 Amines will help you. If you have any query regarding CBSE Class 12 Chemistry Amines MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Chemistry Multiple Choice Questions for Class 12 with Answers Chapter 12 Aldehydes, Ketones, and Carboxylic Acids. Chemistry MCQs for Class 1 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Aldehydes, Ketones and Carboxylic Acids MCQs Pdf with Answers to know their preparation level.

Aldehydes, Ketones and Carboxylic Acids Class 12 Chemistry MCQs Pdf

Chemistry MCQ Questions for Class 12 Pdf Question 1.

Answer/Explanation

Answer: d
Explaination:

---

2. Reduction of aldehydes and ketones into hydrocarbons using zinc amalgam and cone. HCl is called:
(a) Cope reduction
(b) Dow reduction
(c) Wolff Kishner reduction
(d) Clemensen reduction

Answer/Explanation

Answer: d
Explaination:

---

Chemistry MCQs for Class 12 Chapter wise Pdf Question 3. Acetophenone when reacted with base C₂H₅—ONa, yields a stable product:

Answer/Explanation

Answer: d
Explaination:

---

Chemistry MCQs for Class 12 Chapterwise Question 4.

reacts with ch1oobenzene in presence of conc. H₂SO₄ produces

Answer/Explanation

Answer: c
Explaination:

---

Chemistry MCQs for Class 12 with Answers Pdf Question 5. Propanoic acid with Br₂/P₄ yields a dibromo product. The structure will be

Answer/Explanation

Answer: c
Explaination: (c) ∵ α-hydrogens are replaced by Br atoms.

---

Chemistry MCQs for Class 12 Question 6.

Answer/Explanation

Answer: b
Explaination:

---

7. CH₃CHO and C₆H₅ CH₂CHO can be distinguished chemically by
(a) Benedict’s test
(b) Iodoform test
(c) Tollen’s reagent test
(d) Fehling’s solution test

Answer/Explanation

Answer: b
Explaination:

---

8.

Answer/Explanation

Answer: c
Explaination:

---

9. Which is most reactive towards Nucleophilic substitution reaction?
(a) Benzaldehyde
(b) Acetophenone

Answer/Explanation

Answer: c
Explaination:
(c) ∵ Nitro group is electron withdrawing.

---

10. Which of the following is not soluble in NaHCO₃?
(a) 2, 4, 6-Trinitrophenol
(b) Benzoic acid
(c) o-Nitrophenol
(d) Benzene sulphonic acid

Answer/Explanation

Answer: c
Explaination: (c) o-Nitrophenol is weakly acidic.

---

11. A single compound of the structure

is obtained from ozonolysis of which of the following compound?

Answer/Explanation

Answer: c
Explaination:

---

12. Which among the given molecules can exhibit tautomerism?

(a) III only
(b) Both I and III
(c) Both I and II
(d) Both II and III

Answer/Explanation

Answer: a
Explaination:

---

13. The product formed by the reaction of an aldehyde with a primary amine is
(a) Carboxylic acid
(b) Aromatic acid
(c) SchifTs base
(d) Ketone

Answer/Explanation

Answer: c
Explaination:

---

14.

Answer/Explanation

Answer:
Explaination:

---

15. The correct order of increasing acidic strength is ____________ . [NCERT Exemplarl
(a) Phenol < Ethanol < Chloroacetic acid < Acetic acid
(b) Ethanol < Phenol < Chloroacetic acid < Acetic acid
(c) Ethanol < Phenol < Acetic acid < Chloroacetic acid
(d) Chloroacetic acid < Acetic acid < Phenol < Ethanol

Answer/Explanation

Answer: c
Explaination:
(c) It is because C₂H₅O^⊖ is least stable and chloroacetate ion is most stable.

---

16. Compound

can be prepared by the reaction of __________ . [NCERT Exemplar]
(a) Phenol and benzoic acid in the presence of NaOH
(b) Phenol and benzoyl chloride in the presence of pyridine
(c) Phenol and benzoyl chloride in the presence of ZnCl₂
(d) Phenol and benzaldehyde in the presence of palladium

Answer/Explanation

Answer:
Explaination:

---

17. Cannizaro’s reaction is not given by ____________ . [NCERT Exemplar]

Answer/Explanation

Answer: d
Explaination: (d) Because it has α-hydrogen.

---

Note: In the following questions two or more options may be correct. (Q.18 to Q.21)
18. Which of the following compounds do not undergo aldol condensation? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(b) and (d) because these do not have α-hydrogen.

---

19. Treatment of compound

with NaOH solution yields [NCERT Exemplar]
(a) Phenol
(b) Sodium phenoxide
(c) Sodium benzoate
(d) Benzophenone

Answer/Explanation

Answer:
Explaination:

---

20. Benzophenone can be obtained by ____________ . [NCERT Exemplar]
(a) Benzoyl chloride + Benzene + AlCl₃
(b) Benzoyl chloride + Diphenyl cadmium
(c) Benzoyl chloride + Phenyl magnesium chloride
(d) Benzene + Carbon monoxide + ZnCl₂

Answer/Explanation

Answer:
Explaination:

---

21. Correct order of decreasing reactivity of nucleophillic addition in case of HCHO, CH₃CHO and CH₃COCH₃ is
(a) CH₃ COH₃ > CH₃CHO > HCHO
(b) HCHO > CH₃CHO > CH₃COCH₃
(c) CH₃COCH₃ > HCHO > CH₃CHO
(d) CH₃CHO > HCHO > CH₃COCH₃

Answer

Answer: b

---

22. The reagent with which both acetaldehyde and acetone react easily is
(a) Fehling’s reagent
(b) Grignard’s reagent
(c) Schiff’s reagent
(d) Tollen’s reagent

Answer

Answer: b

---

23.
The above chemical reaction represents
(a) Rosenmund’s reaction.
(b) Cannizaro’s reaction.
(c) Kolbe’s reaction,
(d) Etard’s reaction.

Answer

Answer: b

---

24. For distinction between pentan-2-one and pentan-3-one, which reagent can be employed?
(a) K₂Cr₂O₇/H⁺
(b) ZnHg/HCl
(c) NaOH/I₂
(d) AgNO₃/NH₄OH

Answer

Answer: c

---

25. Which of the following will undergo aldol condensation?
(a) CH₂ = CHCHO
(b) CH = CCHO
(c) C₆H₅CHO
(d) CH₃CH₂CHO

Answer

Answer: d

---

26. Compound ‘A’ C₅H₁₀O forms a phenyl hydrazone and gives a negative Tollen’s reagent test and iodoform test. On reduction with Zn+Hg/HCl, compound A gives n-pentane. The compound ‘A’ is
(a) Primary alcohol
(b) Aldehyde
(c) Secondary alcohol
(d) Ketone

Answer

Answer: b

---

27. Tert Butyl alcohol can be obtained by treating with CH3MgBr followed by hydrolysis
(a) HCHO
(b) CH₃CHO
(c) CH₃COCH₃
(d) CH₃CH₂CHO

Answer

Answer: c

---

28.
(a) 3-Nitrosalicylic acid
(b) 3, 5-Dinitrosalicylic acid
(c) m-Nitrobenzoic acid
(d) Picric acid

Answer

Answer: d

---

29. The end product (C) in the following reaction sequence is

(a) CH₃ — CH₂ COONa
(b) CH₂ = CH₂
(c) CH₃ — CH₃
(d) CH₂ = CH-COOH

Answer

Answer: b

---

30. Benzone acid is weaker than ……… but stronger than ………..
(a) p-toluic acid, o-toluic acid
(b) p-nitrobenzoic acid, p-toluic acid
(c) acetic acid, formic acid
(d) fomic acid, acetic acid

Answer

Answer: d

---

31. Which of the following is the correct representation for intermediate of nucleophilic addition reaction to the given carbonyl compound (A): [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a) and (b) are correct intermediate.

---

32. Match the common names given in Column I with the IUPAC names given in Column II. [NCERT Exemplar]

Column I (Common names)	Column II (IUPAC names)
(a) Cinnamaldehyde	(i) Pentanal
(b) Acetophenone	(ii) Prop-2-enal
(c) Valeraldehyde	(iii) 4-Methylpent-3-en-2-one –
(d) Acrolein	(iv) 3-Phenylprop-2-enal
(e) Mesityl oxide	(v) 1-Phenylethanone

Answer/Explanation

Answer:
Explaination:
(a) (iv)
(b) (v)
(c) (i)
(d) (ii)
(e) (iii)

---

33. Match the acids given in Column I with their correct IUPAC names given in Column II. [NCERT Exemplar]

Column I (Acids)	Column II (IUPAC names)
(a) Phthalic acid	(i) Hexane-1,6-dioic acid
(b) Oxalic acid	(ii) Benzene-1,2-dicarboxylic acid
(c) Succinic acid	(iii) Pentane-1,5-dioic acid
(d) Adipic acid	(iv) Butane-1,4-dioic acid
(e) Glutaric acid	(v) Ethane-1,2-dioic acid

Answer/Explanation

Answer:
Explaination:
(a) (ii)
(b) (v)
(c) (iv)
(d) (i)
(e) (iii)

---

34. Match the reactions given in Column I with the suitable reagents given in Column II. [NCERT Exemplar]

Column I (Reactions)	Column II (Reagents)
(a) Benzophenone → Diphenylmethane	(i) LiAlH4
(b) Benzaldehyde → 1-Phenylethanol	(ii) DIBAL—H
(c) Cyclohexanone → Cyclohexanol	(iii) Zn(Hg)/Conc. HCl
(d) Phenyl benzoate → Benzaldehyde	(iv) CH3MgBr

Answer/Explanation

Answer:
Explaination:
(a) (iii)
(b) (iv)
(c) (i)
(d) (ii)

---

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (Q.25 to Q.28)
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct but reason is wrong statement.
(d) Assertion is wrong but reason is correct statement.
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.
35. Assertion: Formaldehyde is a planar molecule.
Reason: It contains sp² hybridised carbon atom. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a) Assertion and reason both are correct and reason is correct explanation of assertion.

---

36. Assertion: Compounds containing —CHO group are easily oxidised to corresponding carboxylic acids. Reason: Carboxylic acids can be reduced to alcohols by treatment with LiAlH4. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.

---

37. Assertion: The a-hydrogen atom in carbonyl compounds is less acidic.
Reason: The anion formed after the loss of a-hydrogen atom is resonance stabilised. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(d) Assertion is wrong but reason is correct statement.

---

38. Assertion: Aromatic aldehydes and formaldehyde undergo Cannizaro reaction.
Reason: Aromatic aldehydes are almost as reactive as formaldehyde. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(c) Assertion is correct but reason is wrong statement.

---

39. Pentan-2-one can be distinguished from pentan-3-one by ____________ test.

Answer/Explanation

Answer:
Explaination: Iodoform

---

40. The pKa of acetic acid is ____________ than that of phenol.

Answer/Explanation

Answer:
Explaination: lower

---

41. Benzoate ion is more ____________ than acetate ion.

Answer/Explanation

Answer:
Explaination: stable

---

42. Formic acid does not undergo HVZ reaction because it does not have ____________ .

Answer/Explanation

Answer:
Explaination: a-hydrogen

---

43. Phenol does not liberate CO₂ with NaHCO₃. [True/False]

Answer/Explanation

Answer:
Explaination: True, because it is weakly acidic.

---

44. All aldehydes turn SchifTs reagent pink. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

45.

Answer/Explanation

Answer:
Explaination: True

---

46. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

47. Write IUPAC name of the following compound: [Delhi 2014(C)]

Answer/Explanation

Answer:
Explaination: 2-Methyl propanal.

---

48. Write the structure of 3-hydroxybutanal. [Foreign 2013]

Answer/Explanation

Answer:
Explaination:

---

49. Write the structure of 3-methylbutanal. [Delhi 2013]

Answer/Explanation

Answer:
Explaination:

---

50. Write the IUPAC name of the compound. [Delhi 2014]

Answer/Explanation

Answer:
Explaination: 3-Amino butanal.

---

51. Write the IUPAC name of the following compound: [Chennai 2019]

Answer/Explanation

Answer:
Explaination:

---

52. Write the structure of the following compound: 3-oxopentanal. [Foreign 2011]

Answer/Explanation

Answer:
Explaination:

---

53. Write the structure of p-Methylbenzaldehyde molecule. [AI 2014; Delhi 2013]

Answer/Explanation

Answer:
Explaination:

---

54. Write the IUPAC name of the following compound: [Foreign 2014]

Answer/Explanation

Answer:
Explaination: 2-Hydroxy benzaldehyde.

---

55. Write the structure of 4-chloropentan-2-one. [AI 2014; Delhi 2013]

Answer/Explanation

Answer:
Explaination:

---

56. Write the structure of 4-methylpent-3-en-2-one. [Foreign 2013]

Answer/Explanation

Answer:
Explaination:

---

57. Write the IUPAC name of the compound. [Delhi 2014]

Answer/Explanation

Answer:
Explaination: 4-Hydroxy-2-pentanone.

---

58. Write the IUPAC name of [AI 2011(C)]

Answer/Explanation

Answer:
Explaination: 4-Methylpent-3-en-2-one

---

59. How will you convert 3-hydroxybutanal from ethanol? Write chemical reaction.

Answer/Explanation

Answer:
Explaination:

---

60. Complete the following chemical reaction:

Answer/Explanation

Answer:
Explaination:

---

61. Write the chemical equations for the following chemical reactions:
Benzonitrile is converted to acetophenone.

Answer/Explanation

Answer:
Explaination:

---

62. Ethanal is soluble in water. Why? [AI 2011]

Answer/Explanation

Answer:
Explaination:

---

63. Which aldehyde does not give Fehling’s solution test?

Answer/Explanation

Answer:
Explaination:

---

64. Write the IUPAC name of compound. [Delhi 2014]

Answer/Explanation

Answer:
Explaination:

---

65. Write the IUPAC name of the following: [Delhi 2011(C)]

Answer/Explanation

Answer:
Explaination:

---

66. Write the structure of 2-hydroxy benzoic acid. [AI 2014]

Answer/Explanation

Answer:
Explaination:

---

67. Write the structural formula of 2-phenylethanoic acid. [Foreign 2013]

Answer/Explanation

Answer:
Explaination:

---

68. Write the IUPAC name of [AI 2011(C)]

Answer/Explanation

Answer:
Explaination: 3-Bromo-5-chlorobenzoic acid

---

69. Write IUPAC name of the following compound: [AI 2014(C)]

Answer/Explanation

Answer:
Explaination: Isopropyl ethanoate (1-methyl ethyl propanoate).

---

70. Write the IUPAC name of [Delhi 2011(C)]

Answer/Explanation

Answer:
Explaination: 3, 5-Dimethylphenylethanoate

---

71. Higher carboxylic acids are practically insoluble in water. Give reason.

Answer/Explanation

Answer:
Explaination:
This is due to the increased hydrophobic interaction of hydrocarbon part.

---

72. Arrange the following in increasing order of acidic character:
HCOOH, ClCH₂COOH, CF₃COOH, CCl₃COOH

Answer/Explanation

Answer:
Explaination:
HCOOH < ClCH₂COOH < CCl₃COOH < CF₃COOH

---

73. Compare the strength of following acids:
(i) Formic acid,
(ii) Acetic acid,
(iii) Benzoic acid.

Answer/Explanation

Answer:
Explaination:
HCOOH > C₆H₅COOH > CH₃COOH

---

74. Give some industrial uses of methanoic acid.

Answer/Explanation

Answer:
Explaination:
It is used in rubber, textile, leather, dying and electroplating industries.

---

75. Draw the structural formula of 1-phenylpropan-l-one molecule.

Answer/Explanation

Answer:
Explaination:

---

We hope the given Chemistry MCQs for Class 12 with Answers Chapter 12 Aldehydes, Ketones and Carboxylic Acids will help you. If you have any query regarding CBSE Class 12 Chemistry Aldehydes, Ketones and Carboxylic Acids MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Chemistry Multiple Choice Questions for Class 12 with Answers Chapter 11 Alcohols, Phenols and Ethers. Chemistry MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Chemistry Alcohols, Phenols and Ethers MCQs Pdf with Answers to know their preparation level.

Alcohols, Phenols and Ethers Class 12 Chemistry MCQs Pdf

1. The heating of phenyl methyl ether with HI produces
(a) Iodobenzene
(b) Phenol
(c) Benzene
(d) Ethyl chloride

Answer/Explanation

Answer: b
Explaination:

---

2. Which of the following gives positive iodoform test?

Answer/Explanation

Answer: c
Explaination:

---

3.

Answer/Explanation

Answer: c
Explaination:

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4. CH3—O—CH (CH3)2 + HI → Products is/are

Answer/Explanation

Answer: d
Explaination:

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5.

The product ‘Z’ is
(a) Benzaldehyde
(b) Benzoic acid
(c) Benzene
(d) Toluene

Answer/Explanation

Answer: b
Explaination:

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6. Which one of the following compounds has the most acid nature?

Answer/Explanation

Answer: d
Explaination:
(d) Phenol is most acidic in nature because phenoxide ion is stabilized by resonance.

---

7. Among the following sets of reactants which one produces anisole?
(a) CH₃CHO : RMgX
(b) C₆H₅OH; NaOH, CH₃I
(c) C₆H₅OH, neutral FeCl₃
(d) C₆H₅ —CH₃; CH₃COCl; AlCl₃

Answer/Explanation

Answer: b
Explaination:

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8. The electrophile involved in Riemer-Tiemann reaction of phenol with CHCl₃ in presence of NaOH

Answer/Explanation

Answer: a
Explaination:

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9. Arrange the following in decreasing order of acidic character:

(a) IV > III > I > II
(b) II > IV > I > III
(c) I > II > III > IV
(d) III > I > II > IV

Answer/Explanation

Answer: d
Explaination:
(d) – Since, N02 and Cl are electron withdrawing but NO₂ > Cl.
– OCH₃ is more electron releasing due to +R effect than —CH₃ group, therefore, IV is least acidic.

---

10.

(a) Etard reaction
(b) Gattermann Koch reaction
(c) Williamson synthesis
(d) Esterification

Answer/Explanation

Answer: c
Explaination:
(c) Williamson synthesis.

---

11. Identify ‘C’ in the following:

(a) Water
(b) Ethanol
(c) Propanone
(d) Cumene hydroperoxide

Answer/Explanation

Answer: c
Explaination:

---

12.

Answer/Explanation

Answer: a
Explaination:

---

13. Find the product of the given reaction:

Answer/Explanation

Answer: a
Explaination:

---

14.

Answer/Explanation

Answer: b
Explaination:

---

15. Monochlorination of toluene in sunlight followed by hydrolysis with aq. NaOH yields. [NCERT Exemplar]
(a) o-Cresol
(b) m-Cresol
(c) 2, 4-Dihydroxytoluene
(d) Benzyl alcohol

Answer/Explanation

Answer: a
Explaination:

---

16. How many alcohols with molecular formula C₄H₁₀O are chiral in nature? [NCERT Exemplar]
(a) 1
(b) 2
(c) 3
(d) 4

Answer/Explanation

Answer: a
Explaination:

---

17. What is the correct order of reactivity of alcohols in the following reaction? [NCERT Exemplar]

(a) 1° > 2° > 3°
(b) P < 2° > 3°
(c) 3° > 2° > 1°
(d) 3° > 1° > 2°

Answer/Explanation

Answer: c
Explaination:
(c) 3° >2° > 1° is order of stability of carbocation .’. Reactivity follows the same order.

---

18. CH₃CH₂OH can be converted into CH₃CHO by __________ . [NCERT Exemplar]
(a) catalytic hydrogenation
(b) treatment with LiAlH₄
(c) treatment with pyridinium chlorochromate
(d) treatment with KMnO₄

Answer/Explanation

Answer: c
Explaination:

---

19. IUPAC name of the compound

is _________ . [NCERT Exemplar]
(a) 1-methoxy-l-methylethane
(b) 2-methoxy-2-methylethane
(c) 2-methoxypropane
(d) isopropylmethyl ether

Answer/Explanation

Answer: c
Explaination:
(c) 2-methoxypropane

---

20. Which of the following species can act as the strongest base?

Answer/Explanation

Answer: b
Explaination:
(b) ∵ ROH is weakest acid,
∴ RO^⊖ is strongest conjugate base.

---

21. The correct order of boiling point of primary (1°), secondary (2°) and tertiary (3°) alcohols is
(a) 1° > 2° > 3°
(b) 3° > 2° > 1°
(c) 2° > 1° > 3°
(d) 2° > 3° > 1°

Answer

Answer: a

---

22.
The above reaction is known as
(a) Williamson’s reaction.
(b) Hofmann’s synthesis.
(c) Mendies reaction,
(d) Darzen’s reaction.

Answer

Answer: d

---

23. The correct acidic strength order of the following

(a) I > II > III
(b) III > I > II
(c) II > III > I
(d) I > III > II

Answer

Answer: b

---

24. Which compound is predominantly formed when phenol is allowed to react with bromine in aqueous medium?
(a) Picric acid
(b) O-Bromophenol
(c) 2, 4, 6-Tribromophenol
(d) p-Bromophenol

Answer

Answer: c

---

25. Phenols are more acidic than alcohols because
(a) Phenoxide ion is stablised by resonance
(b) Phenols are more soluble in polar solvents
(c) Phenoxide ion does not exhibit resonance
d) Alcohols do not lose H atoms at all

Answer

Answer: a

---

26. The compound B is formed in the sequence of the reaction given below:

The compound B is
(a) Salicylaldehyde
(b) Benzoic acid
(c) Salicylic acid
(d) Cinnamic acid

Answer

Answer: c

---

27. Which of the following reagents cannot be used to distinguish between phenol and benzyl alcohol?
(a) FeCl₃
(b) Litmus soln
(c) Br₂/CCl₄
(d) All of these

Answer

Answer: c

---

28. Identify Z in the series

Answer

Answer: d

---

29. 1-propanol and 2-propanol can be best dis¬tinguished by
(a) Oxidation with KMnO₄ followed by reaction with Fehling solution.
(b) Oxidation with acidic dichromate followed by reaction with Fehling solution.
(c) Oxidation by heating with copper followed by reaction with Fehling solution.
(d) Oxidation with concentrated H₂SO₄ followed by reaction with Fehling solution.

Answer

Answer: c

---

30.
In the above sequence Z is
(a) Toluene
(b) Cresol
(c) Benzene
(d) Benzol

Answer

Answer: c

---

31. The major organic product in the reaction, CH₃ — O — CH(CH₃)₂ + HI → product: is/are

Answer

Answer: a

---

Note: In the following questions two or more options may be correct. (Q.21 to Q.23)
32. Which of the following are used to convert RCHO into RCH₂OH? [NCERT Exemplar]
(a) H₂/Pd
(b) LiAlH₄
(c) NaBH₄
(d) Reaction with RMgX followed by hydrolysis

Answer/Explanation

Answer:
Explaination:
(a), (b), (c) will convert RCHO into RCH₂OH.

---

33. Which of the following reactions will yield phenol? [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(a), (b), (c) will give phenol, (d) will not give phenol because high temperature is needed.

---

34. Which of the following reagents can be used to oxidise primary alcohols to aldehydes? [NCERT Exemplar]
(a) CrO₃ in anhydrous medium.
(b) KMnO₄ in acidic medium.
(c) Pyridinium chlorochromate.
(d) Heat in the presence of Cu at 573K.

Answer/Explanation

Answer:
Explaination:
(a), (c), (d) can be used. KMnO⁴ converts primary alcohol to carboxylic acids.

---

35. Match the structures of the compounds given in Column I with the name of the compounds given in Column II. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(i) (d) (ii) (c) (iii) (J) (iv) (a) or quinol (v) (g) (vi) (b)

---

36. Match the starting materials given in Column I with the products formed by these (Column II) in the reaction with HI. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(i) (d) (ii) (e) (iii) (b) (iv) (a)
In cleavage of ethers, higher alcohol and lower alkyl halide is formed except in tert. butyl methyl ether, in which (CH₃)₃ C+ is more stable so (CH₃)₃C-I and CH₃OH is formed. Anisole with HI gives phenol and CH₃I because phenoxide ion is stabilised by resonance.

---

37. In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(e) Both assertion and reason are correct statements but reason is not correct explanation of assertion.
Assertion: Bond angle in ethers is slightly less than the tetrahedral angle.
Reason: There is a repulsion between the two bulky (—R) groups. [NCERT Exemplar]

Answer/Explanation

Answer:
Explaination:
(d) Assertion is wrong statement but reason is correct statement.

---

38. Phenol reacts with Br₂ in CS₂ to give _________ as major product.

Answer/Explanation

Answer:
Explaination: p-bromophenol

---

39. Phenol gives o and p-nitrophenol with _________ .

Answer/Explanation

Answer:
Explaination: dil. HNO₃

---

40. o-nitrophenol has _________ melting point than /j-nitrophenol.

Answer/Explanation

Answer:
Explaination: lower

---

41. Diethyl ether has dipole moment because they are bent molecule. [True/False]

Answer/Explanation

Answer:
Explaination: True

---

42. Ethers have lower boiling point than alcohol. [True/False]

Answer/Explanation

Answer:
Explaination:
True. It is due to weak van der Waals’ forces of attraction in ethers but intermolecular H-bonding in alcohol.

---

43. Dettol contains phenolic compound. [True/False]

Answer/Explanation

Answer:
Explaination: True, phenols are antiseptic in low concentration.

---

44. Write the IUPAC name of the given compound: [Foreign 2015]

Answer/Explanation

Answer:
Explaination: 3-methyl but-2-en-1-ol.

---

45. Write the IUPAC name of the given compound: [AI2015]

Answer/Explanation

Answer:
Explaination: 2-methyl propane 1, 3-diol.

---

46. Write the IUPAC name of the following compound: [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Hex-4-en-3-ol.

---

47. Write IUPAC name of the following:

Answer/Explanation

Answer:
Explaination: 2, 2-Dimethyl propan-l-ol.

---

48. Write the IUPAC name of the following: [AI 2015 Bhubneshwar]

Answer/Explanation

Answer:
Explaination: l-Phenylpropan-2-ol.

---

49. Write IUPAC name of the compound: [Delhi 2015(C)]

Answer/Explanation

Answer:
Explaination: Butan-2-ol

---

50. Write IUPAC name of the given compound: [AI 2015 Patna]

Answer/Explanation

Answer:
Explaination: 2-methyl prop-2-en-l-ol.

---

51. Draw the structural formula of 2-methylpropan-2-ol molecule. [Delhi 2012]

Answer/Explanation

Answer:
Explaination:

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52. Draw the structure of hex-l-en-3-ol compound.

Answer/Explanation

Answer:
Explaination:

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53. How is ethanol obtained from 2-butene? [Delhi 2012]

Answer/Explanation

Answer:
Explaination:

---

54. Write the IUPAC name of the given compound: [Delhi 2015]

Answer/Explanation

Answer:
Explaination: 2, 5-Dinitro phenol.

---

55. Write IUPAC name of the given compound: [AI 2015 Guwahati]

Answer/Explanation

Answer:
Explaination: 2, 4-Dimethyl phenol.

---

56. Draw the structure of 2, 6-dimethylphenol. [AI 2011]

Answer/Explanation

Answer:
Explaination:

---

57. Write the IUPAC name of the given compound: [AI 2015]

Answer/Explanation

Answer:
Explaination:

---

58. Write IUPAC name of the given compound: [AI 2015 Chennai and Trivandrum]

Answer/Explanation

Answer:
Explaination: 1-Methoxypropan-2-ol.

---

59. Write the structure of the following compound: 2-ethoxy-2-methyl pentane

Answer/Explanation

Answer:
Explaination:

---

60. How is /-butyl alcohol obtained from acetone?

Answer/Explanation

Answer:
Explaination:

---

61. Write the chemical equation for the preparation of phenol from benzene using oleum and sodium hydroxide. [Delhi 2011(C)]

Answer/Explanation

Answer:
Explaination:

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62. Why alcohols and phenols are soluble in water?

Answer/Explanation

Answer:
Explaination: This is due to their ability to form hydrogen bonds with water molecules.

---

63. Which of the following isomers is more volatile: o-nitrophenol or p-nitrophenol? [Delhi 2014]

Answer/Explanation

Answer:
Explaination: o-nitrophenol is more volatile, cone. H₂SO₄

---

64. How would you convert ethanol to ethene? [AI 2011]

Answer/Explanation

Answer:
Explaination:

---

65. Name a compound which is used as antiseptic as well as disinfectant.

Answer/Explanation

Answer:
Explaination:
0.2% solution of phenol is used as antiseptic, 2% solution of phenol is used as disinfectant.

---

66. Arrange the following in decreasing order of their acidic character: [Similar to AI 2017]

Answer/Explanation

Answer:
Explaination: (ii) > (iii) > (i)

---

67. Illustrate with examples the limitations of Williamson’s synthesis for the preparation of certain types of ethers.

Answer/Explanation

Answer:
Explaination:
Di-tertiary butyl ether cannot be prepared by Williamson’s synthesis because tertiary halides will undergo elimination reaction instead of substitution reaction.

---

68. What is the cause of large difference in boiling points of alcohols and ethers?

Answer/Explanation

Answer:
Explaination:
This is due to the presence of hydrogen bonding in alcohols but ether have weak van der Waals’ forces of attraction.

---

69. Convert anisole to p-bromoanisole. [Delhi 2015(C)]

Answer/Explanation

Answer:
Explaination:

---

70. How will you synthesise the following from appropriate alkene: [Uttarakhand 2019]

Answer/Explanation

Answer:
Explaination:

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71. Show how you will synthesise the following alcohol prepared by reaction of a suitable Grignard reagent on methanal? [Uttarakhand 2019]

Answer/Explanation

Answer:
Explaination:

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We hope the given Chemistry MCQs for Class 12 with Answers Chapter 11 Alcohols, Phenols, and Ethers will help you. If you have any query regarding CBSE Class 12 Chemistry Alcohols, Phenols, and Ethers MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Physics Multiple Choice Questions for Class 12 with Answers Chapter 14 Semiconductor Electronics: Materials, Devices and Simple Circuits. Physics MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Physics Semiconductor Electronics: Materials, Devices and Simple Circuits MCQs Pdf with Answers to know their preparation level.

Semiconductor Electronics: Materials, Devices and Simple Circuits Class 12 Physics MCQs Pdf

Class 12 Physics MCQ Question 1. In the given figure V0 is the potential barrier across a p-n junction, when no battery is cdnnected across the junction. [NCERT Exemplar]

(a) 1 and 3 both correspond to forward bias of junction.
(b) 3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction.
(c) 1 corresponds to forward bias and 3 corresponds to reverse bias of junction.
(d) 3 and 1 both correspond to reverse bias of junction.

Answer/Explanation

Answer: b
Explanation:
(b) Height of potential barrier is decreases when p-n junction is forward bias.

---

Physics MCQs Pdf Question 2. In figure given, assuming the diodes to be ideal [NCERT Exemplar]

(a) D₁ is forward biased and D₂ is reverse biased and hence current flows from A to B.
(b) D₂ is forward biased and D₁ is reverse biased and hence no current flows from B to A and vice versa.
(c) D₁ and D₂ are both forward biased and hence current flows from A to B.
(d) D₁ and D₂ are both reverse biased and hence no current flows from A to B and vice versa.

Answer/Explanation

Answer: b
Explaination:
(b) Explanation:
10 V is the lower voltage in the circuit. Now p side of the p-n junction diode D₁ is connected to lower voltage and n- side of D₁ to higher voltage , thus D₁, is reverse biased. In D₂ p-side of p-n junction diode is at higher potential and n-side is at lower potential, therefore D₂ is forward biased. Hence current flows through junction from B to A.

---

3. The output of the given circuit in figure is given below. [NCERT Exemplar]

(a) would be zero at all times.
(b) would be like a half-wave rectifier with positive cycles in output.
(c) would be like a half-wave rectifier with negative cycles in output.
(d) would be like that of a full-wave rectifier.

Answer/Explanation

Answer: c
Explaination:
(c) Explanation:
When the diode is forward biased, the resistance of pn junction diode will be low then current in the circuit is maximum. In this situation, a maximum potential difference will appear across resistance connected in a series of circuit. This result into zero

---

Semiconductor Numericals Class 12 Question 4. Electrical conductivity of a semiconductor
(a) decreases with the rise in its temperature.
(b) increases with the rise in its temperature.
(c) does not change with the rise in its temperature.
(d) first increases and then decreases with the rise in its temperature

Answer/Explanation

Answer:
Explaination:
(b) With temperature rise, the conductivity of semiconductor increases.

---

5. The forbidden energy band gap in conductors, semiconductors and insulators are EG₁,EG₂ and EG₃ respectively. The relation among them is
(a) EG₁ = EG₂ = EG₃
(b) EG₁ < EG₂ < EG₃
(c) EG₁ > EG₂ > EG₃
(d) EG₁ < EG₂ > EG₃

Answer/Explanation

Answer:
Explaination:
(b) In insulators, the forbidden energy gap is very large, in case of semiconductor it is moderate and in conductors the energy . gap is zero.

---

MCQ Physics Class 12 Question 6. In an insulator, the forbidden energy gap between the valence band and the conduction band is of the order of __________ .

Answer/Explanation

Answer:
Explaination: 5 eV

---

Semiconductor Class 12 Question 7. A n-type semiconductor is
(a) negatively charged.
(b) positively charged.
(c) neutral.
(d) none of these

Answer/Explanation

Answer: c
Explaination:
(c) n-type semiconductors are neutral because neutral atoms are added during doping.

---

8. In the half-wave rectifier circuit shown. Which one of the following waveforms is true for V_CD the output across C and D?

Answer/Explanation

Answer: b
Explaination:
(b) Half wave rectifier rectifies only the half cycle of the input ac signal and it blocks the other half.

---

9. A full-wave rectifier circuit along with the input and output voltages is shown in the figure The contribution to output voltage from diode 2 is

(a) A, C
(b) B, D
(c) B, C
(d) A, D

Answer/Explanation

Answer: b
Explaination:
(b) In the positive half cycle of input ac signal diode D₁ is forward biased and D₂ is reverse biased so in the output voltage signal, A and C are due to D₁. In negative half cycle of input ac signal, D2 conducts, hence output signals B and D are due to D₂

---

10. A 220 V AC supply is connected between points A and B (figure). What will be the potential difference V across the capacitor? [NCERT Exemplar]

(a) 200 V
(b) 110 V
(c) 0 V
(d) 220√2 V

Answer/Explanation

Answer: d
Explaination:
(d) As p-n junction diode will conduct during positive half cycle only and during negative half cycle diode is reverse biased. During this diode will not give any output. So potential difference across the capacitor C = peak voltage of the given AC voltage.
V_o=V_rms√2 = 200√2 V.

---

MCQ Semiconductor Physics Question 11. In the circuit shown in figure below, if the diode forward voltage drop is 0.3 V, the voltage difference between A and B is [NCERT Exemplar]

(a) 1.3 V
(b) 2.3 V
(c) 0
(d) 0.5 V

Answer/Explanation

Answer: b
Explaination:
(b) Suppose the potential difference be¬ tween A and B is V_AB.
Then,V_AB – 0.3
= [(r₁ + r₂)10³] × (0.2 × 10^-3) [∵ V_AB=ir]
= [(5 + 5)10³] × (0.2 × 10^-3)
= 10 × 10³ × 0.2 × 10^-3 = 2
⇒ V_AB = 2 + 0.3 = 2.3V

---

12. When an electric field is applied across a semicoriductor [NCERT Exemplar]
(a) holes move from lower energy level to higher energy level in the conduction band.
(b) electrons move from higher energy level to lower energy level in the conduction band.
(c) holes in the valence band move from higher energy level to lower energy level.
(d) holes in the valence band move from lower energy level to higher energy level.

Answer/Explanation

Answer: c
Explaination:
(c) When electric field is applied across a semiconductor, the electrons in the con-duction band move from lower energy level to higher energy level. While the holes in valence band move from higher energy level to lower energy level, where they will be having more energy.

---

13. At absolute zero, Si acts as a
(a) metal
(b) semiconductor
(c) insulator
(d) none of these

Answer

Answer: c

---

14. In good conducrors of electricity the type of bonding that exist is
(a) Van der Walls
(b) covalent
(c) ionic
(d) metallic

Answer

Answer: d

---

15. The manifestation of band structure in solids is due to
(a) Heisenberg uncertainty priniciple
(b) Pauli’s exclusion principle
(c) Bohr’s correspondence principle
(d) Boltzmann law

Answer

Answer: b

---

16. The probability of electrons to be found in the conduction band of an intrinsic semiconductor of finite temperature
(a) increases exponentially with increasing band gaP
(b) decreases exponentially with increasing band gap
(c) decreases with increasing temperature.
(d) is independent of the temperature and band gap

Answer

Answer: b

---

17. In an n-type silicon, which of the following statements is true.
(a) Electrons are majority carriers and trivalent atoms are the dopants’
(b) Electrons are minority carriers and pentava- lent atoms are the dopants.
(c) Holes are minority carriers and pentavalent atoms are the dopants.
(d) Holes are majority carriers and trivalent atoms are the dopants.

Answer

Answer: c

---

18. If a small amount of antimony is added to germanium crystal
(a) its resistance is increased
(b) it becomes a p-type semiconductor
(c) there will be more free electrons than holes in the semiconductor,
(d) none of these.

Answer

Answer: c

---

Semiconductor Electronics Question 19. The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are
(a) drift in forward bias, diffusion in reverse bias
(b) diffusion in forward bias, drift in reverse bias
(c) diffusion in both forward and reverse bias
(d) drift in both forward and reverse bias

Answer

Answer: b

---

20. In an unbiased p-n junction, holes diffuse from the p-region to n-region because
(a) free electrons in the n-region attract them
(b) they move across the junction by the potential difference
(c) hole concentration in p-region is more as compared to u-region.
(d) all of these

Answer

Answer: c

---

21. Region without free electrons and holes in a p-n junction is
(a) n-region
(b) p-region
(c) depletion region
(d) none of these

Answer

Answer: c

---

22. Which of the following statements is incorrect for the depletion region of a diode?
(a) There the mobile charges exist.
(b) Equal number of holes and electrons exist, making the region neutral.
(c) Recombination of holes and electrons has taken place.
(d) None of these

Answer

Answer: a

---

23. Potential barrier developed in a junction diode opposes the flow of
(a) minority carrier in both regions only
(b) majority carriers only
(c) electrons in p region
(d) holes in p region

Answer

Answer: b

---

24. The breakdown in a reverse biased p-n junction diode is more likely to occur due to
(a) large velocity of the minority charge carriers if the doping concentration is small
(b) large velocity of the minority charge carriers if the doping concentration is large
(c) strong electric field in a depletion region if the doping concentration is small
(d) none of these

Answer

Answer: b

---

25. What happens during regulation action of a Zener diode?
(a) The current through the series resistance (Rs) changes.
(b) The resistance offered by the Zener changes.
(c) The Zener resistance is constant.
(d) Both (a) and (b)

Answer

Answer: d

---

26. A zener diode is specified as having a breakdown voltage of 9.1 V, with a maximum power dissipation of 364 mW. What is the maximum current the diode can handle?
(a) 40 mA
(b) 60 mA
(c) 50 mA
(d) 45 mA

Answer

Answer: a

---

27. In a half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
(a) 25 Hz
(b) 50 Hz
(c) 70.7 Hz
(d) 100 Hz

Answer

Answer: b

---

28. In the circuit shown if current for the diode is 20 μA, the potential difference across the diode is

(a) 2 V
(b) 4.5 V
(c) 4 V
(d) 2.5 V

Answer

Answer: c

---

29. Carbon, silicon and germanium have four valence electrons each. These are characterised by valence and conduction bands separated by energy band gap respectively equal to (E^)c, (Eg)Si and (Eg)Ge. Which of the following statements is true?
(a) (E_g)_Si < (E_g)_Ge < (E_g)_C
(b) (E_g)_C< (E_g)_Ge < (E_g)_Si
(c) (E_g)_C < (E_g)_Si < (E_g)_Ge
(d) (E_g)_C = (E_g)_Si < (E_g)_Ge

Answer

Answer: c

---

30. If the energy of a photon of sodium light (A = 589 nm) equals the band gap of semiconductor, the minimum energy required to create hole electron pair
(a) 1.1 eV
(b) 2.1 eV
(c) 3.2 eV
(d) 1.5 eV

Answer

Answer: b

---

31. If in a n-type semiconductor when all donor states are filled, then the net charge density in the donor states becomes
(a) 1
(b) > 1
(c) < 1, but not zero
(d) zero

Answer

Answer: b

---

Physics MCQs for Class 11 with Answers Pdf Question 32. The circuit has two oppositely connected ideal diodes in parallel. What is the current flowing in the circuit?

(a) 2.0 A
(b) 1.33 A
(c) 1.73 A
(d) 2.31 A

Answer

Answer: c

---

33. The conductivity of a semiconductor increases with increase in temperature, because
(a) number density of free current carriers increases.
(b) relaxation time increases.
(c) both number density of carriers and relaxation time increase.
(d) number density of carriers increases, relaxation time decreases but effect of decrease in relaxation time is much less than increase in number density. [NCERT Exemplar]

Answer

Answer: d

---

34. What happens during regulation action of a Zener diode? [NCERT Exemplar]
(a) The current in and voltage across the Zener remains fixed.
(b) The current through the series resistance (R_s) does not change.
(c) The Zener resistance is constant.
(d) The resistance offered by the Zener changes.

Answer

Answer: d

---

35. Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity _________ .

Answer/Explanation

Answer:
Explaination: increases

---

36. When the electrical conductivity of a semiconductor is due to the breaking of its covalent bonds, then the semiconductor is said to be ___________ .

Answer/Explanation

Answer:
Explaination: intrinsic

---

37. Why are the elemental dopants mainly taken from 13th and 15th group, for doping Silicon or Germanium?

Answer/Explanation

Answer:
Explaination:
The dopant has to be such that it does not distort the original pure semiconductor lattice. So that the sizes of the dopant and the semiconductor atoms should be nearly the same.

---

38. What is a hole? What is its physical significance?

Answer/Explanation

Answer:
Explaination:
Hole is the vacancy of electron in valence band. The vacancy with the hole behaves as an apparent free particle with effective positive charge.

---

39. Name one impurity each, which when added, to pure Si, produces
(i) n-type, and
(ii)p-type semiconductor.

Answer/Explanation

Answer:
Explaination:
(i) for n-type, arsenic.
(ii) for p-type, Indium.

---

40. Why is the conductivity of n-type semi-conductor greater than that of the p-type semi-conductor even when both of these have same level of doping?

Answer/Explanation

Answer:
Explaination:
In n-type semiconductor charge carriers are electrons and mobility of electrons is more than that of holes.

---

41. Name two factors on which electrical conductivity of a pure semiconductor at a given temperature depends.

Answer/Explanation

Answer:
Explaination:
(i) Band gap
(ii) Biasing.

---

42. What is an ideal diode?

Answer/Explanation

Answer:
Explaination:
It is a p-n junction diode which offer zero resistance in forward biasing and infinite re-sistance in reverse biasing, i.e. current flows through it in one direction only.

---

43. What happens to the width of depletion layer of ap-n junction when it is
(i) forward biased,
(ii) reverse biased? [AI2011]

Answer/Explanation

Answer:
Explaination:
(i) The width of depletion layer decreases.
(ii) The width of depletion layer increases.

---

44. What do you understand by a dynamic resistance of p-n junction diode.

Answer/Explanation

Answer:
Explaination:
Dynamic resistance is the ratio of a small change in voltage ΔV to a small change in current ΔI, i.e.\(\frac{\Delta V}{\Delta I}\).

---

45. Name the junction diode whose I – V characteristics are drawn below. [Delhi 2017]

Answer/Explanation

Answer:
Explaination: Solar cell.

---

46. State the reason, why GaAs is most commonly used in making of a solar cell.

Answer/Explanation

Answer:
Explaination: It has higher absorption coefficient.

---

47. Name the type of biasing of a p-n junction diode so that the junction offers very high resistance.

Answer/Explanation

Answer:
Explaination: Reverse biasing.

---

48. What is internal field emission?

Answer/Explanation

Answer:
Explaination:
The emission of electrons from the host atoms present in the p-n junction due to the high electric field is known as internal field emission or field ionisation.

---

Semiconductor Class Question 49. Why is a typical solar cell drawn in fourth quadrant?

Answer/Explanation

Answer:
Explanation:
I – V characteristics of solar cell is drawn in the fourth quadrant because a solar cell does not draw current but supplies the same to the load.

---

50. Why are materials like CdS or CdSe (E_g ~ 2.4 eV) not used for the fabrication of a solar cell?

Answer/Explanation

Answer:
Explaination:
Materials like CdS or CdSe (E_g ~ 2.4 eV) are not used because they will use only the high energy component of the solar energy for photo-conversion and a significant part of energy will be of no use.

---

We hope the given Physics MCQs for Class 12 with Answers Chapter 13 Semiconductor Electronics: Materials, Devices and Simple Circuits will help you. If you have any query regarding CBSE Class 12 Physics Semiconductor Electronics: Materials, Devices and Simple Circuits MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Free PDF Download of CBSE Physics Multiple Choice Questions for Class 12 with Answers Chapter 13 Nuclei. Physics MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Physics Nuclei MCQs Pdf with Answers to know their preparation level.

Nuclei Class 12 Physics MCQs Pdf

Atoms and Nuclei Class 12 MCQ Question 1. When a β-particle is emitted from a nucleus then its neutron-proton ratio
(a) increases
(b) decreases
(c) remains unchanged.
(d) may increase or decrease depending upon the nucleus.

Answer/Explanation

Answer: b
Explaination:
(b) In P-decay neutron converts to proton with emission of electron and neutrino.

---

Physics MCQs with Answers for Class 12 Question 2. The relation between half-life T_1/2 of a radioactive sample and its mean life x is

Answer/Explanation

Answer: a
Explaination:

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3. The quantity which is not conserved in a nuclear reaction is
(a) momentum.
(b) charge.
(c) mass.
(d) none of these.

Answer/Explanation

Answer: c
Explaination: (c) Energy equivalent to mass detect is released.

---

4. The half-life of a radioactive nucleus is 3 hours. In 9 hours, its activity will be reduced to a factor of

Answer/Explanation

CBSE Class 12 Physics MCQs with Answer: d
Explaination:

---

MCQs Of Physics 2nd Year with Answers Chapter 13 Question 5. A radioactive element has half-life period 1600 years. After 6400 years what amount will remain?

Answer/Explanation

Answer: b
Explaination:

---

Class 12 Physics MCQs Pdf Question 6. Ratio of the radii of the nuclei with mass numbers 8 and 27 would be

Answer/Explanation

Answer: c
Explaination:

---

7. A radioactive nucleus emits a beta particle. The parent and daughter nuclei are
(a) isotopes
(b) isotones
(c) isomers
(d) isobars

Answer/Explanation

Answer: d
Explaination:
(d) Isobars have the same atomic mass but 1 different atomic number.

---

Physics MCQs for Class 11 Chapter wise Pdf Question 8. In the disintegration series

the values of Z and A respectively will be
(a) 92, 236
(b) 88, 230
(c) 90, 234
(d) 91, 234

Answer/Explanation

Answer: d
Explaination:

---

CBSE Class 12 Physics MCQ Pdf Question 9. A nucleus \(_{Z}^{\mathbf{A}} \mathbf{X}\) emits an α-particle. The resultant nucleus emits a β-particle. The respective atomic and mass numbers of the daughter nucleus will be
(a) Z – 3, A – 4
(b) Z – 1, A – 4
(c) Z – 2, A – 4
(d) Z, A – 2

Answer/Explanation

Answer: b
Explaination:

---

10. In the nuclear reaction

What does X stand for?
(a) Electron
(b) Proton
(c) Neutron
(d) Neutrino

Answer/Explanation

Answer: d
Explaination:
(d) By conservation of mass A = 0, and by conservation of charge Z = 0, Hence X is neutrino.

---

11. The set which represent the isotope, isobar, and isotone respectively is

Answer

Answer: d

---

12. The mass number of iron nucleus is 56 the nuclear density is
(a) 2.29 × 10¹⁶ kg m^-3
(b) 2.29 × 10¹⁷ kg m^-3
(c) 2.29 × 10¹⁸ kg m^-3
(d) 2.29 × 10¹⁵ kg m^-3

Answer

Answer: b

---

13. Order of magnitude of density of uranium nucleus is
(a) 10²⁰ kg m^-3
(b) 10¹⁷ kg m^-3
(c) 10¹⁴ kg m^-3
(d) 10¹¹ kg m^-3

Answer

Answer: b

---

14. The radius of a spherical nucleus as measured by electron scattering is 3.6 fm. What is the mass number of the nucleus most likely to be?
(a) 27
(b) 40
(c) 56
(d) 120

Answer

Answer: a

---

15. The half life of a radioactive susbtance is 30 days. What is the time taken to disintegrate to 3/4^th of its original mass?
(a) 30 days
(b) 15 days
(c) 60 days
(d) 90 days

Answer

Answer: c

---

16. The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an
(a) isomer of parent
(b) isotone of parent
(c) isotope of parent
(d) isobar of parent

Answer

Answer: c

---

17. During negative β-decay, an antineutrino is also emitted along with the emitted electron. Then,
(a) only linear momentum will be conserved
(b) total linear momentum and total angular momentum but not total energy will be conserved
(c) total linear momentum, and total energy but not total angular momentum will conserved
(d) total linear momentum, total angular momentum and total energy will be conserved

Answer

Answer: d

---

18. Consider α and β particles and γ-rays each having an energy of 0.5 MeV. In the increasing order of penetrating power, the radiation are respectively
(a) α, β, γ
(b) α, γ, β
(c) β, γ, α
(d) γ β, α

Answer

Answer: a

---

19. An electron emitted in beta radiation originates from
(a) inner orbits of atom
(b) free electrons existing in the nuclei
(c) decay of a neutron in a nuclei
(d) photon escaping from the nucleus

Answer

Answer: c

---

20. Complete the series 6He → e^– + ⁶Li +
(a) neutrino
(b) antineutrino
(c) proton
(d) neutron

Answer

Answer: b

---

21. An element A decays into an element C by a two step process A → B+ ₂He⁴ and B → C + 2e^–. Then,
(a) A and C are isotopes
(b) A and C are isobars
(c) B and C are isotopes
(d) A and B are isobars

Answer

Answer: a

---

22. The equation 4₁ ¹H⁺ → 2⁴He²⁺ + 2e^– + 26 MeV
represents
(a) β-decay
(b) γ-decay
(c) fusion
(d) fission

Answer

Answer: c

---

23. Light energy emitted by star is due to
(a) breaking of nuclei
(b) joining of nuclei
(c) burning of nuclei
(d) reflection of solar light

Answer

Answer: b

---

24. In nuclear reaction, there is conservation of
(a) mass only
(b) energy only
(c) momentum only
(d) mass, energy and momentum

Answer

Answer: d

---

25. In nuclear reactors, the control rods are made of
(a) cadmium
(b) graphite
(c) krypton
(d) plutonium

Answer

Answer: a

---

26. Suppose we consider a large number of containers each containing initially 10000 atoms of a radioactive material with a half-life of 1 year. After 1 year, [NCERT Exemplar]
(a) all the containers will have 5000 atoms of the material.
(b) all the containers will contain the same number of atoms of the material but that number will only be approximately 5000.
(c) the containers will in general have different numbers of the atoms of the material but their average will be close to 5000.
(d) none of the containers can have more than 5000 atoms.

Answer

Answer:c

---

27. Jhe gravitational force between a H-atom and another particle of mass m will be given by Newton’s law: [NCERT Exemplar]

= magnitude of the potential energy of electron in the H-atom).

Answer

Answer: b

---

28. When a nucleus in an atom undergoes a radioactive decay, the electronic energy levels of the atom [NCERT Exemplar]
(a) do not change for any type of radioactivity.
(b) change for α and β radioactivity but not for γ-radioactivity.
(c) change for α-radioactivity but not for others.
(d) change for β-radioactivity but not for others.

Answer

Answer: b

---

29. M_x and M_y denote the atomic masses of the parent and the daughter nuclei respectively in a radioactive decay. The Q-value for a β^– decay is Q₁ and that for a β⁺ decay is Q₂ If m_e denotes the mass of an electron, then which of the following statements is correct? [NCERT Exemplar]

Answer

Answer: a

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30. Tritium is an isotope of hydrogen whose nucleus Triton contains 2 neutrons and 1 proton. Free neutrons decay into p + \(\bar{e}+\bar{v}\). If one of the neutrons in Triton decays, it would transform into He³ nucleus. This does not happen. This is because [NCERT Exemplar]
(a) Triton energy is less than that of a He³\ nucleus.
(b) the electron created in the beta decay process cannot remain in the nucleus.
(c) both the neutrons in triton have to decay simultaneously resulting in a nucleus with 3 protons, which is not a He³ nucleus.
(d) because free neutrons decay due to external perturbations which is absent in a triton nucleus.

Answer

Answer: a

---

31. Heavy stable nuclei have more neutrons than protons. This is because of the fact that [NCERT Exemplar]
(a) neutrons are heavier than protons.
(b) electrostatic force between protons are repulsive.
(c) neutrons decay into protons through beta decay.
(d) nuclear forces between neutrons are weaker than that between protons.

Answer

Answer: b

---

32. Samples of two radioactive nuclides A and B are taken λ_A and λ_B are the disintegration constants of A and B respectively. In which of the following cases, the two samples can simultaneously have the same decay rate at any time?
(a) Initial rate of decay of A is twice the » initial rate of decay of B and λ_A = λ_B.
(b) Initial rate of decay of A is less than the initial rate of decay of B and λ_A < λ_B.
(c) Initial rate of decay of B is twice the initial rate of decay of A and λ_A > λ_B.
(d) Initial rate of decay of B is same as the rate of decay of A at t = 2h and λ_B = λ_A.

Answer

Answer: d

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33. The variation of decay rate of two radioactive samples A and B with time is shown in figure. Which of the following statements are true?

(a) Decay constant of A is greater than that of B, hence A always decays faster than B.
(b) Decay constant of B is greater than that of A but its decay rate is always smaller than that of A.
(c) Decay constant of A is equal to that ofB.
(d) Decay constant of B is smaller than that of A but still its decay rate becomes equal to that of A at a later instant.

Answer

Answer: d

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34. Radioactivity is the phenomenon associated with
(a) decay of nucleus.
(b) production of radio waves.
(c) transmission of radio waves.
(d) reception of radio waves.

Answer

Answer: a

---

35. Which of the following are not emitted by radioactive substances?
(a) Electrons
(b) Protons
(c) Gamma rays
(d) Helium nuclei

Answer

Answer: b

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36. In an α-decay
(a) the parent and daughter nuclei have some number of protons.
(b) the daughter nucleus has one proton more than parent nucleus.
(c) the daughter nucleus has two protons less than parent nucleus.
(d) the daughter nucleus has two nucleus more than parent nucleus.

Answer

Answer: c

---

37. When a radioactive nucleus emits a (β-particle, the mass number of the atom:
(a) increases by one.
(b) remains the same.
(c) decreases by one.
(d) decreases by four.

Answer

Answer: b

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38. In a β-decay
(a) the parent and daughter nuclei have the same number of protons.
(b) the daughter nucleus has one proton less than parent nucleus.
(c) the daughter nucleus has one proton more than the parent nucleus.
(d) the daughter nucleus has one neutron more than the parent nucleus.

Answer

Answer: c

---

39. P-rays emitted by a radioactive material are
(a) electromagnetic radiations.
(b) electrons orbiting around the nucleus.
(c) neutral particles.
(d) charged particles emitted by nucleus.

Answer

Answer: d

---

40. During a mean life of a radioactive element the fraction that disintegrates is

Answer

Answer: c

---

41. γ-rays are originated from
(a) nucleus.
(b) outermost shell of nucleus.
(c) innermost shell of nucleus.
(d) outermost shell of atom.

Answer

Answer: a

---

42. Binding energy per nucleon of a stable nucleus is
(a) 8 eV
(b) 8 KeV
(c) 8 MeV
(d) 8 BeV

Answer

Answer: c

---

43. Sun’s radiant energy is due to
(a) nuclear fission.
(b) nuclear fusion.
(c) photoelectric effect.
(d) spontaneous radioactive decay.

Answer

Answer: b

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44. Average binding energy is maximum for
(a) C¹²
(b) Fe⁵⁶
(c) U²³⁵
(d) Po²¹⁰

Answer

Answer: b

---

45. A nucleus undergoes γ-decay due to
(a) excess of protons.
(b) excess of neutrons.
(c) large mass.
(d) its excited state.

Answer

Answer: d

---

46. The decay constant of a radioactive substance is X. Its half-life and mean life, respectively are

Answer

Answer: b

---

47. Neutrino is a particle, which is chargeless and has spin.

Answer/Explanation

Answer:
Explaination: ±\(\frac{1}{2}\)

---

48. Isotones have the same number of _________ .

Answer/Explanation

Answer:
Explaination: neutrons

---

49. Packing fraction of a nucleus is its _________ its per nucleon.

Answer/Explanation

Answer:
Explaination: mass defect

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50. How is the radius of a nucleus related to its mass number? [Panchkula 2019] [AI2011C]

Answer/Explanation

Answer:
Explaination:
The radius if of a nucleus of mass number A is related as if = R₀A^1/3, where R₀ is a constant.

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51. Two nuclei have mass numbers in the ratio 27 : 125. What is the ratio of their nuclear radii?

Answer/Explanation

Answer:
Explaination:

---

52. Two nuclei have mass numbers in the ratio 2 : 5. What is the ratio of their nuclear densities?

Answer/Explanation

Answer:
Explaination:
Nuclear density is independent of mass number. So, the ratio will be 1 : 1.

---

53. What is the relation between the binding energy per nucleon and stability of a nucleus?

Answer/Explanation

Answer:
Explaination:
The larger the binding energy per nucleon, the more stable is the nucleus.

---

54. Write any two characteristic properties of nuclear force. [Chennai-2019] [AI 2012,13]

Answer/Explanation

Answer:
Explaination:
The following are the two characteristic properties:
(i) Nuclear force is a short range force.
(ii) Nuclear forces show the saturation effect.

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55. How is the mean life of a radioactive sample related to its half-life? [Foreign 2011]

Answer/Explanation

Answer:
Explaination:

---

56. Define the activity of a given radioactive substance. Write its SI unit.

Answer/Explanation

Answer:
Explaination:
The rate of disintegration or count rate of sample of radioactive material is called activity. The SI unit of activity is becquerel (Bq).

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57. The radioactive isotope D decays according to the sequence

If the mass number and atomic number of D₂ are 176 and 71 respectively, what is
(i) the mass number
(ii) atomic number of D?

Answer/Explanation

Answer:
Explaination:

(i) Mass number of D = 180
(ii) Atomic number of D = 72

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58. A nucleus \(_{n} X^{m}\) emits one a-particle and one β-particle. What is the mass number and atomic number of the product nucleus?

Answer/Explanation

Answer:
Explaination:

Hence, the mass number of product is m – 4, and the atomic number of product is n – 1.

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59. In both β^– and β⁺ decay processes, the mass number of a nucleus remains same, whereas the atomic number Z increases by one in β^– decay and decreases by one in β⁺ decay. Explain, giving reason. [Foreign 2014]

Answer/Explanation

Answer:
Explaination:
In β^– decay, one neutron inside the nucleus decays into one proton and one electron (β^–). The proton remains inside the nucleus and the electron is ejected out.

In β⁺ decay, the conversion of proton into neutron and position (β⁺) takes place.

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60. Which nucleus has greater mean life, A or B?

Answer/Explanation

Answer:
Explaination:

Since, slope of A is more than slope of B.
Therefore, X is high and mean life e = \(\frac{1}{\lambda}\) for A is small.

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61. Why is a free neutron unstable but a free proton is a stable particle?

Answer/Explanation

Answer:
Explaination:
A free neutron is unstable outside the nucleus with an average life of 1000 s. It decays into a proton and emits a β^– particle, i.e.

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62. A neutron strikes a nucleus of \(_{5}^{\mathbf{10}} \mathbf{B}\) and emits an alpha particle. Write down the nuclear reaction for it.

Answer/Explanation

Answer:
Explaination:

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63. Write the necessary condition required for fusion reaction.

Answer/Explanation

Answer:
Explaination:
(i) Nuclear fusion will occur when the kinetic energy of colliding nuclei is enough to overcome the strong electrostatic forces of repulsion between the protons. For this, high temperature is required.
(ii) The density of nuclei should also be very high to increase the number of collisions.

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64. Out of \(_{14}^{30} X ;_{3}^{6} Y \text { and }_{40} Z^{130}\), which is more likely to undergo the nuclear fusion?

Answer/Explanation

Answer:
Explaination:
A lighter unstable nucleus \(_{3}^{\mathbf{6}} \mathbf{Y}\) can undergo the nuclear fusion.

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65. What is the effect of temperature on radioactivity?

Answer/Explanation

Answer:
Explaination:
No effect. Radioactivity is independent of temperature.

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66. What is the difference between an electron and a β-particle?

Answer/Explanation

Answer:
Explaination:
An electron resides outside the nucleus, whereas β-particle is an electron like particle of nuclear origin.

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67. What is the source of stellar energy?

Answer/Explanation

Answer:
Explaination: Nuclear fusion reactions.

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68. Four nuclei of an element fuse together to form a heavier nucleus. If the process is accompanied by the release of energy, which of the two—the parent or the daughter nucleus would have a higher binding energy/ nucleons? [CBSE 2018]

Answer/Explanation

Answer:
Explaination: Daughter nucleus.

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69. You are given two nuelei \(_{3}^{7} X \text { and }_{3}^{4} Y\), which one of the two is likely to be more stable? Give reason.

Answer/Explanation

Answer:
Explaination: \(_{3}^{\mathbf{7}} \mathbf{X}\) is more stable, as it contains more neutrons than protons.

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70. The \(_{10}^{\mathbf{23}} \mathbf{Ne}\) decays by β^– emission into \(_{11}^{\mathbf{23}} \mathbf{Na}\). Write down the β^– decay equation.

Answer/Explanation

Answer:
Explaination:

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Free PDF Download of CBSE Physics Multiple Choice Questions for Class 12 with Answers Chapter 12 Atoms. Physics MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Physics Atoms MCQs Pdf with Answers to know their preparation level.

Atoms Class 12 Physics MCQs Pdf

1. If 13.6 eV energy is required to ionise the hydrogen atom, then energy required to remove an electron from n = 2 is
(a) 10.2 eV
(b) 0 eV
(c) 3.4 eV
(d) 6.8 eV.

Answer/Explanation

Answer: c
Explaination:

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2. In Bohr’s model of an atom which of the following is an integral multiple of \(\frac{h}{2 \pi}\)?
(a) Kinetic energy
(b) Radius of an atom
(c) Potential energy
(d) Angular momentum

Answer/Explanation

Answer:
Explaination:
(d) Angular momentum L = mvr = \(\frac{n h}{2 \pi}\)

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3. In Bohr’s model, the atomic radius of the first orbit is rQ. Then, the radius of the third orbit is
(a) r₀/9
(b) r₀
(c) 9r₀
(d) 3r₀

Answer/Explanation

Answer: c
Explaination:
r_n = r_nn²
∴ r₃ = 9r₀

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4. The K.E. of the electron in an orbit of radius r in hydrogen atom is proportional to

Answer/Explanation

Answer: b
Explaination:
(b) \(\frac{e^{2}}{2 r}\), Scince K.E = \(\frac{k e^{2}}{2 r}\)

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5. The ratio between Bohr radii is
(a) 1 : 2 : 3
(b) 2 : 4 : 6
(c) 1 : 4 : 9
(d) 1 : 3 : 5

Answer/Explanation

Answer: c
Explaination:
(c) 1 : 4 : 9, In Bohr’s atomic model, r_n n²

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6. The longest wavelength in Balmer series of hydrogen spectrum will be
(a) 6557 Å
(b) 1216 Å
(c) 4800 Å
(d) 5600 Å

Answer/Explanation

Answer: a
Explaination:
(a) 6557 Å
For longest wavelength in Balmer series n₁ = 2 and n₂ = 3

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7. In terms of Rydberg constant R, the wave number of the first Balmer line is
(a) R
(b) 3R
(c) \(\frac{5 R}{36}\)
(d) \(\frac{8 R}{9}\)

Answer/Explanation

Answer: c
Explaination:

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8. The ionisation energy of hydrogen atom is 13.6 eV. Following Bohr’s theory the energy corresponding to a transition between 3rd and 4th orbits is
(a) 3.40 eV
(b) 1.51 eV
(c) 0.85 eV
(d) 0.66 eV

Answer/Explanation

Answer: d
Explaination:

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9. The energy of hydrogen atom in the nth orbit is En, then the energy in the nth orbit of single ionised helium atom is

Answer/Explanation

Answer: c
Explaination:
(c) As energy E ∝ Z²
For hydrogen atom Z = 1,
for Helium Z = 2
E_He = 4E_n.

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10. On moving up in the energy states of a H-like atom, the energy difference between two consecutive energy states
(a) decreases.
(b) increases.
(c) first decreases then increases.
(d) first increases then decreases.

Answer/Explanation

Answer: a
Explaination:
(a) As, E_n = \(\frac{-13.6}{n^{2}}\)

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11. The transition of electron from n = 4, 5, 6, ………. to n = 3 corresponds to
(a) Lyman series
(b) Balmer series
(c) Paschen series
(d) Brackettseries

Answer/Explanation

Answer: c
Explaination:
(c) In transition from n₁ = 3 and n₂ = 4, 5, 6,….
Infrared radiation of Paschen spectral is emitted.

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12. As per Bohr model, the minimum energy (in eV) required to remove an electron from the ground state of double ionized Li atom (Z = 3) is
(a) 1.51 eV
(b) 13.6 eV
(c) 40.8 eV
(d) 122.4 eV

Answer/Explanation

Answer: d
Explaination:
(d) Since energy of electron in nth state of hydrogen like atom is

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13. Which of the following spectral series in hydrogen atom gives spectral line of 4860 A?
(a) Lyman
(b) Balmer
(c) Paschen
(d) Brackett

Answer/Explanation

Answer: b
Explaination:
(b) Since spectral line of wavelength 4860 A
lies in the visible region of the spectrum which is Balmer series of the spectrum.

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14. In terms of Rydberg constant R, the shortest wavelength in Balmer series of hydrogen atom spectrum will have wavelength

Answer/Explanation

Answer: b
Explaination:
(b) For shortest wavelength n₁ =∞, n₂ = 2

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15. The first model of atom in 1898 was proposed by
(a) Ernst Rutherford
(b) Albert Einstein
(c) J.J. Thomson
(d) Niels Bohr

Answer

Answer: c

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16. In Geiger-Marsden scattering experiment, the trajectory traced by an a-particle depends on
(a) number of collision
(b) number of scattered a-particles
(c) impact parameter
(d) none of these

Answer

Answer: c

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17. In the Geiger-Marsden scattering experiment the number of scattered particles detected are maximum and minimum at the scattering angles respectively at
(a) 0° and 180°
(b) 180° and 0°
(c) 90° and 180°
(d) 45° and 90°

Answer

Answer: a

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18. In the Geiger-Marsden scattering experiment, is case of head-on collision the impact parameter should be
(a) maximum
(b) minimum
(c) infinite
(d) zero

Answer

Answer: a

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19. Rutherford’s experiments suggested that the size of the nucleus is about
(a) 10^-14 m to 10^-12 m
(b) 10^-15 m to 10^-13 m
(c) 10^-15 m to 10^-14 m
(d) 10^-15 m to 10^-12 m

Answer

Answer: c

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20. Which of the following spectral series falls within the visible range of electromagnetic radiation?
(a) Lyman series
(b) Balmer series
(c) Paschen seriee
(d) Pfund series

Answer

Answer: b

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21. The first spectral series was discovered by
(a) Balmer
(b) Lyman
(c) Paschen
(d) Pfund

Answer

Answer: a

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22. Which of the following postulates of the Bohr model led to the quantization of energy of the hydrogen atom?
(a) The electron goes around the nucleus in circular orbits.
(b) The angular momentum of the electron can only be an integral multiple of h/2π.
(c) The magnitude of the linear momentum of the electron is quantized.
(d) Quantization of energy is itself a postulate of the Bohr model.

Answer

Answer: b

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23. The Bohr model of atoms
(a) assumes that the angular momentum of elec-trons is quantized.
(b) uses Einstein’s photoelectric equation.
(c) predicts continuous emission spectra for at-oms.
(d) predicts the same emission spectra for all types of atoms.

Answer

Answer: a

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24. If tt is the orbit number of the electron in a hydrogen atom, the correct statement among the following is
(a) electron energy increases as n increases.
(b) hydrogen emits infrared rays for the electron transition from n = to n = 1
(c) electron energy is zero for n = 1 (<0 electron energy varies as n2.

Answer

Answer: a

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25. If the radius of inner most electronic orbit of a hydrogen atom is 5.3 * 10~n m, then the radii of n = 2 orbits is
(a) 1.12 Å
(b) 2.12 Å
(c) 3.22 Å
(d) 4.54 Å

Answer

Answer: b

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26. The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

(a) I
(b) II
(c) III
(d) IV

Answer

Answer: c

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27. In a hydrogen atom, the radius of n^th Bohr orbit is r_n. The graph between log(r_n/r₁) and log n will be

Answer

Answer: a

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28. The transition from the state n = 5 to n = 1 in a hydrogen atom results in UV radiation. Infrared radiation will be obtained in the transition
(a) 2 → 1
(b) 3 → 2
(c) 4 → 3
(d) 6 → 2

Answer

Answer: c

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29. The hydrogen atom can give spectral lines in the Lyman, Balmer and Paschen series. Which of the following statement is correct?
(a) Lyman series is in the infrared region.
(b) Balmer series is in the visible region.
(c) Paschen series is in the visible region.
(d) Balmer series is in the ultraviolet region.

Answer

Answer: b

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30. Which of the relation is correct between time period and number of orbits while an electron is resolving in an orbit?

Answer

Answer: c

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31. Energy of an electron in the second orbit of hydrogen atom is E and the energy of electron in 3rd orbit of He will be

Answer/Explanation

Answer: b
Explaination:

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32. The spectral lines in the Brackett series arise due to transition of electron in hydrogen atom from higher orbits to the orbit with
(a) n = 1
(b) n = 2
(c) n = 3
(d) n = 4

Answer

Answer: d

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33. Taking the Bohr radius as a0 = 53 pm, the radius of Li++ ion in its ground state, on the basis of Bohr’s model, will be about [NCERT Exemplar]
(a) 53 pm
(b) 27 pm
(c) 18 pm
(d) 13 pm

Answer

Answer: c

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34. The simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons. This is because [NCERT Exemplar]
(a) of the electrons not being subject to a central force.
(b) of the electrons colliding with each other.
(c) of screening effects.
(d) the force between the nucleus and an electron will no longer be given by Coulomb’s law.

Answer

Answer: a

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35. For the ground state, the electron in the H-atom has an angular momentum = h, according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true, [NCERT Exemplar]
(a) because Bohr model gives incorrect values of angular momentum.
(b) because only one of these would have a minimum energy.
(c) angular momentum must be in the direction of spin of electron.
(d) because electrons go around only in horizontal orbits.

Answer

Answer: a

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36. 02 molecule consists of two oxygen atoms. In the molecule, nuclear force between the nuclei of the two atoms [NCERT Exemplar]
(a) is not important because nuclear forces are short-ranged.
(b) is as important as electrostatic force for binding the two atoms.
(c) cancels the repulsive electrostatic force between the nuclei.
(d) is not important because oxygen nucleus has equal number of neutrons and protons.

Answer

Answer: a

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37. Two H atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced is [NCERT Exemplar]
(a) 10.20 eV
(b) 20.40 eV
(c) 13.6 eV
(d) 27.2 eV

Answer

Answer: a

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38. A set of atoms in an excited state decays. [NCERT Exemplar]
(a) in general to any of the states with lower energy.
(b) into a lower state only when excited by an external electric field.
(c) all together simultaneously into a lower state.
(d) to emit photons only when they collide.

Answer

Answer: a

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39. An ionised H-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state, [NCERT Exemplar]
(a) the electron would move in circular orbits.
(b) the energy would be (2)⁴ times that of a H-atom.
(c) the electrons, orbit would go around the protons.
(d) the molecule will soon decay in a proton and a H-atom.

Answer

Answer: c

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40. The Balmer series for the H-atom can be observed
(a) if we measure the frequencies of light emitted when an excited atom falls to the ground state.
(b) if we measure the frequencies of light emitted due to transitions between excited states and the first excited state.
(c) in any transition in a H-atom.
(d) as a sequence of frequencies with the lower frequencies getting closely packed.

Answer

Answer: b

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41. Let \(E_{n}=\frac{-1}{8 \varepsilon_{0}^{2}} \frac{m e^{4}}{n^{2} h^{2}}\) be the energy of the nth level of H-atom. If all the H-atoms are in the ground state and radiation of frequency (E₂ – E₁)/h falls on it,
(a) it will not be absorbed at all.
(b) some of atoms will move to the first excited state.
(c) all atoms will be excited to the n = 2 state.
(d) all atoms will make a transition to the n = 3 state.

Answer

Answer: d

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42. The Bohr model of an atom
(a) assumes that the angular momentum of electrons is quantised.
(b) uses Einstein’s potoelectric equation.
(c) predicts continuous emission spectra for atoms,
(d) predicts the same emission spectra for all types of atoms.

Answer

Answer: a

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43. For ionising an exicited hydrogan atom, the energy required (in eV) will be
(a) a little less than 13.6 eV
(b) 13.6 eV
(c) more than 13.6 eV
(d) 3.4 or less

Answer/Explanation

Answer: d
Explaination:
(d) As the energy of the electron is – -3.4 eV in first excited state and magnitude is less for higher excited state.

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44. The electrons in the Bohr’s orbit have
(a) K.E. greater than P.E.
(b) P.E. greater than K.E.
(c) the same values
(d) none of these

Answer/Explanation

Answer: a
Explaination:

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45. The binding energy of a H-atom, considering an electron moving around a fixed nuclei (proton), is
\(B=-\frac{m e^{4}}{8 n^{2} \varepsilon_{0}^{2} h^{2}}\). (m = electron mass)
If one decides to work in a frame of reference where the electron is at rest, the proton would be moving arround it. By similar arguments, the binding energy would be
\(B=-\frac{M e^{4}}{8 n^{2} \varepsilon_{0}^{2} h^{2}}\)(M= proton mass)
This last expression is not correct because [NCERT Exemplar]
(a) n would not be integral.
(b) Bohr-quantisation applies only to electron.
(c) the frame in which the electron is at rest is not inertial.
(d) the motion of the proton would not be in circular orbits, even approximately.

Answer

Answer: c

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46. Consider aiming a beam of free electrons towards free protons. When they scatter, an electron and a proton cannot combine to produce a H-atom,
(a) because of energy loss.
(b) without simultaneously releasing energy in the from of radiation.
(c) because of momentum conservation.
(d) because of angular momentum conservation.

Answer

Answer: b

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47. The Bohr model for the spectra of a H-atom
(a) will be applicable to hydrogen in the molecular from.
(b) will not be applicable as it is for a He- atom.
(c) is valid only at room temperature.
(d) predicts continuous as well as discrete spectral lines.

Answer

Answer: b

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48. Non-radiating electron orbits in an atom are called __________ orbits.

Answer/Explanation

Answer:
Explaination: stationary

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49. At distance of closest approach, kinetic energy of a-particle is __________ .

Answer/Explanation

Answer:
Explaination: zero

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50. The centripetal force required for revolution of electron in an orbit is provided by __________ between the electron and the nucleus.

Answer/Explanation

Answer:
Explaination: electrostatic attraction

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51. __________ is the perpendicular distance of the velocity vector of the a-particle from the centre of the nucleus.

Answer/Explanation

Answer:
Explaination: Impact parameter

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52. The number of waves, contained in unit length of the medium is called __________ .

Answer/Explanation

Answer:
Explaination: wave number

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53. Angular momentum and energy of an electron in an atom is __________ .

Answer/Explanation

Answer:
Explaination: quantised.

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54. Number of possible spectral lines emitted on dexcitation of electron from energy level n to ground state is equal to __________ .

Answer/Explanation

Answer:
Explaination: \(\frac{n(n-1)}{2}\)

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55. In the Rutherford scattering experiment, die distance of closest approach for an a-particle is dQ. If an a-particle is replaced by a proton, how much kinetic energy in comparison to a-particle will it require to have the same distance of closest approach d₀?

Answer/Explanation

Answer:
Explaination:
At distance of closest approach, the K.E. with the charged particle is converted into electrostatic P.E.
As q is half with a proton in comparison to a-particle, for same d, energy E has to be made half.

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56. What is the ratio of radii of the orbits corresponding to first excited state and ground state in a hydrogen atom?

Answer/Explanation

Answer:
Explaination:

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57. Write the expression for Bohr’s radius in hydrogen atom.

Answer/Explanation

Answer:
Explaination:
Bohr’s radius in hydrogen atom,

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58. Find the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its
(i) second permitted energy level to the first level, and
(ii) the highest permitted energy level to the first permitted level.

Answer/Explanation

Answer:
Explaination:

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59. What is the distance of closest approach?

Answer/Explanation

Answer:
Explaination:
The minimum distance up to which an energetic a-particle travelling directly towards a nucleus can reach.

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60. An electron in a hydrogen atom is revolving round a positively charged nucleus. Which two physical quantities explain the orbit of an electron?

Answer/Explanation

Answer:
Explaination:
Two physical quantities are:
(i) angular momentum, and
(ii) total energy of electron.

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61. What will happen if an electron instead of revolving becomes stationary in H-atom?

Answer/Explanation

Answer:
Explaination:
Then the electrostatic field of the nucleus will attract the electron into the nucleus itself.

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62. Calculate the speed of electron revolving around the nucleus of a hydrogen atom in order that it may not be pulled into the nucleus by electrostatic attraction.

Answer/Explanation

Answer:
Explaination:
It is only possible when the centripetal force is equal to electrostatic force of attraction.

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63. What is the value of ionization energy for a hydrogen atom?

Answer/Explanation

Answer:
Explaination: 13.6

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