Question

Explain the differences between pure air and polluted air.

Answer 1

In pure air, the constituents Oxygen, Nitrogen and other gases are present in 20.95%, 78.09% and 0.96% respectively.
But in polluted air the presence of these gases varies a lot.
And may have a greater percent of harmful and toxic gases.
If the percentage of Oxygen is greater than 21% than it is also harmful and less than 20% is also harmful and same is true with respect to other gases.