Question:
Demonstrate through a simple experiment that the air mainly contains nitrogen and oxygen in the volume ratio of 4: 1.
Answer:
Aim of experiment: To show that air contains nitrogen and oxygen in the ratio 4 : 1 by volume:
Procedure: Take a glass container and fix a candle at its centre. Put some quantity of water in the container. Place an empty, dry gas jar over it. Mark five marks above water surface on the jar at equal distances shown in the figure given below.
The candle is lightened and is covered with the gas jar. After some time the candle is extinguished and the water level is raised in gas jar. The raised level in water is 1 / 5 of the volume of air in the gas jar.
This proves that one part of the air of the jar is a gas which supports combustion, i.e., oxygen. Hence, 1/5 by volume is oxygen in air.
Air Around Us
Q 1.
What happens if the percentage of carbon-dioxide increases in the air?
Q 2.
What is the source of oxygen gas in air?
Q 3.
Name the main component of air.
Q 4.
What is the percentage of nitrogen in air?
Q 5.
The component of air used by green plants to make their food, is………………….
Q 6.
What is the source of carbon dioxide in air?
Q 7.
Why does a lump of cotton wool shrink in water?
Q 8.
What is the composition of air?
Q 9.
The layer of air around the earth is known as………………….
Q 10.
What is wind energy? Mention its two advantages.
Q 11.
Name the main component of air.
Q 12.
Mention two uses of air.
Q 13.
How will you prove that soil contains air in it?
Q 14.
Name the major gas present in the (a) inhaled air (b) exhaled air.
Q 15.
Why is air considered as a mixture?
Q 16.
Write the necessary conditions for rusting of iron to take place.
Q 17.
What is the percentage of oxygen in air?
Q 18.
Air is a mixture. Prove this statement.
Q 19.
Describe balance of oxygen in the air.
Q 20.
Which gas in the atmosphere is essential for respiration?
Q 21.
Explain why mountaineers carry oxygen cylinders with them?
Q 22.
Name a device which uses wind energy to generate electricity.
Q 23.
You must have seen during rainy season, when it rains the animals like earthworm, snakes, snails etc. are commonly seen. Explain why?
Q 24.
Name a device which uses wind energy to generate electricity.
Q 25.
Why do we see the sky and air clear and clean after rainfall?
Q 26.
How do plants and animals help each other in exchange of gases in the atmosphere?
Q 27.
What happens if the percentage of oxygen in the air reaches to 70%?
Q 28.
Name the main component of air.
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?
