Question

Which of the following is not an air pollutant?
(A) ${N_2}$
(B) ${N_2}O$
(C) $NO$
(D) $CO$

Answer 1

Hint: The non-pollutant gas from the given options is a colourless, odourless and tasteless gas which is nonflammable in nature and is not involved in combustion. Generally, inert gases are fairly non-reactive gases which readily do not react with materials and hence they are not involved in spreading pollution.

Complete step by step solution:
-So generally, a greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range. On a general basis, the primary greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide and ozone.
-${N_2}$ forms about 78% of the air, but is not a greenhouse gas ${N_2}$ does not compete with Oxygen-binding to haemoglobin (like Carbon monoxide) does. It is non-polar, due to which it is not soluble in water.
-As we know the two Nitrogen atoms are bound so tightly to each other (a triple covalent bond), it does not react with (and will not oxidize) tissue, DNA, etc. So basically, because there aren’t really any ill-effects of Nitrogen production (again, the atmosphere is already mostly Nitrogen) such as contributing to warming, chemical poisoning, and because of the importance of Nitrogen in biochemistry, Nitrogen is not an air pollutant.
-Furthermore, nitrogen is not a greenhouse gas because it does not reflect the waves of heat to any significant degree. It is reasonably inert and it does not trap much of the sun’s radiation

Therefore, ${N_2}$ is not an air pollutant. Hence, option (A) is the answer.

Note: Note that both oxides of nitrogen, $NO$ and ${N_2}O$ are responsible for acid rain. So, they are a kind of pollutant. There is a requirement that the pollutant needs to be either in gaseous form or to be able to remain suspended in the air to be an air pollutant.