Murali

NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals.

Board	CBSE
Textbook	NCERT
Class	Class 7
Subject	Science
Chapter	Chapter 2
Chapter Name	Nutrition in Animals
Number of Questions Solved	13
Category	NCERT Solutions

NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals

Question 1.
Fill in the blanks:

1. The main steps of nutrition in humans are ……., ………., ………., ………, and ………….
2. The largest gland in the human body is ………..
3. The stomach releases hydrochloric acid and ……… juices which act on the food.
4. The inner wall of the small intestine has many finger-like outgrowths called ……….
5. Amoeba digests its food in the ………..

Answer:

1. ingestion, digestion, absorption, assimilation, and egestion.
2. liver
3. digestive
4. villi
5. food vacuole.

Question 2.
Mark ‘T’ if the statement is true and ‘F’ if it is false:

1. Digestion of starch starts in the stomach. (T/F)
2. The tongue helps in mixing food with saliva. (T/F)
3. The gall bladder temporarily stores bile. (T/F)
4. The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)

Answer:

1. F
2. T
3. T
4. T

Question 3.
Tick (√) mark the correct answer in each of the following:
(a) Fat is completely digested in the
(i) stomach
(ii) mouth
(iii) small intestine
(iv) large intestine

(b) Water from the undigested food is absorbed mainly in the
(i) stomach
(ii) food pipe
(iii) small intestine
(iv) large intestine
Answer:
(a) (iii) Small intestine
(b) (iv) Large intestine.

Question 4.
Match the items of Column I with those given in Column II:

Column I	Column II
Food components	Product(s) of digestion
Carbohydrates	Fatty acids and glycerol
Proteins	Sugar
Fats	Amino acids

Answer:

Column I	Column II
Food components	Product(s) of digestion
Carbohydrates	Sugar
Proteins	Amino acids
Fats	Fatty acids and glycerol

Question 5.
What are villi? What are their location and function?
Answer:
The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi. Villi are located in the small intestine. The villi increase the surface area for absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials.

Question 6.
Where is the bile produced? Which component of the food does it help to digest?
Answer:
Bile is produced in the liver. The bile juice is stored in a sac called the gall bladder. Bile plays an important role in the digestion of fats.

Question 7.
Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.
Answer:
Cellulose is a type of carbohydrate that can be digested by ruminants but not by humans. Ruminants have a large sac-like structure called rumen which is present in between the small intestine and large intestine. The cellulose is digested here by the action of certain bacteria which are not present in humans.

Question 8.
Why do we get instant energy from glucose?
Answer:
Because glucose can easily breakdown in the cell with the help of oxygen and gives carbon dioxide, water, and energy.

Question 9.
Which part of the digestive canal is involved in:

1. absorption of food ……..
2. chewing of food …….
3. the killing of bacteria …….
4. complete digestion of food ………
5. formation of faeces ……..

Answer:

1. Small intestine
2. Mouth
3. Stomach
4. Small intestine
5. Large intestine.

Question 10.
Write one similarity and one difference between the nutrition in amoeba and human beings.
Answer:

1. Similarity: Both amoeba and humans use digestive juices to digest food.
2. Difference: Human needs to chew food, whereas, an amoeba, there is no chewing.

Question 11.
Match the items of Column I with suitable items in Column II

Column I	Column II
(a) Salivary gland	(i) Bile juice secretion
(b) Stomach	(ii) Storage of undigested food
(c) Liver	(iii) Saliva secretion
(d) Rectum	(iv) Acid release
(e) Small intestine	(v) Digestion is completed
(f) Large intestine	(vi) Absorption of water
	(Vii) Release of faeces

Answer:

Column I	Column II
(a) Salivary gland	(iii) Saliva secretion
(b) Stomach	(iv) Acid release
(c) Liver	(i) Bile juice secretion
(d) Rectum	(ii) Storage of undigested food
(e) Small intestine	(v) Digestion is completed
(f) Large intestine	(vi) Absorption of water

 Question 12.
Label figure of the digestive system.
Answer:

Fig. Human digestive system

Question 13.
Can we survive only on raw, leafy vegetables/grass? Discuss.
Answer:
No. Because to live a healthy life, we need a complete balance of all nutrients. Raw leafy vegetables/grass may have cellulose which can not be digested by us. So, we cannot survive only on raw, leafy vegetables/grass.

We hope the NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System.

Board	CBSE
Textbook	NCERT
Class	Class 8
Subject	Science
Chapter	Chapter 17
Chapter Name	Stars and the Solar System
Number of Questions Solved	16
Category	NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System

NCERT TEXTBOOK EXERCISES

Choose the correct answer in Questions 1-3:

Question 1.
Which of the following is NOT a member of the solar system?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet
Answer.
(c) A constellation.

Question 2.
Which of the following is NOT a planet of the Sun?
(a) Sirius
(b) Mercury
(c) Saturn
(d) Earth
Answer.
(a) Sirius.

Question 3.
Phases of the moon occur because:
(a ) we can see only that part of the moon which reflects light towards us.
(b) our distance from the moon keeps changing.
(c) the shadow of the Earth covers only a part of the moon’s surface.
(d) the thickness of the moon’s atmosphere is not constant.
Answer.
(a) we can see only that part of the moon which reflects light towards us.

Question 4.
Fill in the blanks:

1. The planet which is farthest from the Sun is………….
2. The planet which appears reddish in colour is…………
3. A group of stars that appear to form a pattern in the sky is known as a……………
4. A celestial body that revolves around a planet is known as…………
5. Shooting stars are actually not…………..
6. Asteroids are found between the orbits of and.…………

Answer.

1. Neptune
2. Mars
3. constellation
4. satellite
5. meteors
6. Mars, Jupiter.

Question 5.
Mark the following statements as True (T) or False (F):

1. Pole star is a member of the solar system.   (   )
2. Mercury is the smallest planet in the solar system. (   )
3. Uranus is the farthest planet in the solar system.   (   )
4. INSAT is an artificial satellite.   (   )
5. There are nine planets in the solar system.    (   )
6. Constellation Orion can be seen only with a telescope.   (   )

Answer.

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

Question 6.
Match items in column A with one or more items in column B.

Answer.

Question 7.
In which part of the sky can you find Venus if it is visible as an evening star?
Answer.
Venus appears in the western sky just after sunset.

Question 8.
Name the largest planet of the solar system.
Answer.
Jupiter (Brihaspati).

Question 9.
What is a constellation? Name any two constellations.
Answer.
A group of stars that has a recognizable shape is called a constellation. Ursa Major and Orion are two examples of constellations.

Question 10.
Draw sketches to show the relative positions of prominent stars in:
(a) Ursa Major and (b) Orion.
Answer.

Question 11.
Name two objects other than planets which are members of the solar system.
Answer.
Satellites and asteroids are the objects that too, are members of the Solar system.

Question 12.
Explain how you can locate the Pole Star with the help of Ursa Major.
Answer.
Pole stars can be located with the help of the two stars at the end of Ursa Major. Imagine a straight line passing through these stars as shown in Fig. 17.2. Extend this imaginary line towards the north direction. (About five times the distance between the two stars). This line will lead to a star which is not too bright. This is the Pole Star.

Question 13.
Do all the stars in the sky move? Explain.
Answer.
No, no star moves in the sky. They appear to move from east to west because the Earth rotates from west to east about its axis.

Question 14.
Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light-years away from the Earth?
Answer.
The distance between stars is so large that it cannot be expressed in terms of a kilometer. That is why very large distances, are expressed in another unit known as light year. One light-year is the distance traveled by light in one year. If the distance of a star is eight light-years, it means that this distance is the distance traveled by light in eight years.

Question 15.
The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accommodate?
Answer.

Question 16.
Boojho made the following sketch (See Fig. 17.29 of NCERT) of the solar system.
Is the sketch correct? If not, correct it.
Answer.
It is not correct. Figure 17.3 is a correct sketch of the solar system.

We hope the NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 17 Stars and the Solar System, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 16 Light are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 16 Light.

Board	CBSE
Textbook	NCERT
Class	Class 8
Subject	Science
Chapter	Chapter 16
Chapter Name	Light
Number of Questions Solved	17
Category	NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 16 Light

NCERT TEXTBOOK EXERCISES

Question 1.
Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room? Explain.
Answer.
We cannot see objects in the darkroom. But, we can see objects outside the room, in case there is light outside the room. It is so because to see an object, we need light which gets reflected from the object and enters our eyes.

Question 2.
Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?
Answer.

Regular reflection	Diffused reflection
1. Occurs from shiny and smooth surfaces. 2. Reflected rays are parallel to each other.	1. Occurs from unpolished and rough surfaces. 2. Reflected rays are not parallel to each other.

No, diffused reflection does not mean, failure of the laws of reflection. It is due to irregularities in the reflecting surface, like that of cardboard.

Question 3.
Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case.

1. Polished wooden table
2. Chalk powder
3. Cardboard surface
4. Marble floor with water spread over it
5. Mirror
6. Piece of paper

Answer.

1. Polished Wooden Table: Regular reflection will take place. This is because a polished wooden table will have a plane surface.
2. Chalk Powder: Diffused reflection because the surface of the chalk powder is not smooth.
3. Cardboard Surface: Diffused reflection since cardboard has a rough surface,
4. Marble Floor with Water Spread Over it: Regular reflection as it will act as a plane surface.
5. Mirror: Regular reflection because the mirror has a shiny surface which is even.
6. Piece of Paper: Diffused reflection because the surface of the paper is rough.

Question 4.
State the laws of reflection.
Answer.
The laws of reflection are as follows:

1. The angle of reflection is equal to the angle of incidence.
2. The incident ray, the normal at the point of incidence, and the reflected ray all lie in the same plane.

Question 5.
Describe an activity to show that the incident ray, the reflected ray, and the normal at the point of incidence lie in the same plane.
Answer.

Question 6.
Fill in the blanks in the following:

1. A person 1 m in front of a plane mirror seems to be…….. m away from his image.
2. If you touch your………..ear with your right hand in front of a plane mirror it will be seen in the mirror that your right ear is touched with
3. The size of the pupil becomes………………..when you see in dim light.
4. Night birds have…………..cones than rods in their eyes.

Answer.

1. 2
2. left, left hand
3. large
4. lesser (fewer).

Choose the correct option in Questions 7 and 8.

Question 7.
The angle of incidence is equal to the angle of reflection:
(a) Always
(b) Sometimes
(c) Under special conditions
(d) Never
Answer.
(a) Always.

Question 8.
The image formed by a plane mirror is
(a) virtual, behind the mirror and enlarged,
(b) virtual, behind the mirror and of the same size as the object.
(c) real at the surface of the mirror and enlarged.
(d) real, behind the mirror and of the same size as the object.
Answer.
(b) Virtual, behind the mirror and of the same size as the object.

Question 9.
Describe the construction of a kaleidoscope.
Answer.
A kaleidoscope is an optical instrument used to see a number of beautiful patterns. It is made up of a circular cardboard tube or tube of thick chart paper in which rectangular mirror strips are joined together to form a prism. At one end of the tube, touching these mirrors, a circular plane glass plate is fixed and several, small pieces of colored glass (broken pieces of colored bangles) are placed upon it. This end is closed by a ground glass plate and beautiful patterns are seen through the other end of the kaleidoscope.

Question 10.
Draw a labelled sketch of the human eye.
Answer.

Question 11.
Gurmit wanted to perform, activity 16.8 (NCERT) using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher’s advice?
Answer.
Laser rays can cause a permanent defect in the eye. Thus, his friend will lose her eyesight if a laser torch is directed over her eyes.

Question 12.
Explain how you can take care of your eyes.
Answer.
The following measures should be taken to keep our eyes healthy and free from any defect:

1. We should not look at the sun or a powerful light source directly.
2. We should not try to see in too little or too much light. It is bad for the eyes. Insufficient light causes eye strain and headaches.
3. Too much light, like that of the sun, or powerful lamps, can injure the retina, which is very delicate.
4. If advised, suitable spectacles should be used.
5. We should wash our eyes frequently with clean water.
6. We should always read from a normal distance for distinct vision and not by bringing the book too close or keeping it too far.
7. We should never rub our eyes if any small particle of dust goes into the eyes. Instead, eyes should be washed with clean water and if the condition does not improve, a doctor should be consulted.
8. If food is deficient in some components, the eye may also suffer. Lack of vitamin A in our diet is responsible for many eye troubles. Most common amongst thorns is night blindness. Therefore, to get rid of this, we must include in our diet components that have vitamin A.

Question 13.
What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?
Answer.

Question 14.
How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?
Answer.
The infinite number of images of the candle will be formed if it is placed between two parallel plane mirrors.

Question 15.
Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30° as shown in Fig. 16.5. Draw the reflected ray from the second mirror.

Answer.

Question 16.
Boojho stands at A just on the side of a plane mirror as shown in Fig. 16.6.
Can he see himself in the mirror? Also can he see the image of objects situated at P, Q and R?

Answer.
No, He can see images of objects at P but not of Q and R.

Question 17.
(a) Find out the position of the image of an object situated at A in the plane mirror (Fig. 16.7).
(b) Can Paheli at B see this image?
(c) Can Boojho at C see this image?
(d) When Paheli moves from B to C, where does the image of A move?

Answer.
(a) Fig. 16.7 (a)
(b) Yes
(c) Yes
(d) No change as the position of A is not changing

We hope the NCERT Solutions for Class 8 Science Chapter 16 Light helps you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 16 Light, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 9 Soil are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 9 Soil.

Board	CBSE
Textbook	NCERT
Class	Class 7
Subject	Science
Chapter	Chapter 9
Chapter Name	Soil
Number of Questions Solved	10
Category	NCERT Solutions

NCERT Solutions for Class 7 Science Chapter 9 Soil

Tick the most suitable answer in questions 1 and 2.
Question 1.
In addition to the rock particles, the soil contains
(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants
Answer:
(iii) minerals, organic matter, air and water

Question 2.
The water holding capacity is the highest in
(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam
Answer:
(ii) clayey soil

Question 3.
Match the items in Column I with those in Column II :

Column I	Column II
(i) A home for living organisms	(a) Large particles
(ii) Upper layer of the soil	(b) All kinds of soil
(iii) Sandy soil	(c) Dark in colour
(iv) Middle layer of the soil	(d) Small particles and packed tight
(v) Clayey soil	(e) Lesser amount of humus

Answer:

Column I	Column II
(i) A home for living organisms	(b) All kinds of soil
(ii) Upper layer of the soil	(c) Dark in colour
(iii) Sandy soil	(a) Large particles
(iv) Middle layer of the soil	(e) Lesser amount of humus
(v) Clayey soil	(d) Small particles and packed tight

Question 4.
Explain how soil is formed?
Answer:

1.  The big and heavy rocks are broken into smaller pieces that come on the surface of the earth.
2. Soil is formed by breaking down of rocks by the action of wind, water, and climate. This process is called weathering.
3.  The smaller particles of the rocks obtained due to weathering get further decomposed on long exposure to air and moisture.
4.  Finally, the decomposed parts of dead plants and animals get mixed up with soil formed by the above processes. This gives the soil enough energy in the form of organic matter.

Question 5.
How is clayey soil useful for crops?
Answer:
Clayey soil retains water to a great extent. Thus the crops which require more water grow well in clayey soil.

Question 6.
List the differences between clayey soil and sandy soil.
Answer:

Clayey Soil	Sandy Soil
1.Proportion of fine particles is large.	1.Proportion of big particles is large.
2. Has least percolation rate of water.	2. Has largest percolation rate of water.
3. Has good water holding capacity.	3. Has poor water holding capacity.

Question 7.
Sketch the cross-section of soil and label the various layers.
Answer:

Fig. A soil profile. Various horizontal zones indicate the stages in soil formation

Question 8.
Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Answer:
Given, amount of water = 200 mL
Time taken = 40 min
Rate of percolation (mL/min) = \(\frac { Amount of water(mL) }{ Amount of water(mL) }\)
= \(\frac { 200 ml}{ 40 Min }\)
= 5 mL / min .

Question 9.
Explain, how soil pollution and soil erosion could be prevented.
Answer:
Prevention of soil pollution:

1. There should be a ban on polythene bags and plastics.
2. Waste products and chemicals should be treated before they are released into the soil.
3. The use of pesticides should be minimized

Prevention of soil erosion:

1. By growing trees.
2. Avoid deforestation.
3. Maintaining the porous structure of the soil.
4. Control and reclamation of ravines and shifting of cultivation.

Question 10.
Solve the following crossword puzzle with the clues given below:

Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.
Down
1. In desert, soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.
Answer:

We hope the NCERT Solutions for Class 7 Science Chapter 9 Soil help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 9 Soil, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants.

Board	CBSE
Textbook	NCERT
Class	Class 7
Subject	Science
Chapter	Chapter 1
Chapter Name	Nutrition in Plants
Number of Questions Solved	13
Category	NCERT Solutions

NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants

Question 1.
Why do organisms need to take food?
Answer:
Organisms need to take food to

1. get the energy to do work.
2.  build up the body.
3. repair damages in the body.
4.  maintain the functions of the body.

Question 2.
Distinguish between a parasite and a saprotroph.
Answer:

Parasite	Saprotroph
1. A parasite takes the food from the organism on which it survives.	1. They secrete digestive juices on the dead and decaying matter and convert it into a solution
2. They feed on a living organism.	2. They feed on dead and decaying matter.
3. The organism on which it survives is called host.	3. They do not feed on a living organism.
4. It deprives the host of valuable nutrients.	4. There is no host at all.

 Question 3.
How would you test the presence of starch in leaves?
Answer:

1. Take two healthy green potted plants of the same kind in order to remove all the starch from the leaves.
2.  Keep one in the darkroom (or in a black box) for 72 hours and the other in the sunlight.
3.  Now, take one leaf from each of the plants.
4. Put few drops of iodine solution on each of the leaves.
5.  The leaf kept in the sunlight will turn blue-black due to the presence of starch.
6. The leaf kept in the dark will not turn blue-black because of the absence of starch.

Question 4.
Give a brief description of the process of synthesis of food in green plants.
Answer:
The leaves of a plant have a green pigment called chlorophyll. In the presence of sunlight, they use carbon dioxide and water to synthesize carbohydrates.
Carbon dioxide + Water \(\xrightarrow [ Sunlight ]{ Chlorophyll } \) Carbohydrade + Water + Oxygen
During the process, oxygen is released. The carbohydrates ultimately get converted into starch.
Carbon dioxide from the air is taken through stomata. Water and minerals are absorbed by the roots and transported to the leaves.

Question 5.
Show with the help of a sketch that plants are the ultimate source of food.
Answer:

Fig. Plants capture solar energy by a unique process called photosynthesis

Question 6.
Fill in the blanks:

1. Green plants are called …….. since they synthesize their own food.
2. The food synthesized by the plants is stored as ………
3. In photosynthesis solar energy is captured by the pigment called ……….
4. During photosynthesis plants take in ……… and release ……….

Answer:

1. autotrophs
2. starch
3. chlorophyll
4. carbon dioxide, oxygen

Question 7.
Name the following:

1. A parasitic plant with a yellow, slender, and branched stem.
2. A plant that is partially autotrophic.
3. The pores through which leave exchange gases.

Answer:

1. Cuscuta
2. Insectivorous plants
3. Stomata

Question 8.
Tick the correct answer:
(a) Amarbel is an example of:
(i) Autotroph
(ii) Parasite
(iii) Saprotroph
(iv) Host
(b) The plant which traps and feeds on insects is:
(i) Cuscuta
(ii) China rose
(iii) Pitcher plant
(iv) Rose
Answer:
(ii) Parasite
(iii) Pitcher plant

Question 9.
Match the items given in Column I with those in Column II.

Column I	Column II
Chlorophyll	Bacteria
Nitrogen	Heterotrophs
Cuscuta	Pitcher plant
Animals	Leaf
Insects	Parasite

Answer:

Column I	Column II
Chlorophyll	Leaf
Nitrogen	Bacteria
Cuscuta	Parasite
Animals	Heterotrophs
Insects	Pitcher plant

 Question 10.
Mark T if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesize their food are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Answer:
(i) F
(ii) F
(iii) T
(iv) T

Question 11.
Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair
(ii) Stomata
(iii) Leaf veins
(iv) Petals
Answer:
(ii) Stomata

Question 12.
Choose the correct option from the following:
Plants take carbon dioxide from the atmosphere mainly through their:
(i) roots
(ii) stem
(iii) flowers
(iv) leaves
Answer:
(iv) leaves

Question 13.
Why do farmers grow many fruits and vegetable crops inside large greenhouses? What are the advantages to the farmers?
Answer:
Most of the crops require a lot of nitrogen to make protein. After the harvest, the soil becomes deficient in nitrogen. Though nitrogen gas is available in the air, plants cannot use it directly. They need nitrogen in a soluble form. The bacterium called Rhizobium can take atmospheric nitrogen and convert it into soluble nitrogenous components. Rhizobium is present in the roots of some fruits and vegetables and legumes plants which provides nitrogen to them. By crop rotation, farmers increase the nitrogenous compounds in soil. So there is no need to add nitrogenous fertilizers to the soil in which leguminous plants are grown. By this practice, farmers provide good quality crops and save money.

We hope the NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants, drop a comment below and we will get back to you at the earliest.

NCERT Solutions for Class 8 Science Chapter 15 Some Natural Phenomena are part of NCERT Solutions for Class 8 Science. Here we have given NCERT Solutions for Class 8 Science Chapter 15 Some Natural Phenomena.

Board	CBSE
Textbook	NCERT
Class	Class 8
Subject	Science
Chapter	Chapter 15
Chapter Name	Some Natural Phenomena
Number of Questions Solved	12
Category	NCERT Solutions

NCERT Solutions for Class 8 Science Chapter 15 Some Natural Phenomena

NCERT TEXTBOOK EXERCISES

Select the correct option in Questions 1 and 2.

Question 1.
Which of the following cannot be changed easily by friction?
(a) A plastic scale
(b) copper rod
(c) An inflated balloon
(d) A woolen cloth.
Answer.
(b) A copper rod.

Question 2.
When a glass rod is rubbed with a piece of silk cloth the rod
(а) and the cloth both acquire a positive charge.
(b) becomes positively charged while the cloth has a negative charge.
(c) and the cloth both acquire a negative charge.
(d) becomes negatively charged while the cloth has a positive charge,
Answer.
(d) becomes negatively charged while the cloth has a positive charge.

Question 3.
Write T against true and ‘F’ against false in the following statements:
(a) Like charges attract each other. (T/F)
(b) A charged glass rod attracts a charged plastic straw. (T/F)
(c) Lightning conductor cannot protect a building from lightning. (T/F)
(d) Earthquakes can be predicted in advance. (T/F)
Answer.
(a) False
(b) True
(c) False
(d) False

Question 4.
Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.
Answer.
The crackling sound is heard because when the sweater is rubbed while taking it off, it acquires a small charge.

Question 5.
Explain why a charged body loses its charge if we touch it with our hand.
Answer.
When we touch a charged body the total charge is transferred into the earth through our body and it loses its charge.

Question 6.
Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?
Answer.
The destructive energy of an earthquake is measured on a scale called the Richter scale. An earthquake that measures 3 on the Richter scale Will be recorded by a seismograph. However, it is not likely to cause much damage.

Question 7.
Suggest three measures to protect ourselves from lightning.
Answer.

1. We should not use TV or cable phone during lightning.
2. After hearing the last thunder, wait for at least 30 minutes before coming out of the safe place.
3. A house or a building is a safe place. If you are travelling by car or by bus, you are safe inside with the windows and doors of the vehicle shut.

Question 8.
Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
Answer.
A charged balloon is repelled by another charged balloon because both have the same charge. And we know similar charges repel each other. But a charged balloon attracts an uncharged balloon and loses its own charge to the other balloon.

Question 9.
Describe with the help of a diagram an instrument which can be used to detect a charged body.
Answer.
Electroscope: An electroscope is a device used to detect the presence of charge of an object.
Principle: It works on the principle that like charges repel while unlike charges attract each other.

Structure and Working: An electroscope has a metal rod with a thin metal strip or leaf attached to it at the bottom. At the top, the rod enters into a cup. The bottom part of the rod and leaf is enclosed in a glass box for protection. When the knob of the electroscope is touched with a charged ebonite or glass rod, the leaves open out or diverge. The extent of divergence depends upon the amount of charge on the electroscope.

Question 10.
List three states in India where earthquakes are more likely to strike.
Answer.
The states that fall in seismic zones are more earthquake-prone. Jammu and Kashmir, Himachal Pradesh, and Gujarat are a few such states.

Question 11.
Suppose you are outside your home and an earthquake strikes. What precautions would you take to protect yourself?
Answer.

1. Find a safe place, that will be away from buildings, trees and overhead power lines. Do not be on the ground but squat low on it to make yourself the smallest target to be struck.
2. If we are in a car or a bus, we should not come out, as the driver needs to drive slowly to a clear spot. Do not come out till the earthquake stops.

Question 12.
The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.
Answer.
No, I would not carry an umbrella. Because the pointed rod of the umbrella can become a target of lightning.

We hope the NCERT Solutions for Class 8 Science Chapter 15 Some Natural Phenomena help you. If you have any query regarding NCERT Solutions for Class 8 Science Chapter 15 Some Natural Phenomena, drop a comment below and we will get back to you at the earliest.

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.

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.
   

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).

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 7 Science Chapter 8 Winds, Storms and Cyclones are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 8 Winds, Storms and Cyclones.

Board	CBSE
Textbook	NCERT
Class	Class 7
Subject	Science
Chapter	Chapter 8
Chapter Name	Winds, Storms and Cyclones
Number of Questions Solved	9
Category	NCERT Solutions

NCERT Solutions for Class 7 Science Chapter 8 Winds, Storms and Cyclones

Question 1.
Fill the missing word in the blank spaces in the following statements :

1. The wind is ……… air.
2. Winds are generated due to ……….. heating on the earth.
3. Near the earth’s surface …………. air rises up whereas ………. air comes down.
4. Air moves from a region of ……….. pressure to a region of ……….. pressure.

Answer:

1. moving
2. uneven
3. warm, comparatively cooler
4. high air, low air

Question 2.
Suggest two methods to find out wind direction at a given place.
Answer:
Two methods to find out wind directions are:
(i) using weathercock (Fig.).
(ii) one simple method used by common people is to hold some dust and release in the air. Dust will fly in the direction of air.

Fig. A weathercock

Question 3.
State two experiences that made you think that air exerts pressure (other than those given in the text).
Answer:
Experiment 1: When we fill the air in a balloon it flattens due to pressure exerted by air. Also when it is overfilled with air it bursts due to excess air pressure

Fig. Air exerts pressure
Experiment 2: When we hang a banner in a place of moving fast air, it tears due to the pressure exerted by the air.

Question 4.
You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Answer:
No, a house which has no ventilators is not a safe or healthy house to live in. The air circulation is not present in such a house. So, it has no fresh air. Because warm air rises up and goes out through ventilators and fresh air comes in through windows.

Question 5.
Explain why holes are made in hanging banners and hoardings.
Answer:
We know that air exerts pressure. If there are no holes in the banners and hoardings they will be damaged. To make them safe, holes are made to give the air safe passage.

Question 6.
How will you help your neighbours in case a cyclone approaches your village/ town?
Answer:
I will help by following ways :

1. Warning everyone about the coming danger.
2.  Searching for shelter.
3. Keeping storage of water and food.
4. Setting up a first-aid facility.

Question 7.
What planning is required in advance to deal with the situation created by a cyclone?
Answer:
To deal with the situation created by a cyclone we must do the following planning in advance.
On the part of the government:

• Rapid communication of warnings to the government agencies, the ports, fishermen, ships, and to the general public must be ensured.
• There must be the construction of cyclone shelters in cyclone-prone areas and administrative arrangements for moving people fast to safer places.

On the part of the public following actions must be taken:

• keep ready the phone numbers of all emergency services like police, fire brigade, and medical centres.
• make necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc., to safer places.

Question 8.
Which one of the following places is unlikely to be affected by a cyclone?
(i) Chennai
(ii) Mangaluru (Mangalore)
(iii) Amritsar
(iv) Puri
Answer:
(iii) Amritsar

Question 9.
Which of the statements given below is correct?
(i) In winter the winds flow from the land to the ocean.
(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.
Answer:
(i) In winter the winds flow from the land to the ocean.

We hope the NCERT Solutions for Class 7 Science Chapter 8 Winds, Storms and Cyclones help you. If you have any query regarding NCERT Solutions for Class 7 Science Chapter 8 Winds, Storms and Cyclones, drop a comment below and we will get back to you at the earliest.

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.

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

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.

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 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.

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