Class 6 Science NCERT Solutions for Chapter – 15 Air Around Us

Air Around Us

Question 1.
What is composition of air ?

Answer:
Air contains 99% nitrogen and oxygen. The remaining 1 % is carbon dioxide and a few other gases, water vapour and dust particles.

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

Answer:
Oxygen gas.

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

Answer:
We light a candle and cover it with a glass. We find after some time candle is extinguished as the amount of air inside the glass is limited.

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

Answer:
We take some water in a beaker and heat it slowly on a tripod stand. We see that well before the water begins to boil, tiny bubbles of air are seen on the inside of beaker. This shows that air is dissolved in water.

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

Answer:
Air present in lump of cotton wool gets dissolved in water and hence it shrinks.

Question 6.
The layers of air around the earth is known as ?

Answer:
Atmosphere.

Question 7.
Which component of air is used by green plants to make their food ?

Answer:
Carbon dioxide.

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

Answer:

  1. We respire due to the presence of air.
  2. Fuels are able to burn due to presence of air.
  3. Air helps in the movements of sailing yachts, gliders, parachutes and aeroplanes.
  4. Birds, bats and insects can fly due to the presence of air.
  5. Air helps in the dispersal of seeds and pollen of flowers of several plants.

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

Answer:
Animals produce carbon dioxide during respiration and use oxygen whereas plants use carbon dioxide and produce oxygen during photo- synthesis. In this way plants and animals help each other in the exchange of gases in the atmosphere.

InText Questions and Answers

Activity 1

Take an empty glass bottle. Turn it, upside down.
NCERT Solutions for Class 6 Science img 51

Now, dip the open mouth of the bottle into the bucket filled with water as shown in fig. Observe the bottle.

Question 1.
Does water enter the bottle ?

Answer:
No.

Question 2.
Now tilt the bottle slightly. Does the water now enter the bottle ?

Answer:
Yes.

Question 3.
Do you see bubbles coming out of the bottle or hear any bubbles sound ?

Answer:
Yes.

Question 4.
Can you guess what was in the bottle ?

Answer:
Air was in the bottle.

Activity 2

Fix two small candles of the same size in the middle of two shallow containers. Now, fill the containers with some water. Light the candles and then cover each one of them with an inverted glass (one much taller than the other smaller) Fig. 15.2.
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Question 1.
What happens to the burning candles and the water level ?

Answer:
The burning candles goes off. The water level rises in the two glasses.

Question 2.
Do you find any difference in your observation with the two glasses of different heights ?

Answer:
Yes, water rises higher in taller glass.

Activity 3

Find a sunny room in your school/home. Close all the doors and windows with curtains pulled down to make the room dark. Now, open the door or a window facing the sun, just a little, in such a way that it allows sunlight to enter the room only through a slit. Look carefully at the incoming beam of sunlight.
NCERT Solutions for Class 6 Science img 53

Question 1.
Do you see some tiny shining particles moving in the beam of sunlight (Fig. 15.3) ? What are these particles?

Answer:
Yes, we see some tiny shining particles moving in the beam of sunlight. These are dust particles.

Question 2.
What does this activity shows ?

Answer:
This activity shows that air contains dust particles.

Activity 4

Take some water in a glass vessel or beaker. Heat it slowly on a tripod stand. Well before the water begins to boil, look carefully at the inner surface of the vessel. Do you see tiny bubbles on the inside (Fig. 15.4) ?
NCERT Solutions for Class 6 Science img 54
Answer:
Yes, we see tiny bubbles on the inside. These bubbles come from the air dissolved in water.

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