Question

What is the most abundant gas in the earth’s atmosphere?

Answer 1

The most abundant gas in the atmosphere belongs to the p-block as is the element of group number 15 and period number 2. Its atomic number is 7 and in the gaseous form, it is in diatomic form.

Complete answer:
Gases are those substances in which the molecules are very far from each other. There are many gases present in the earth's atmosphere which are very essential for humans, plants, and animals.
The gases which are present in the earth’s atmosphere are oxygen gas, carbon dioxide gas, nitrogen gas, methane, ozone, nitrous oxide, etc.
The gas which is most abundant in the atmosphere accounts for 78% of the total volume of gas and this gas is nitrogen gas. Following this, the second most abundant gas is oxygen gas which accounts for around 21% of total volume. Others like $C{{O}_{2}}$, methane, ozone, etc account 1%.
The nitrogen gas is present as a diatomic form in the atmosphere (${{N}_{2}}$).
The diatomic form of nitrogen in the atmosphere is not used as such but the plants take the nitrogen from the atmosphere and convert it into nitrates and nitrites. Amino acids are required by the plants for their growth and these amino acids are produced by nitrates and nitrites. In the soil nitrogen-fixing bacteria is present and takes nitrogen from the atmosphere.

Note:
As we know oxygen is used for the respiration purpose by living things while carbon dioxide is a greenhouse gas which causes global warming. Both the nitrogen and oxygen gases are present in a diatomic form in the atmosphere.