NCERT Solutions Class 6 Science Chapter 15 Air Around Us

Question.1

What is the composition of air?

Answer.

Air is a mixture of nitrogen, oxygen, small amount of carbon dioxide, water vapour and some other gases. Nitrogen constitutes 78% of the air. Oxygen

constitutes 21% of the air. Carbon dioxide, water vapour and other gases constitute only 1% of the air.

Question.2

Which gas in the atmosphere is essential for respiration?

Answer.

Oxygen is essential for respiration

Question.3

How will you prove that air supports burning?

Answer.

To prove that air supports burning, we will perform an activity.

To perform this activity, things required are candle, water, container and matchbox.

First of all take a container and fix a candle in the middle of the container. Fill the container with some water. Now, light the candle and container. then cover it with an inverted container

After some time, it is observed that candle extinguishes. Candle extinguishes because the amount of air is limited inside the inverted container. Hence,

supply of oxygen is also limited. Once oxygen is completely consumed, the candle blows off. This proves that oxygen is essential for burning.

Question.4

How will you show that air is dissolved in water?

Answer.

To show that air is dissolved in water, take some water in a pan and heat it slowly. Just before the water begins to boil, look carefully at the bottom of

the pan. Tiny air bubbles are seen at the bottom of the pan before the water actually boils. These air bubbles come from the air dissolved in water. When

we heat the water, air dissolved in it escapes.

Question.5

Why does a lump of cotton wool shrink in water?

Answer.

A lump of cotton wool shrinks in water because when it is immersed in water, air present in it escapes and it reduces in size.

Question.6

The layer of air around the earth is known as _____.

Answer.

The layer of air around the earth is known as atmosphere.

Question.7

The component of air used by green plants to make their food, is _______.

Answer.

The component of air used by green plants to make their food, is carbon dioxide.

 

Question.8

List five activities that are possible due to the presence of air.

Answer.

Activities that are possible due to the presence of air are:

1. Photosynthesis
2. Respiration
3. Flight of birds, bats and insects
4. Movement of sailing yachts, gliders, parachutes and aeroplanes
5. Generation of electricity by windmill

Question.9

How do plants and animals help each other in the exchange of gases in the atmosphere?

Answer.

During photosynthesis plants take carbon dioxide from atmosphere and make their own food and oxygen is produced in this process. Plants also

consume oxygen during respiration but amount of oxygen released during photosynthesis is more than the amount of oxygen used during respiration.

Animals inhale oxygen produced by plants and in turn, carbon dioxide is produced.

In this way, plants and animals help each other in the exchange of gases in the atmosphere. 

Question. After we take a deep breath our lungs would look like
(a) a balloon without air.
(b) a balloon filled with air.
(c) a beaker filled with water.
(d) an empty beaker.

Answer : B

Question. Which of these is common to both BURNING and RESPIRATION?
(a) Both produce oxygen.
(b) Both produce carbon dioxide.
(c) Both consume energy.
(d) Both consume energy.

Answer : B

Question. Which type of pollution is caused by bursting a lot of crackers during Diwali?
(a) Water pollution
(b) Air and sound pollution
(c) Light and sound pollution
(d) Only sound pollution

Answer : B

Question. Factories usually have chimneys to :
(a) Reduce noise pollution.
(b) Reduce water pollution.
(c) Disperse harmful gases.
(d) Make the buildings more beautiful.

Answer : C

Question. Sponge is a porous material. What will happen when a piece of sponge is lowered quickly in water and squeezed under water?
(a) The sponge will become hard.
(b) The sponge will not get wet.
(c) The air trapped in the pores will rush out and bubbles will be seen in the water
(d) The sponge will dissolve in water.

Answer : C

Question. Which of the following infections is caused by a virus?
(a) Typhoid
(b) Malaria
(c) Jaundice
(d) Polio

Answer : D

Question. The figure given alongside gives the approximate break up of the waste from a household. If paper and cardboard, glass, metals and plastics can be recycled and the others cannot . Which graph BEST represents this waste distribution?

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

Answer : B

Question. Neeta, Usha and Ganesh make lists as follows:
Neeta's list : Insects that have 4 stages in their life cycle . 
Usha's list : Insects that spread diseases Ganesh's list : Animals that spread diseases through contaminated food and water . Which of the following animals would be in all their lists?
(a) Rats
(b) Mosquito
(c) Housefly
(d) No animal can be in all the lists

Answer : C

Question. Using a bicycle to go to school is a way to
(a) recycle materials.
(b) reduce pollution.
(c) reuse natural resources.
(d) reduce garbage.

Answer : B

Question. The city authorities requested the citizens to have two separate dustbins for the waste generated in their homes as shown below. What is the most likely basis on which the authorities have made this classification?

(a) The good or bad smell of waste 
(b) The bio-degradable or non-bio-degradable nature of waste
(c) The size of the waste items
(d) There is no pattern or basis.

Answer : B