Air around Us - Solutions

 CBSE Class–VI Subject Science

NCERT Solutions

Question 1. What is the composition of air?

Answer: Various components of air are:

(a) Nitrogen - 78.11%
(b) Oxygen - 20.95%
(c) Carbon dioxide - 0.03%
(d) Other gases
(e) Water vapour
(f) Dust particles

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

Question 3. How will you prove that air support burning?
 Step I: Two shallow containers are taken and burning candles are fitted into it.

Step II: Now, water is filled in the container at two different levels.

Step III: Both the candles are then covered with glass.

Step IV: After sometimes, we observed that the candles having less water in its container lights off.

This happened because the container having more water contains more oxygen and therefore it burnt for more time.

Thus, it is proved that air supports burning.

Question 4. How will you show that air is dissolved in water?
Answer: When a tumbler containing water is heated, tiny bubbles appear on the inner side. These bubbles appear before the water starts boiling. So, these must be air bubbles. This shows that water contain air.

Question 5. Why does a lump of cotton wool shrink in water?
 A lump of cotton wool shrinks in water because the air inside wool cotton is driven out by water. The layers stick together and hence lump shrinks.

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

Question 7. 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: Five activities that are possible due to the presence of air:

(i) Helps in seed dispersal and pollination.
(ii) Sailing of ships.
(iii) Flying of the birds and kites.
(iv) Gives us oxygen to respire.
(v) Helps in the rotation of windmill.

Question 9. How do plants and animals help each other in exchange of gases in the atmosphere?
In photosynthesis, plants take carbon dioxide and give out oxygen. The animals breath in oxygen in respiration and carbon dioxide is given out which is again used by plants for photosynthesis, that is, preparation of food by plants.

This is how plants and animals help each other in the exchange of gases in the atmosphere.