NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current

NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 14
Chapter Name Chemical Effects of Electric Current
Number of Questions Solved 12
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current

NCERT TEXTBOOK EXERCISES

Question 1.
Fill in the blanks:

  1. Most liquids that conduct electricity are solutions of……..,……………and …………..
  2. The passage of an electric current through a solution causes…………..effects.
  3. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the………..terminal of the battery.
  4. The process of depositing a layer of any desired metal on another material by means of electricity is called.………

Answer.

  1. acids, bases, salts
  2. chemical
  3. negative
  4. electroplating.

Question 2.
When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
Answer.
Yes, it is because the solution conducts electricity.

Question 3.
Name three liquids, which when tested in the manner shown in Fig. 14.1, may cause the magnetic needle to deflect.
NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current 1
Answer.
Tap water/sodium chloride solution, hydrochloric acid.

Question 4.
The bulb does not glow in the setup shown in Fig. 14.2. List the possible reasons. Explain your answer.
Answer.
List of possible reasons:

  1. The liquid solution might be conducting electricity, but the current produced is too small so that the filament of the bulb does not get heated and the bulb does not glow.
  2. Or, it is possible that the connections are loose.
  3. Or, the bulb is fused.
  4. Or, the cells are used up.
    NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current 2

Question 5.
A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that
(i) liquid A is a better conductor than liquid B.
(ii) liquid B is a better conductor than liquid A.
(iii) both liquids are equally conducting.
(iv) conducting properties of liquid cannot be compared in this manner.
Answer.
If the bulb glows brightly with liquid A, it means that liquid A is a better conductor of electricity than B. So the answer will be (i).

Question 6.
Does pure water conduct electricity? If not, what can we do to make it conducting?
Answer.
Pure water does not conduct electricity. It can be made conducting if acid, base, or salt is dissolved in it.

Question 7.
In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply of the area. Explain why they do this.
Answer.
The water used in water hoses is not pure water and it conducts electricity. Firemen shut off the main electrical supply of the area because if the supply of electricity continues there may be a high risk of electrocution in the whole area due to water.

Question 8.
A child staying in a coastal region test the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
Answer.
The impure water is the conductor of electricity. Seawater contains more impurity (salt) than drinking water. Therefore, seawater conducts more electricity than drinking water. That is why the compass needle deflects more in the case of seawater.

Question 9.
Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpours? Explain.
Answer.
It is not safe for the wireman to carry out electrical repairs outside during heavy downpours. Because during heavy downpour there is a high risk of electrocution.

Question 10.
Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise, she found that the compass needle showed deflection. What could be the reasons?
Answer.
Rainwater is, of course, as good as distilled water but, when it passes through the atmosphere, it dissolves a lot of dust, dirt, and impurities and becomes conductive. So, when Paheli used a tester, its compass showed deflection.

Question 11.
Prepare a list of objects around you that are electroplated.
Answer.
Ornaments, wheel rims of vehicles, the handlebar of cycle and motorcycle, pots of one metal coated with other, bath taps, kitchen gas burner, the bottom of cooking utensils, handles of doors, tin cans, etc.

Question 12.
The process that you saw in Activity 14.7 (NCERT) is used for the purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?
Answer.
To perform such activity we have to arrange copper sulphate crystals and two copper plates each having a size around 10 cm long and 4 cm wide. Now take 250 mL distilled water in a clean and dry beaker. Dissolve two teaspoonfuls of copper sulphate crystals in it to obtain copper sulphate solution. (You may add few drops of dilute sulphuric acid to copper sulphate solution to make it more conducting). Clean each copper plate with sandpaper. Now rinse it with water. With the help of wires, connect one copper plate to each terminal of two cell batteries (Take care that the two plates do not touch each other).
NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current 3
Immerse two plates in copper sulphate solution as shown in Fig. 14.3. Allow the current to pass through for 5 to 7 minutes.

When an electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. The free copper gets drawn to the plate connected to the negative terminal of the battery and thus gets deposited on that plate. Gradually, a layer of copper builds upon the plate.

We hope the NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 14 Chemical Effects of Electric Current, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 13 Sound

NCERT Solutions for Class 8 Science Chapter 13 Sound are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 13 Sound.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 13
Chapter Name Sound
Number of Questions Solved 13
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 13 Sound

NCERT TEXTBOOK EXERCISES

Question 1.
Choose the correct answer:
Sound can travel through
(a) gases only
(b) solids only
(c) liquids only
(d) solids, liquids and gases
Answer.
(d) solids, liquids and gases.

Question 2.
Voice of which of the following is likely to have minimum frequency?
(a) Baby girl
(b) Baby boy
(c) A man
(d) A woman
Answer.
(b) Baby boy.

Question 3.
In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false:

  1. Sound cannot travel in a vacuum. (T/F)
  2. The number of oscillations per second of a vibrating object is called its time period. (T/F)
  3. If the amplitude of vibration is large, the sound is feeble. (T/F)
  4. For human ears, the audible range is 20 Hz to 20,000 Hz. (T/F)
  5. The lower the frequency of vibration, the higher is the pitch. (T/F)
  6. Unwanted or unpleasant sound is termed music. (T/F)
  7. Noise pollution may cause partial hearing impairment. (T/F)

Answer.

  1. True
  2. False
  3. False
  4. True
  5. False
  6. False
  7. True

Question 4.
Fill in the blanks with suitable words:

  1. Time taken by an object to complete one oscillation is called…….
  2. Loudness is determined by the………..of vibration.
  3. The unit of frequency is………….
  4. Unwanted sound is called……….
  5. The shrillness of a sound is determined by the.……….of vibration.

Answer.

  1. time period
  2. amplitude
  3. Hertz (Hz)
  4. noise
  5. frequency.

Question 5.
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Answer.
NCERT Solutions for Class 8 Science Chapter 13 Sound 1

Question 6.
The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?
Answer.
Number of vibrations per second = 500
Time period = time is taken for one vibration
NCERT Solutions for Class 8 Science Chapter 13 Sound 2

Question 7.
Identify the part which vibrates to produce sound in the following instruments:

  1. Dholak
  2. Sitar
  3. Flute

Answer.

  1. Stretched membrane
  2. String of sitar
  3. Air column.

Question 8.
What is the difference between noise and music? Can music become noise sometimes?
Answer.
The unpleasant sound is called noise, whereas a pleasant sound is called music. Noise can produce so many health hazards, whereas music brings about a soothing effect. Yes, music can become noise sometimes when the musical instruments produce very high volume sounds.

Question 9.
List sources of noise pollution in your surroundings.
Answer.
Following are the major sources of noise pollution:

  1. Sounds of vehicles.
  2. Sounds of the bursting of crackers and explosives.
  3. Sounds of loudspeakers, TVs, transistors.
  4. Sounds of kitchen appliances.
  5. Sounds of desert coolers, air conditioners etc.

Question 10.
Explain in what way noise pollution is harmful to humans.
Answer.
Noise pollution may cause many health-related problems.

  • Lack of sleep, hypertension (high blood pressure), anxiety, etc. are some of the problems that may be caused due to noise pollution.
  • A person who is exposed to a loud sound continuously may get temporary or even permanent deafness.

Question 11.
Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.
Answer.
I would suggest my parents buy the house which is three lanes away from the roadside. This would protect us from noise pollution which is maximum on the roadside.

Question 12.
Sketch the larynx and explain its function in your own words.
Answer.
In humans, the sound is produced by the voice box or the larynx. It is situated in the throat. Below it is the windpipe. The two vocal cords are stretched across the voice box or larynx in such a way that it leaves a narrow slit between them for the passage of air when the lungs force air through the slit, the vocal cords vibrate and the vibration results in sound.
NCERT Solutions for Class 8 Science Chapter 13 Sound 3

Question 13.
Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain why?
Answer.
The light travels at the speed of 3 x 10s ms-1, which is very large in comparison to the speed of sound which travels at the rate of 330 ms-1 in the air. That is why lightning is seen earlier and thunder is heard later.

We hope the NCERT Solutions for Class 8 Science Chapter 13 Sound helps you. If you have any query regarding NCERT Solutions for Class 8 Science 13 Sound, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 12 Friction

NCERT Solutions for Class 8 Science Chapter 12 Friction are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 12 Friction.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 12
Chapter Name Friction
Number of Questions Solved 10
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 12 Friction

NCERT TEXTBOOK EXERCISES

Question 1.
Fill in the blanks:

  1. Friction opposes the…………….between the surfaces in contact with each other.
  2. Friction depends on the.…………..of surfaces.
  3. Friction produces ……………….
  4. A sprinkling of powder on the carrom board.…………….friction.
  5. Sliding friction is……….than the static friction.

Answer.

  1. relative motion
  2. smoothness (or irregularities or nature)
  3. heat
  4. reduces
  5. less.

Question 2.
Four children were asked to arrange forces due to rolling, static, and sliding frictions in decreasing order. Their arrangements are given below. Choose the correct arrangement.
(a) rolling, static, sliding
(b) rolling, sliding, static
(c) static, sliding, rolling
(d) sliding, static, rolling
Answer.
(c) static, sliding, rolling.

Question 3.
Alida runs her toy car on the dry marble floor, wet marble floor, newspaper, and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be
(a) wet marble floor, dry marble floor, newspaper, and towel,
(b) newspaper, towel, dry marble floor, wet marble floor,
(c) towel, newspaper, dry marble floor, wet marble floor,
(d) wet marble floor, dry marble floor, towel, newspaper.
Answer.
(a) wet marble floor, dry marble floor, newspaper, and towel.

Question 4.
Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
Answer.
The frictional force will act parallel to the inclined surface, opposite to the direction of the sliding of the book.

Question 5.
You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?
Answer.
It is difficult to walk on a soapy floor because a soapy floor applies very little friction and hence we can slip on such floors.

Question 6.
Explain why sportsmen use shoes with spikes.
Answer.
Sportsmen use shoes with spikes because spikes produce the desired frictional force and thus help in holding the ground firmly.

Question 7.
Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Answer.
We know that the force of friction is increased if the two surfaces are pressed harder. A heavier box will apply more pressure on the floor and hence Seema will experience more frictional force.

Question 8.
Explain why sliding friction is less than static friction.
Answer.
Friction is caused by the interlocking of irregularities in the two surfaces. When the object starts sliding, the contact points on its surface, do not get enough time to lock into the contact points of the other surface. So, the sliding friction is slightly smaller than the static friction.

Question 9.
Give examples to show that friction is both a friend and a foe.
Answer.

Friction is both friend and foe, that is why it is said that friction is a necessary evil.

1. Friction as a friend:

  • To hold a glass, we have ridges on our palm, which increase the friction between palm and glass.
  • We are able to write anything with a pen or pencil because there is friction between the surfaces of paper and the point of a pen (nib) or pencil.
  • A teacher can write on the blackboard with chalk because of the friction between the black-board surface and the chalk.
  • If there is no friction, then a moving body would never stop.
  • A nail could not be fixed in the wall, or a knot could not Be tied, had there been any friction.
  • No building could be constructed without friction.

2. Friction as a foe:

  • Friction wears out materials, whether they are screws, ball-bearings, or soles of shoes.
  • Friction can also produce heat, which increases the wear and tear of machine parts. It also causes much wastage of energy, because this heat is not utilized.

Question 10.
Explain why objects moving in fluids must have special shapes.
Answer.
Birds and the fishes have to move about in fluids all the time. Thus, their “bodies have evolved to shapes which make them not to lose much energy in overcoming fluid friction. Such shapes are called streamlined. Cars are also designed so that their shapes resemble the streamlined shapes of birds, fishes, etc.

We hope the NCERT Solutions for Class 8 Science Chapter 12 Friction help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 12 Friction, drop a comment below and we will get back to you at the earliest.

Online Education NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3

In Online Education NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 are part of NCERT Solutions for Class 8 Maths. Here we have given NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3.

Board CBSE
Textbook NCERT
Class Class 8
Subject Maths
Chapter Chapter 11
Chapter Name Mensuration
Exercise Ex 11.3
Number of Questions Solved 10
Category NCERT Solutions

Online Education NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3

Question 1.
There are two cuboidal boxes as shown in the adjoining figure. Which box requires the lesser amount of material to make?
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 1
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 2

Question 2.
A suitcase with measures 80 cm x 48 cm x 24 cm is to be covered with a tarpau¬lin cloth. How many meters of tarpaulin of width 96 cm is required to cover 100 such suitcases?
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 3

Question 3.
Find the side of a cube whose surface area is 600 \({ cm }^{ 2 }\).
Solution.
Let the side of the cube be a cm.
Then, Total surface area of the cube = 6\({ a }^{ 2 }\)
According to the question,
6\({ a }^{ 2 }\)= 600
⇒ \({ a }^{ 2 }\) = \(\frac { 600 }{ 6 } \)
⇒ \({ a }^{ 2 }\) = 100
⇒ a = \(\sqrt { 100 } \)
⇒ a = 10 cm
Hence, the side of the cube is 10 cm.

Question 4.
Rukhsar painted the outside of the cabinet of measure 1 m x 2 m x 1.5 m. How much surface area did she cover if she painted all except the bottom of the cabinet?
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 4
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 5

Question 5.
Daniel is painting the walls and ceiling of a cuboidal hall with length, breadth, and height of 15 m, 10 m and 7 m respectively. From each can of paint 100 \({ m }^{ 2 }\) of area is painted.
How many cans of paint will she need to paint the room?
Solution.
l = 15 m
b = 10 m
h = 7 m
Surface area to be painted
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 6
Hence, she will need 5 cans of paint to paint the room.

Question 6.
Describe how the two figures at the right are alike and how they are different. Which box has a larger lateral surface area?
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 7
Solution.
Similarity → Both have the same heights.
Difference → One is a cylinder, the other is a cube;
The cylinder is a solid obtained by revolving a rectangular area about its one side whereas a cube is a solid enclosed by six square faces; a cylinder has two circular faces whereas a cube has six square faces.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 8

Question 7.
A closed cylindrical tank of radius 7 m and height 3 m is made from a sheet of metal. How many sheets of metal is required?
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 9
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 10

Question 8.
The lateral surface area of a hollow cylinder is 4224 \({ cm }^{ 2 }\). It is cut along its height and formed a rectangular sheet of width 33 cm. Find the perimeter of rectangular sheet?
Solution.
Lateral surface area of the hollow cylinder = 4224 \({ cm }^{ 2 }\)
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 11

Question 9.
A road roller takes 750 complete revolutions to move once over to level a road. Find the area of the road if the diameter of a road roller is 84 cm and length is 1 m.
Solution.
Diameter of the road roller = 84 cm
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 12
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 13

Question 10.
A company packages its milk powder in the cylindrical container whose base has a diameter of 14 cm and height 20 cm. The company places a label around the surface of the container (as shown in the figure). If the label is placed 2 cm from top and bottom, what is the area of the label?
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 14
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 15

 

We hope the NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3 help you. If you have any query regarding NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.3, drop a comment below and we will get back to you at the earliest.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Here we are providing Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory was designed by subject expert teachers. https://ncertmcq.com/class-8-history-chapter-2-extra-questions/

From Trade to Territory Class 8 Extra Questions History Chapter 2

Question 1.
Who was the last powerful Mughal ruler?
Answer:
Aurangzeb.

Question 2.
How did the Mughal empire become weak?
Answer:
After Aurangzeb’s death, many Mughal governors began establishing their own regional kingdoms. This weakened Mughal empire.

Question 3.
When and where was the East India Company established?
Answer:
The East India Company was established in 1600, in England.

Question 4.
Who gave a Charter to the Company to trade with the East?
Answer:
Queen Elizabeth I.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 5.
What did the Charter mean?
Answer:
The Charter meant that no other trading group in England could compete with the East India Company.

Question 6.
Which western power came first to India?
Answer:
Portuguese.

Question 7.
Who discovered the sea route to India and when?
Answer:
Portuguese explorer Vasco da Gama discovered the sea route to India in 1498.

Question 8.
Where was the Portuguese base in India?
Answer:
In India, the Portuguese base was in Goa.

Question 9.
Through which route the British came to India?
Answer:
The British came to India through the Cape of Good Hope (South of Africa).

Question 10.
Name the two European powers other than British and Portuguese who established trade links with India.
Answer:
Dutch and French.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 11.
What were the major trade items for the European powers?
Answer:
Cotton and silk textiles – pepper, cloves, cardamom, cinnamon, etc.

Question 12.
When and where was the first English factory set up?
Answer:
The first English factory was set up in 1651 on the bank of the river Hugli.

Question 13.
What were the Company’s traders known as?
Answer:
The Company’s traders were known as ‘factors’.

Question 14.
Which Mughal Emperor granted the Company the right to trade duty-free through farman?
Answer:
Aurangzeb, through his Farman, granted the right to the Company to trade duly free.

Question 15.
Name the Nawabs of Bengal who asserted their power and autonomy against the Mughals.
Answer:

  • Murshid Quli Khan
  • Alivardi Khan
  • Sirajuddaulah.

Question 16.
Who were the two sides in the Battle of Plassey?
Answer:
The two sides in the Battle of Plassey were the Nawab of Bengal and the East India Company.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 17.
Which Nawab of Bengal was defeated in the Battle of Plassey?
Answer:
Sirajuddaulah.

Question 18.
Who led the Company in the Battle of Plassey?
Answer:
Robert Clive.

Question 19.
Why did the Battle of Plassey become famous?
Answer:
The Battle of Plassey became famous because it was the first major victory, the Company won in India.

Question 20.
Name the Commander who decided Siraj Abdallah in the Battle of Plassey.
Answer:
Mir Jafar.

Question 21.
Why was Mir Jafar deposed by the Company? Who was made the new Nawab?
Answer:
Mir Jafar was deposed by the Company because he was unwilling to do as per the Company’s directions. Mir Qasim was made the new Nawab.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 22.
Which Nawab was defeated in the Battle of Buxar?
Answer:
Mir Qasim.

Question 23.
When was the Battle of Buxar fought?
Answer:
In 1764.

Question 24.
Who made Company the Diwan of the provinces of Bengal and when?
Answer:
The Mughal Emperor, in 1765.

Question 25.
What did Diwani to the Company mean?
Answer:
Diwani allowed the Company to use the vast revenue resources of Bengal.

Question 26.
Why was Robert Clive cross-examined by the British Parliament?
Answer:
Robert Clive was cross-examined by the British Parliament on the charges of corruption and amassing huge wealth in India during his service period.

Question 27.
What was the role of Residents appointed by the Company in the Indian states?
Answer:
Through the Residents, the Company tried to interfere in the internal affairs of Indian states.

Question 28.
Name any two Indian states which fell victim to the subsidiary alliance.
Answer:
Awadh and Hyderabad.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 29.
Who was Hyder Ali?
Answer:
Hyder Ali was the ruler of the state of Mysore.

Question 30.
Which foreign power helped Tipu modernise his army?
Answer:
The French helped Tipu modernise his army.

Question 31.
How many wars were fought between the state of Mysore and the British?
Answer:
Four.

Question 32.
In which battle was Tipu Sultan killed?
Answer:
Tipu Sultan was killed in the Battle of Seringapatam.

Question 33.
In which battle the Marathas were defeated by the Company?
Answer:
The Marathas were defeated in the Third Battle of Panipat in 1761.

Question 34.
Name the Maratha dynasties.
Answer:

  • Sindhia,
  • Holkar,
  • Gaikwad,
  • Bhonsle.

Question 35.
Name two famous Maratha statesmen of the late eighteenth century.
Answer:
Mahadji Sindhia and Nana Phadnis.

Question 36.
Name the Governor-General who initiated the policy of “paramountcy”.
Answer:
Lord Hastings.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 37.
What was the policy of paramountcy?
Answer:
Under this policy, Company claimed that its authority was paramount or supreme, hence its power was greater than that of Indian states.

Question 38.
Who was Chennamma?
Answer:
She was Queen of Kitoor in Karnataka.

Question 39.
Who was Rayanna?
Answer:
Rayanna was a poor chowkidar of Sangoli in Kitoor who revolted against the British.

Question 40.
When the Punjab annexed by the Company?
Answer:
In 1849.

Question 41.
Name the Governor-General who brought the Doctrine of Lapse.
Answer:
Lord Dalhousie.

Question 42.
Name any four Kingdoms annexed under the Doctrine of Lapse.
Answer:

  1. Satara,
  2. Sambalpur,
  3. Udaipur,
  4. Nagpur,
  5. Jhansi.

Question 43.
How many Presidencies were there in the British India? Name them.
Answer:
There were three Presidencies :

  1. Bengal,
  2. Madras,
  3. Bombay.

Question 44.
Who was the first Governor-General of India?
Answer:
Warren Hastings.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 45.
Who presided over the civil and criminal courts?
Answer:
The District Collector.

Question 46.
When was the Supreme Court established?
Answer:
The Supreme Court was established in 1773 under the provisions of Regulating Act.

Question 47.
Which new technology aided the Company to become a territorial colonial power?
Answer:
New steam technology.

Question 48.
What facilities did the Company get through the Royal Charter?
Answer:
With this Charter :

  • The Company could venture across the oceans.
  • The Company could look for new lands from which it could collect revenues.
  • The Company could buy goods at cheap price and carry them back to Europe to sell at higher prices.
  • The Company had no Competitor from England.

Question 49.
Why did the European Companies conflict with each other?
Answer:

  • They were trade competitors.
  • The only way the trading Companies could flourish was by eliminating rival competitors.
  • The urge to secure markets, therefore, led to fierce battler between the trading Companies.

Question 50.
How did the Farman issued by Aurangzeb cause loss of revenue for Bengal?
Answer:

  • Aurangzeb’s Farman had granted the Company the right to trade without paying duties.
  • But the Company officials who were carrying individual trade also refused to pay duty.
    This caused enormous loss of revenue for Bengal.

Question 51.
Why did Sirajuddaulah capture Kassimbazar factory of the British?
Answer:

  • The Company was meddling in the political affairs of the province.
  • The Company was involved in fortification of its settlement.
  • The Company was not paying revenues properly.

Question 52.
What was the main reason that Sirajuddaulah lost the Battle of Plassey to the British?
Answer:

  • One of the main reasons for the defeat of the Nawab was that the forces led by Mir Zafar, one of the Sirajuddaulah’s commanders, never fought the battle.
  • Clive had managed to secure his support by promising to make him nawab after crushing Sirajuddaulah.

Question 53.
Why were the Company officials called ‘nabobs’ in Britain?
Answer:

  • The officials who managed to return with wealth led flashy lives in Britain and they flaunted their riches.
  • They were ridiculed as ‘nabobs’ the anglicised version of the Indian word nawab.

Question 54.
Why did the British want to capture Mysore?
Answer:
Following were the reasons :

  • Mysore controlled the profitable trade of the Malabar coast where the Company purchased pepper and cardamom.
  • Tipu stopped the export of sandalwood, pepper and cardamom through the ports of his kingdom.
  • He disallowed the local merchants from trading with the Company.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 55.
Explain the resistance shown by the state of Kitoor against the British annexation.
Answer:

  • When the British tried to annex Kitoor, Rani Chennamma took arms and led an armed struggle against the British. But she was captured and died in prison.
  • Later a poor chowkidar Rayanna carried the resistance. He captured many British camps and destroyed them.

Question 56.
What was Doctrine of Lapse? On what pretext did the Company annex Awadh?
Answer:

  • According to this doctrine, if an Indian ruler dies without a male heir, his kingdom would ‘lapse’, i.e., his kingdom would become the part of the Company.
  • The Company annexed Awadh under the pretext that it was freeing the people from the misgovernment of the Nawab.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 57.
What did the British do to secure their control over the northwest?
Answer:

  1. To secure their control over the northwest, the Company fought wars with Afghanistan.
  2. Between 1838 and 1842, the Company fought wars with Afghanistan and established its rule there indirectly.
  3. It also annexed Sindh in 1843.

Question 58.
What was the Doctrine of Lapse?
Answer:
According to this doctrine, if an Indian ruler dies without a male heir, his kingdom would ‘lapse’ i.e. his kingdom would become the part of the Company.

Question 59.
Discuss the reason that led to fierce battles between the European trading companies in India.
Answer:

  • The European Companies were interested in buying the same things.
  • The fine qualities of Indian silk and cotton had a big market in Europe. Pepper, cloves, cardamom and cinnamon too were in great demand.
  • Competition amongst the European companies increased the cost of these goods that reduced the profit margin.

The only way to retain profit was to eliminate the rivals. Thus, the urge to secure market led to fierce battles between European trading companies in India.

Question 60.
How did the East India Company benefit from the Diwani granted by the Mughal Emperor?
Answer:

  • The Diwani allowed the Company to use the vast revenue resources of Bengal.
  • The Company had no British goods to sell in India. So, it had to import gold and
    silver from Britain for purchasing Indian goods. Now, the revenue obtained through Diwani could be used to purchase goods.
  • Further, the revenue could be used to maintain Company troops and meet the cost of building the Company fort and offices at Calcutta.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Question 61.
Discuss the Anglo-Maratha wars?
Answer:

  • The first Anglo-Maratha war ended in 1782 with the Sabai treaty without any result.
  • The second war (1803-05) resulted in the British gaining Orissa and the territories north of the Yamuna river including Agra and Delhi.
  • The third Anglo-Maratha war (1817-19) ended the Maratha might. The Peshwa was sent to Bithur with a pension.

Question 62.
Why did the British want to secure its northwest frontier? What did it do?
Answer:

  • The British had developed a fear that Russia might expand across Asia and enter India from the northwest.
  • This was because, the Company focused on northwest region and fought wars with Afghanistan, Sindh and Punjab.
  • The Company finally annexed Sindh. It established an indirect control over Afghanistan and in 1849, annexed Punjab.

Question 63.
Under the new British Administrative setup, the Office of Collector became prominent. Discuss.
Answer:

  • The Collector was the administrative head of the new administrative unit, i.e., district.
  • His main job was to collect revenue and taxes and maintain law and order.
  • In furnishing its duty, Collector took help of judges, police officers and darogas.
  • His office – the Collectorate – became the new centre of power and patronage that steadily replaced previous holders of authority.

Question 64.
Write a note on improvements made by Hastings in Indian Judiciary system.
Answer:

  • Each district had two courts – a criminal court and a civil court.
  • Maulvis and Pandits interpreted Indian laws before the European district Collectors who presided over Civil Courts. The Criminal Court was brought under the supervision of the Collector.
  • He got the Hindu and Muslim laws translated and codified.
  • A new Supreme Court was established at Calcutta under the Regulating Act.
  • The Court of Appeal – the Sadar Nizamat Adalat was also set up at Calcutta.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

Multiple Choice Questions (MCQs)

1. Tick the incorrect statement in the following.
(a) After the death of Aurangzeb, powerful regional kingdoms emerged in various parts of India.
(b) In spite of powerful regional kingdoms, Delhi continued to function as an effective centre in the 18th century.
(c) The British originally came to India as a small trading company.
(d) After Aurangzeb, there was no powerful Mughal ruler.
Answer:
(b) In spite of powerful regional kingdoms, Delhi continued to function as an effective centre in the 18th century.

2. Which of the following statements is not correct?
(а) The East India Company came into being in 1600 when Queen Victoria (the ruler of England) granted it the sole right to trade with the East.
(b) The first English factory was set up on the banks of the river Hugli in 1651.
(c) The village of Kalikata grew into the city of Calcutta or Kolkata as it is known today.
(d) Aurangzeb issued a farman to the East India Company granting it the right to trade duty free.
Answer:
(а) The East India Company came into being in 1600 when Queen Victoria (the ruler of England) granted it the sole right to trade with the East.

3. Murshid Quli Khan was the Nawab of:
(a) Carnatic
(b) Bihar
(c) Bengal
(d) Awadh
Answer:
(c) Bengal.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

4. The famous Battle of Plassey was fought between Robert Clive and Sirajuddaulah in-
(a) 1857
(b) 1764
(c) 1657
(d) 1757
Answer:
(d) 1757.

5. Which of the following statements is not correct?
(a) The Battle of Plassey was the first major victoiy, the Company won in India.
(b) After Sirajuddaulah’s death, Mir Qasim was made the Nawab of Bengal by the Company.
(c) Tipu Sultan was died defending his capital Seringapatam in 1799.
(d) Lord Dalhousie devised a policy that came to be known as the Doctrine of Lapse.
Answer:
(b) After Sirajuddaulah’s death, Mir Qasim was made the Nawab of Bengal by the Company.

6. When did the Battle of Buxar take place?
(a) 1761
(b) 1764
(c) 1757
(d) 1760
Answer:
(b) 1764

7. Which ruler is known as Tiger of Mysore?
(a) Tipu Sultan
(b) Haider Ali
(c) Bahadur Shah Jafar
(d) Sirajuddaula
Answer:
(a) Tipu Sultan

Glossary:

→ Mercantile – A business enterprise that makes profit primarily by excluding competition in trade, buying goods cheap and selling them at higher prices.

→ Farman-A royal edict, a royal order.

→ Puppet – Literally, a toy that you can move with strings. The term is used disapprovingly to refer to a person who is controlled by someone else.

→ Injunction – Instruction.

→ Subservience – Submissiveness.

→ Confederacy – Alliance.

→ Qazi – A Judge.

Class 8 History Chapter 2 Extra Questions and Answers From Trade to Territory

→ Mufti – A jurist of the Muslim community responsible for expounding the law that the qazi would administer.

→ Impeachment -A trial by the House of Lords in England for charges of misconduct brought against a person in the House of Commons.

→ Dharmashastras – Sanskrit texts prescribing social rules and codes of behaviour composed from C.500 BCE onwards.

→ Sowar – Men on horses.

→ Musket – A heavy gun used by infantry soldiers.

→ Matchlock – An early type of gun in which the powder was ignited by a match.

Extra Questions for Class 8 Social Science

Extra Questions for Class 8 Science with Answers

Extra Questions for Class 8 Science with Answers

Online Education for NCERT Class 8 Science Extra Questions with Answers

  1. Crop Production and Management Class 8 Extra Questions
  2. Microorganisms: Friend and Foe Class 8 Extra Questions
  3. Synthetic Fibres and Plastics Class 8 Extra Questions
  4. Materials: Metals and Non-Metals Class 8 Extra Questions
  5. Coal and Petroleum Class 8 Extra Questions
  6. Combustion and Flame Class 8 Extra Questions
  7. Conservation of Plants and Animals Class 8 Extra Questions
  8. Cell Structure and Functions Class 8 Extra Questions
  9. Reproduction in Animals Class 8 Extra Questions
  10. Reaching the Age of Adolescence Class 8 Extra Questions
  11. Force and Pressure Class 8 Extra Questions
  12. Friction Class 8 Extra Questions
  13. Sound Class 8 Extra Questions
  14. Chemical Effects of Electric Current Class 8 Extra Questions
  15. Some Natural Phenomena Class 8 Extra Questions
  16. Light Class 8 Extra Questions
  17. Stars and the Solar System Class 8 Extra Questions
  18. Pollution of Air and Water Class 8 Extra Questions

Online Education NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2

In Online Education NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 are part of NCERT Solutions for Class 8 Maths. Here we have given NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2.

Board CBSE
Textbook NCERT
Class Class 8
Subject Maths
Chapter Chapter 11
Chapter Name Mensuration
Exercise Ex 11.2
Number of Questions Solved 11
Category NCERT Solutions

NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2

Question 1.
The shape of the top surface of a table is a trapezium. Find its area, if its parallel sides are 1 m and 1.2 man the d perpendicular distance between them is 0.8 m.
Solution.
Area of the top surface of the table
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 1
= \(\frac { 1 }{ 2 } h(a+b)\)
= \(\frac { 1 }{ 2 } \times 0.8\times (1.2+1)\)
= \(0.88{ m }^{ 2 }\)

Question 2.
The area of a trapezium is 34 cm2 and the length of one of the parallel sides is 10 cm and its height is 4 cm. Find the length of the another parallel side.
Solution.
Area of trapezium
= \(\frac { 1 }{ 2 } h(a+b)\)
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 2
⇒ \(34=\frac { 1 }{ 2 } \times 4(10+b)\)
⇒ \(34=2\times (10+b)\)
⇒ \(10+b=\frac { 34 }{ 2 } \)
⇒ 10 + b=17
⇒ b = 17 – 10
⇒ b = 7 cm
Hence, the length of another parallel side is 7 cm.

Question 3.
Length of the fence of a trapezium shaped field ABCD is 120 m. If BC = 48 m, CD = 17 m and AD = 40 m, find the area of this field. Side AB is perpendicular to the parallel sides AD and BC
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 3
Solution.
Fence of the trapezium shaped field ABCD = 120 m
⇒ AB + BC + CD + DA = 120
⇒ AB + 48 + 17 + 40 = 120
⇒ AB + 105 = 120
⇒ AB = 120 – 105
⇒ AB = 15 m
∴ Area of the field
= \(\frac { (BC+AD)\times AB }{ 2 } \)
= \(\frac { (48+40)\times 16 }{ 2 } \) = 660 \({ m }^{ 2 }\)

Question 4.
The diagonal of a quadrilateral shaped field is 24 m and the perpendiculars dropped on it from the remaining opposite vertices are 8 m and 13 m. Find the area of the field.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 4
Solution.
Area of the field
= \(\frac { 1 }{ 2 } d({ h }_{ 1 }+{ h }_{ 2 })\)
= \(\frac { 24\times (8+13) }{ 2 } \) = \(\frac { 24\times 21 }{ 2 } \)
= 12 x 21 = 252\({ m }^{ 2 }\)

Question 5.
The diagonals of a rhombus are 7.5 cm and 12 cm. Find its area.
Solution.
Area of the rhombus
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 5
= \(\frac { 1 }{ 2 } \times { d }_{ 1 }\times { d }_{ 2 }\)
= \(\frac { 1 }{ 2 } \times 7.5\times 12\)
= 45 \({ m }^{ 2 }\)

Question 6.
Find the area of a rhombus whose side is 5 cm and whose altitude is 4.8 cm. If one of its diagonals is 8 cm long, find the length of the other diagonal.
Solution.
Area of the rhombus
= base (b) x altitude (h) = 5
= 5 x 4.8 = 24 \({ cm }^{ 2 }\)
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 6

Question 7.
The floor of a building consists of 3,000 tiles which are rhombus shaped and each of its diagonals are 45 cm and 30 cm in length. Find the total cost of polishing the floor, if the cost per \({ m }^{ 2 }\) is ₹ 4.
Solution.
Area of a tile
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 7

Question 8.
Mohan wants to buy a trapezium shaped field. Its side along the river is parallel to and twice the side along the road. If the area of this field is 10,500 \({ m }^{ 2 }\) and the perpendicular distance between the two parallel sides is 100 m, find the length of the side along the river.
Solution.
Let the length of the side along the road be x m. Then, the length of the side along the river is 2x m.
Area of the field = 10,500 square metres
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 8

Question 9.
Top surface of a raised platform is in the shape of a regular octagon as shown in the figure. Find the area of the octagonal surface.
Solution.
Area of the octagonal surface
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 9
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 10

Question 10.
There is a pentagonal shaped park as shown in the figure. For finding its area Jyoti and Kavita divided it in two different ways.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 11
Find the area of this park using both ways. Can you suggest some other way of finding its area ?
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 12
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 13

Question 11.
Diagram of the adjacent picture frame has outer dimensions = 24 cm x 28 cm and inner dimensions 16 cm x 20 cm. Find the area of each section of the frame, if the width of each section the same.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 14
Solution.
NCERT Solutions for Class 8 Maths Chapter 11 Mensuration Ex 11.2 15

 

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NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals

NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 4
Chapter Name Materials: Metals and Non-Metals
Number of Questions Solved 11
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals

NCERT TEXTBOOK EXERCISES

Question 1.
Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Answer.
(a) Zinc.

Question 2.
Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Answer.
(c) Generally, metals are ductile.

Question 3.
Fill in the blanks.

  1. Phosphorus is a very ……… non-metal.
  2. Metals are ……….. conductors of heat and
  3. Iron is …….. reactive than copper.
  4. Metals react with acids to produce ………………. gas.

Answer.

  1. reactive
  2. good, electricity
  3. more
  4. hydrogen.

Question 4.
Mark T’ if the statement is true and ‘F’ if it is false.
(a ) Generally, non-metals react with acids. [   ]
(b) Sodium is a very reactive metal. [    ]
(c) Copper displaces zinc from zinc sulphate solution. [   ]
(d) Coal can be drawn into wires. [    ]
Answer.
(a) F
(b) T
(c) F
(d) F.

Question 5.
Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.

Properties Metals Non-metals

1. Appearance

2.  Hardness

3.  Malleability

4.  Ductility

5.  Heat Conduction

6.  Conduction of Electricity

Answer.

Properties Metals Non-metals
1. Appearance have metallic luster dull
2. Hardness hard soft
3. Malleability malleable non-malleable
4. Ductility ductile non-ductile
5. Heat Conduction good conductors bad conductors
6. Conduction of Electricity good conductors bad conductors/insulators

Question 6.
Give reasons for the following.

  1. Aluminium foils are used to wrap food items.
  2. Immersion rods for heating liquids are made up of metallic substances.
  3. Copper cannot displace zinc from its salt solution,
  4. Sodium and potassium are stored in kerosene.

Answer.

  1. It maintains the temperature of food items intact as it is a good conductor of heat.
  2. Metals are good conductors of electricity. That is why immersion rods are made up of metals.
  3. It is because copper is less reactive than zinc.
  4. It is because sodium and potassium react vigorously when coming in contact with air or water.

Question 7.
Can you store the lemon pickle in an aluminium utensil? Explain.
Answer.
Aluminium is a metal. Metals are more reactive to acids. That is why acidic foodstuffs like lemon pickles must not be stored in aluminium utensils.

Question 8.
Match the substances given in Column A with their uses given in Column B.

Column A

 Column B
(i) Gold (a) Thermometers
(ii) Iron (b) Electric wire
(iii) Aluminium (c) Wrapping food
(iv) Carbon (d) Jewellery
(v) Copper (e) Machinery
(vi) Mercury (f) Fuel

Answer.

Column A Column B
(i) Gold (d) Jewellery
(ii) Iron (e) Machinery
(iii) Aluminium (c) Wrapping food
(iv) Carbon (f) Fuel
(v) Copper (b) Electric wire
(vi) Mercury (a) Thermometers

Question 9.
What happens when
(1) Dilute sulphuric acid is poured on a copper plate?
(2) Iron nails are placed in copper sulphate solution?
Write word equations of the reactions involved.
Answer.

  1. Copper sulphate is formed and hydrogen gas is released.
    Copper + dil. sulphuric acid → Copper sulphate + Hydrogen (gas)
  2. Brown coating is deposited on the iron nails. This is because of the displacement of copper from copper sulphate solution by iron.
    Iron + Copper sulphate (solution) → Iron sulphate (solution) + Copper

Question 10.
Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(1) How will she find the nature of the gas?
(2) Write down word equations of all the reactions taking place in this process.
Answer.

  1. She will bring a wet litmus paper in contact with the gas. If the gas turns wet blue litmus paper into red, the gas will be acidic.
    1. Carbon + Oxygen → Carbon dioxide.
    2. Carbon dioxide + Water → Carbonic acid.

Question 11.
One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. The next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?
Answer.
In polishing, the jeweller put the gold jewellery in a mild acidic solution, which in reaction with acid goes into the solution. So, in this process, a certain amount of gold is lost to the acidic solution.

We hope the NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals, drop a comment below and we will get back to you at the earliest

NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 3
Chapter Name Synthetic Fibres and Plastics
Number of Questions Solved 15
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics

NCERT TEXTBOOK EXERCISES

Question 1.
Explain why some fibres are called synthetic.
Answer.
Since man-made fibres are synthesised from petrochemicals, they are called synthetic fibres.

Question 2.
Mark the correct answer.
Rayon is different from synthetic fibres because
(a) it has a silk-like appearance
(b) it is obtained from wood pulp
(c) its fibres can also be woven like those of natural fibres
Answer.
(b) It is obtained from wood pulp.

Question 3.
Fill in the blanks with appropriate words:

  1. Synthetic fibres are also called…………. or……………fibres.
  2. Synthetic fibres are synthesised from raw material called………..
  3. Like synthetic fibres, plastic is also a …………..

Answer.

  1. artificial, man-made.
  2. petrochemicals.
  3. polymer.

Question 4.
Give examples which indicate that nylon fibres are very strong.
Answer.
They are used to make parachutes, and ropes for rock climbing.

Question 5.
Explain why plastic containers are favoured for storing food.
Answer.
Three main advantages of using plastic containers for storing food are:

  1. They do not react with food items.
  2. They do not get rusted.
  3. They are light, strong and durable.

Question 6.
Explain the difference between thermoplastic and thermosetting plastics.
Answer.
Thermoplastics can be softened on heating and can be bent easily whereas thermosetting plastics cannot be softened on heating and breaks when forced to bend.

Question 7.
Explain why the following are made of thermosetting plastics.
(1) Saucepan handles
(2) Electric plugs Iswitches /plugboards.

Answer.
The above articles are made up of bakelite (a thermosetting plastic) because it is—

  1. the bad conductor of heat.
  2. poor conductor of electricity.

Question 8.
Categorise the materials of the following products into ‘can be recycled’ and ‘cannot be recycled’:
Telephone instruments, plastic toys, cooker handles, carry bags, ballpoint pens, plastic bowls, plastic covering on electrical wires, plastic chairs, electrical switches.
Answer.

Can be recycled Cannot be recycled
Toys carry bags, plastic bowls, electric wire covering, plastic chairs. Telephone instruments, cooker handles, ballpoint pens, electrical switches.

Question 9.
Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason.
Answer.
I would advise Rana to buy cotton shirts as cotton shirts absorb the sweat and thus endorse cooling. Besides, they also provide aeration.

Question 10.
Give examples to show that plastics are noncorrosive in nature.
Answer.

  1. It does not react with the chemical or other items stored in the containers made of it.
  2. It does not get rusted when exposed to moisture and air.
  3. It does not decompose when left in open for a long period.

Question 11.
Should the handle and bristles of a toothbrush be made of the same material? Explain your answer.
Answer.
The handles and bristles of a toothbrush should be made of a material which has lightweight good strength and is hygiene. “But the bristles should be soft enough so that ” they do not harm gums while the handle should be quite stiff so that it may not get bent while brushing.

Question 12.
‘Avoid plastics as far as possible.’ Comment on this advice.
Answer.
Since plastic takes several years to decompose, it is not environment friendly. It causes environmental pollution. Besides, when the synthetic material is burnt it takes a long time to get completely burnt. In the process, it releases a lot of poisonous fumes into the atmosphere causing air pollution.

Question 13.
Match the terms of Column A correctly with the phrases given in Column B.

Column A Column B
(i) Polyester (a) Prepared by using wood pulp
(ii) Teflon (b) Used for making parachutes and stockings
(iii) Rayon (c) Used to make non-stick cookwares
(iv) Nylon (d) Fabrics do not wrinkle easily

Answer.

Column A Column B
(i) Polyester (d) Fabrics do not wrinkle easily
(ii) Teflon (c) Used to make non-stick cookwares
(iii) Rayon (a) Prepared by using wood pulp
(iv) Nylon (b) Used for making parachutes and stockings


Question 14.
‘Manufacturing synthetic fibres are actually helping conservation of forests. ’ Comment.
Answer.
The synthetic fibres are made up of petrochemicals. So, manufacturing synthetic fibres does not depend upon plants. These synthetic fibres cater to the need of people up to great extent. Thus, the forests are not destroyed to manufacture clothes and other items. So, indirectly, we can come to the conclusion that manufacturing synthetic fibres is actually helping the conservation of forests.

Question 15.
Describe an activity to show that thermoplastic is a poor conductor of electricity.
Answer.
A thermoplastic (or plastic) is a poor conductor of electricity as shown in Fig. 3.3.
If we place a piece of copper in the gap touching points A and B (in Fig. 3.3), we observe that bulb glow. If we place plastic in the gap between A and B, we observe that the bulb will not glow. It means plastic is a poor conductor.
NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics 1

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NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 2
Chapter Name Microorganisms: Friend and Foe
Number of Questions Solved 9
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe

NCERT TEXTBOOK EXERCISES

Question 1.
Fill in the blanks.

  1. Microorganisms can be seen with the help of a………………
  2. Blue-green algae fix………….. directly from the air and enhance the fertility of the soil.
  3. Alcohol is produced with the help of……………….
  4. Cholera is caused by………………….

Answer.

  1. microscope
  2. nitrogen
  3. yeast
  4. bacteria.

Question 2.
Tick the correct answer.
(a) Yeast is used in the production of
(i) sugar
(ii) alcohol
(iii) hydrochloric acid
(iv) oxygen
Answer.
(ii) alcohol

(b) The following is an antibiotic
(i) Sodium bicarbonate
(ii) Streptomycin
(iii) Alcohol
(iv) Yeast
Answer.
(ii) Streptomycin

(c) Carrier of malaria-causing protozoan is
(i) female Anopheles mosquito
(ii) cockroach
(iii) housefly
(iv) butterfly
Answer.
(i) female Anopheles mosquito

(d) The most common carrier of communicable diseases is
(i) ant
(ii) housefly
(iii) dragonfly
(iv) spider
Answer.
(ii) housefly

(e) The bread or idli dough rises because of
(i) heat
(ii) grinding
(iii) growth of yeast cells
(iv) kneading
Answer.
(iii) growth of yeast cells

(f) The process of conversion of sugar into alcohol is called
(i) nitrogen fixation
(ii) moulding
(iii) fermentation
(iv) infection
Answer.
(iii) fermentation.

Question 3.
Match the organisms in Column A with their action in Column B.

Column A Column B

(i) Bacteria

(ii) Rhizobium

(iii) Lactobacillus

(iv)Yeast

(v) A protozoan

(vi) A virus

(a) Fixing nitrogen

(b) Setting of curd

(c) Baking of bread

(d) Causing malaria

(e) Causing cholera

(f) Causing AIDS

(g) Producing antibodies

Answer.

Column A Column B
(i) Bacteria (e) Causing cholera
(ii) Rhizobium (a) Fixing nitrogen
(iii) Lactobacillus (b) Setting of curd
(iv) Yeast (c) Baking of bread
(v) A protozoan (d) Causing malaria
(vi) A virus (f) Causing AIDS

Question 4.
Can microorganisms be seen with the naked eye? If not, how can they be seen?
Answer.
No, we cannot see microorganisms with unaided eyes. They can be seen with the help of a microscope.

Question 5.
What are the major groups of microorganisms?
Answer.
Microorganisms are classified into four major groups based on their size. These are:

  1. Bacteria
  2. Fungi
  3. Protozoa
  4. Some algae.

Viruses are another type of microorganisms.
NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe 1
NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe 2
NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe 3
NCERT Solutions for Class 8 Science Chapter 2 Microorganisms Friend and Foe 4

Question 6.
Name the microorganisms which can fix atmospheric nitrogen in the soil.
Answer.
They are

  • Rhizobium
  • Azobhcter
  • blue-green algae (such as Anabaena and Nostoc), etc.

Question 7.
Write 10 lines on the usefulness of microorganisms in our lives.
Answer.
Microorganisms are useful for us in many ways e.g.,

  1. the bacterium, lactobacillus converts milk into curd.
  2. bacteria are also involved in the making of cheese.
  3. Acetobacter acetic is used for the production of acetic acid from alcohol.
  4. Yeast is used for the commercial production of alcohol and wine.
  5. Antibiotics are manufactured by growing specific microorganisms.
  6. Some bacteria fix atmospheric nitrogen and increase soil fertility.
  7. Bacteria are used in the preparation of medicines like antibiotics and vaccines.
  8. Bacteria are used in the preservation of pickles and many other food items.
  9. Yeast is also used in the baking industry for making bread, pastries, and cakes.
  10. They act as cleansing agents and decompose the waste products into manure.

Question 8.
Write a short paragraph on the harmful effects of microorganisms.
Answer.
The harms caused by microorganisms are as follows:

  1. Many communicable diseases, such as cholera, common cold, chickenpox, tuberculosis, etc., are caused by microorganisms.
  2. Malaria is caused by a microorganism called Plasmodium carried by the female Anopheles mosquito.
  3. The Female Aedes mosquito acts as a carrier of the dengue virus.
  4. Anthrax is a dangerous human and cattle disease caused by a bacterium called Bacillus anthracis.
  5. Several microorganisms cause diseases in plants like wheat, rice, potato, sugarcane, orange, apple, etc., and reduce the yield of the crops.
  6. Food poisoning is also caused by microorganisms. They make food poisonous by producing toxic substances in the food.

Question 9.
What are antibiotics? What precautions must be taken while taking antibiotics?
Answer.
The medicines, that kill or stop the growth of the disease-causing microorganisms, are called antibiotics. Streptomycin, tetracycline, erythromycin, etc. are some of the commonly known antibiotics which are made from fungi and bacteria.
The precautions to be taken while taking antibiotics are as follows :

  1. These medicines should be taken only on the advice of a qualified doctor.
  2. One must complete the course prescribed by the doctor.
  3. If anybody takes antibiotics when not needed, his/her body may develop resistance against that antibiotic.

We hope the NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe, drop a comment below and we will get back to you at the earliest

NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management

NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management.

Board CBSE
Textbook NCERT
Class Class 8
Subject Science
Chapter Chapter 1
Chapter Name Crop Production and Management
Number of Questions Solved 11
Category NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management

NCERT TEXTBOOK EXERCISES

Question 1.
Select the correct word from the following list and fill in the blanks, float, water, crop, nutrients, preparation

(a) The same kind of plants grown and cultivated on a large scale at a place is called __________.
Answer:
Crop

(b) The first step before growing crops is ___________ of the soil.
Answer:
Preparation

(c) Damaged seeds would ___________ on top of water.
Answer:
Float

(d) For growing a crop, sufficient sunlight, __________ and __________ from the soil are essential.
Answer:
water
Nutrients

Question 2.
Match items in column A with those in column B.

Column A Column B
(i) Kharif crops (a) Food for cattle
(ii) Rabi crops (b) Urea and super phosphate
(iii) Chemical fertilisers (c) Animal excreta, cow dung, urine and plant waste
(iv) Organic manure (d) Wheat, gram, pea
(e) Paddy and maize

 

 

 

 

 

Answer.

Column A Column B
(i) Kharif crops (e) Paddy and maize
(ii) Rabi crops (d) Wheat, gram, pea
(iii) Chemical fertilisers (b) Urea and superphosphate
(iv) Organic manure (c) Animal excreta, cow dung, urine, and plant waste

 

 

 

 

 

Question 3.
Give two examples of each:

  1. Kharif crop
  2. Rabi crop

Answer.

  1. Paddy, maize
  2. Wheat, gram.

Question 4.
Write a paragraph in your own words on each of the following:

  1. Preparation of soil
  2. Sowing
  3. Weeding
  4. Threshing

Answer.
(1) Preparation of soil: It is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep in the soil. The process of loosening and turning of soil is called tilling or ploughing which is done by a plough. Ploughs are made of wood or iron. The ploughed fields may have big pieces of soil called crumbs. These crumbs are broken and the field is levelled for sowing and for irrigation.

(2) Sowing: It is the process of putting seeds in the soil. For this purpose, good quality seeds are selected which are clean, healthy, of good variety, and give a high yield. Seeds are sown with the help of a traditional funnel-shaped tool or a seed drill. An appropriate distance between the seeds is also important to avoid overcrowding.

(3) Weeding: In a crop field many other undesirable plants may grow naturally along with the crop. These are called weeds. Weeds should be removed to protect the crops. The process of removal of weeds is called weeding. Weeding is necessary because weeds compete with the cultivated plants for space, light, water, and nutrients. Some weeds are poisonous for animals and human beings. Tilling before sowing of crops helps in uprooting and killing of weeds, which may then dry up and get mixed with the soil. The weeds must be removed before they produce flowers and seeds. They are removed either manually or by using weedicides.

(4) Threshing: After harvesting, the crops are threshed for removing grain seeds from the chaff. This is carried out with the help of a thresher or a machine called ‘combine’ which is in fact a combined harvester and thresher.

Question 5.
Explain how fertilisers are different from manure.
Answer.

Fertilisers Manure

1.  Fertilisers are chemicals which are rich in a particular nutrient like nitrogen, phosphorus, and potassium.

2. Excessive use of fertilisers destroys soil fertility.

1. Manures are decomposed organic matter obtained from plant or animal wastes.

2. The use of manures improves soil texture as well as its water-holding capacity.

Question 6.
What is irrigation? Describe two methods of irrigation which conserve water.
Answer.
The supply of water to crops at different intervals is called irrigation. The two methods of irrigation in which water is conserved are the sprinkler system and the drip system.

(1) Sprinkler system: This system is mostly used on uneven lands where water is available in smaller quantities. In this system, perpendicular pipes having rotating nozzles on the top are joined to the main pipeline at regular intervals. When water is allowed to flow through the main pipe under pressure with the help of a pump, it escapes from the rotating nozzles. It is sprinkled on the crop as if it is raining. It is very useful for sandy soil.

(2) Drip system: In this system, the water falls drop by drop just at the position of the roots. So, it is called a drip system. It is the best technique for watering fruit plants, gardens, trees, etc. This system consists of the main pipe to which lateral pipes are joined. The specially prepared nozzles are attached to these lateral pipes. The nozzles are grounded just near the roots of the plants. It provides water drop by drop to plants. Water is not wasted at all. So, it is a boon in regions where the availability of water is poor.

Question 7.
If wheat is sown in the Kharif season, what would happen? Discuss.
Answer.
The best season for the wheat crops is from November/December to March/April. If it is sown in the Kharif season its production will be decreased considerably.

Question 8.
Explain how soil gets affected by the continuous plantation of crops in a field.
Answer.
The continuous growing of crops makes the soil deficient in certain nutrients. To avoid this, the following practices should be facilitated:

  1. Crop rotation
  2. Manuring the soil
  3. Leaving field fallow

Question 9.
What are weeds? How can we control them?
Answer.
The undesirable plants in the field that grow naturally are called weeds. Weeds must be removed, otherwise, our own crop plants may not get sufficient water, nutrients, space, and light. So, they are removed either by manual method or by using weedicides.

The manual removal includes physical removal of weeds by uprooting or cutting them close to the ground from time to time. This is done with the help of a khurpi or a harrow. By using weedicides also, we can remove weeds. These weedicides damage only weeds and do not harm crops, e.g., 2, 4-D.

Question 10.
Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management 1
Answer.
NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management 2
Question 11.
Complete the following word puzzle with the help of clues below.
Down
1. Providing water to the crops.
2. Keeping crop grains for a long time under proper conditions.
5. Certain plants of the same kind grown on a large scale.
Across
3. A machine used for cutting the matured crop.
4. A rabi crop that is also one of the pulses.
6. A process of separating the grain from the chaff.
Answer.
NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management 3

We hope the NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management, drop a comment below and we will get back to you at the earliest.