NCERT Book Class 6 Science Air Around us

Air Around us

We have learnt in Chapter 9 that all living things require air. But, have you ever seen air? You might not have seen air, but, surely you must have felt its presence in so many ways. You notice it when the leaves of the trees rustle or the clothes hanging on a clothes-line sway. Page  of an open book begin fluttering when the fan is switched on. The moving air makes it possible for you to fly your kite. Do you remember Activity 3 in Chapter 5 in which you separated the sand and sawdust by winnowing? Winnowing is more effective in moving air. You may have noticed that during storms the wind blows at a very high speed. It may even uproot trees and blow off the rooftops. Have you ever played with a firki

WHAT IS AIR MADE UP OF?

Until the eighteenth century, people thought that air was just one substance. Experiments have proved that it is really not so. Air is a mixture of many gases. What kind of a mixture is it? Let us find out about some of the major components of this mixture, one by one. Water vapour We have learnt earlier that air contains water vapour. We also saw that, when air comes in contact with a cool surface, it condenses and drops of water appear on the cooled surfaces. The presence of water vapour in air is important for the water cycle in nature. 

Carbon dioxide

In a closed room, if there is some material that is burning, you may have felt suffocation. This is due to excess of carbon dioxide that may be accumulating in the room, as the burning continues. Carbon dioxide makes up a small component of the air around us. Plants and animals consume oxygen for respiration and produce carbon dioxide. Plant and animal matter on burning, also consumes oxygen and produces mainly carbon dioxide and a few other gases.

Dust and smoke

The burning of fuel also produces smoke. Smoke contains a few gases and fine dust particles and is often harmful. That is why you see long chimneys in factories. This takes the harmful smoke and gases away from our noses, but, brings it closer to the birds flying up in the sky! Dust particles are always present in air.

Exercises

1. What is the composition of air?

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

3. How will you prove that air supports burning?

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

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

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

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

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

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

Please refer to attached file for NCERT Class 6 Science Air Around us