Question:
Describe balance of oxygen in the air.
Answer:
The oxygen in air is used by the organisms present in air, water or soil or on earth for their respiration. During respiration carbon dioxide gas is released to air. But green plants during photosynthesis use carbon dioxide of air for preparing food and they release oxygen gas in the air. Thus the balance of oxygen in air is maintained.
Air Around Us
Q 1.
What is the source of oxygen gas in air?
Q 2.
The component of air used by green plants to make their food, is………………….
Q 3.
What is wind energy? Mention its two advantages.
Q 4.
Why is air considered as a mixture?
Q 5.
Mention two uses of air.
Q 6.
Why does a lump of cotton wool shrink in water?
Q 7.
What is the percentage of nitrogen in air?
Q 8.
The layer of air around the earth is known as………………….
Q 9.
What is the source of carbon dioxide in air?
Q 10.
What is the composition of air?
Q 11.
What happens if the percentage of carbon-dioxide increases in the air?
Q 12.
How will you prove that soil contains air in it?
Q 13.
Write the necessary conditions for rusting of iron to take place.
Q 14.
Name the major gas present in the (a) inhaled air (b) exhaled air.
Q 15.
What is the percentage of oxygen in air?
Q 16.
Name the main component of air.
Q 17.
Name the main component of air.
Q 18.
Describe balance of oxygen in the air.
Q 19.
Air is a mixture. Prove this statement.
Q 20.
Explain why mountaineers carry oxygen cylinders with them?
Q 21.
Name a device which uses wind energy to generate electricity.
Q 22.
Name a device which uses wind energy to generate electricity.
Q 23.
Which gas in the atmosphere is essential for respiration?
Q 24.
Why do we see the sky and air clear and clean after rainfall?
Q 25.
How do plants and animals help each other in exchange of gases in the atmosphere?
Q 26.
Name the main component of air.
Q 27.
What happens if the percentage of oxygen in the air reaches to 70%?
Q 28.
You must have seen during rainy season, when it rains the animals like earthworm, snakes, snails etc. are commonly seen. Explain why?
Q 29.
What is wind energy? Mention its two advantages.
Q 30.
List five activities that are possible due to presence of air.
Q 31.
Mention one necessary condition for the combustion to take place.
Q 32.
Explain why during an incident of fire, one is advised to wrap a woollen blanket over a burning object.
Q 33.
Demonstrate through a simple experiment that the air mainly contains nitrogen and oxygen in the volume ratio of 4: 1.
Q 34.
Why is carbon-dioxide gas used to extinguish fire?
Q 35.
How will you show that air is dissolved in water?
Q 36.
What is air? Name the major constituents of air. Also give their volume proportions in air.
Q 37.
How will you show that air supports burning?
