Class 6 | Science | Chapter 15 | Air Around Us | NCERT Solutions

Question 1. What is the composition of air?

Answer 1 Air is a mixture of gases namely nitrogen, oxygen, small amount of carbon dioxide, and many other gases.Nitrogen and oxygen together make up 99% of the air. The remaining 1% is constituted by carbon dioxide and a few other gases, water vapour and dust particles.

Question 2. Which gas in the atmosphere is essential for respiration?

Answer 2 Oxygen gas

Question 3. How will you prove that air supports burning?

Answer 3 Take a small candle and light it. Cover the burning candle using a glass jar. After a few minutes, the burning candle will be extinguished. This happens because the supply of air for the burning process stopped due to a glass jar and as a result of that, the burning of a candle is also stopped. This experiment proves that air supports burning.

Question 4. How will you show that air is dissolved in water?

Answer 4 Fill a glass vessel or a beaker. Heat it slowly on a tripod stand. Now look at the inner surface of the vessel before the water starts boiling, you will be able to see tiny bubbles on the inside. This happens because, on heating water, the air dissolved in the water escapes in the form of bubbles.

Question 5. Why does a lump of cotton wool shrink in water?

Answer 5 Air is present between the gaps of cotton fibers. When it is dipped, the water replaces the air from those gaps, making the cotton lump heavy and it finally shrinks as the air gaps are removed.

Question 6. The layer of air around the earth is known as ___________.

Answer 6 Atmosphere

Question 7. The component of air used by green plants to make their food, is ___________.

Answer 7 Carbon dioxide

Question 8. List five activities that are possible due to the presence of air.

Answer 8 The 5 activities that are possible due to the presence of air are:

1) Respiration

2) Photosynthesis

3) Burning of fuels

4) Generation of electricity by windmill.

5) Scattering of seeds and pollens of plants.

Question 9. How do plants and animals help each other in the exchange of gases in the
atmosphere?

Answer 9 Plants and animals respire i.e. they intake oxygen and gives out carbon dioxide in the atmosphere. Plants take carbon dioxide from the atmosphere and prepare food and return oxygen to atmosphere by the process of photosynthesis. So, in this way plants and animals help each other in the exchange of gases in the atmosphere.