Question

Mention two uses of air.

Answer 1

Hint: The earth’s atmosphere comprises air which is a mixture of many gases such as nitrogen, oxygen, carbon dioxide and small amounts of other gases.

Complete step by step solution
The earth’s atmosphere is composed of air. The atmosphere above the earth’s surface consists of the ozone layer that protects us from the harmful radiations that come from outer space.
It comprises about 78% of nitrogen, 21% of oxygen, 0.9% of argon, 0.04% of carbon dioxide along with small amounts of other gases.
Some of the important uses of air include

1. Sustenance of life and growth
2. Combustion
3. Maintaining Temperature
4. Supplier of Energy
5. Photosynthesis
   We will read about two of the uses in more detail
   Combustion
   Air is essential for combustion or more precisely oxygen is essential for combustion since it helps in the burning process which is used for activities such as running of vehicles, generation of heat and electricity, cooking food etc. During combustion the fuel reacts with oxygen gas to produce energy in the form of heat and light.
   During combustion, carbon atoms react with the atmospheric oxygen to produce carbon dioxide and water.
   Temperature Control
   The air maintains the temperature of the earth’s surface by circulating hot and cold air on the surface of the earth. When air gets heated, its density reduces and it rises upwards. Since cold air is denser than the hot air, it sinks towards the ground. So, while the hot air rises creating a space of low pressure, the cold air comes and occupies this space. This cold air gets heated up with time and the cycle continues. This phenomenon gives rise to winds. When the rising hot air transfers its heat into outer space, it sinks back down thereby transferring heat from hotter regions to colder regions which is known as temperature regulation, and this process of transferring heat is known as convection. If there was no atmosphere then the daytime temperatures on earth would be very high and night time temperatures would dip below freezing.

Note: The greenhouse effect which comes into play due to the greenhouse gases present in the air provides a protective layer of insulation for life on earth.