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

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

Garima observed that when she left her tightly capped bottle full of water in the open sunlight, tiny bubbles were formed all around inside the bottle. Help Garima to know why it so happened?

Observe the picture given in Fig. 15.1 carefully and answer the following questions

(a) What is covering the nose and mouth of the police man?

(b) Why is he putting a cover on his nose?

(c) Can you comment on air quality of the place shown in the Fig.15.1?

A list of words is given in a box. Use appropriate words to fill up the blanks in the following statements

Air, oxygen, wind, water vapour, mixture, combination, direction, road, bottles, cylinders.

(a) The ______ makes the windmill rotate.

(b) Air is a ______ of some gases.

(c) A weather cock shows the ______ in which the air is moving at that place.

(d) Mountaineers carry oxygen ______ with them, while climbing high mountains.

Make sentences using the given set of words.

(a) 99%, oxygen, nitrogen, air, together

(b) Respiration, dissolved, animals, air, aquatic

(c) Air, wind, motion, called

In a number of musical instruments, air plays an important role. Can you name some such instruments?

Explain the following observations very briefly

(a) A firki does not rotate in a closed area.

(b) The arrow of weather cock points towards a particular direction at a particular moment.

(c) An empty glass, in fact, is not empty.

(d) Breathing through the mouth may harm you.

Match the items of Column I with the items of Column II

State whether the following statements are true or false. If false, correct them.

(a) Plants consume oxygen for respiration.

(b) Plants produce oxygen during the process of making their own food.

(c) Air helps in the movements of sailing yachts and glider but plays no role in the flight of birds and aeroplanes.

(d) Air does not occupy any space.

On a Sunday morning, Paheli’s friend visited her home. She wanted to see some flowering plants in the nearby garden. Both of them went into the garden. While returning from the garden they also observed some flowering plants on the road side. But to their surprise, they found that the leaves and flowers of these roadside plants were comparatively very dull. Can you help them to know why?