Question

Nitrogen is inert because:
A.It supports combustion
B.Of low boiling point
C.Of high electronegativity
D.Dissociation energy of its molecule is fairly high.

Answer 1

Hint: We know that nitrogen belongs to group-15 and is the first member of the family. It has an electronic configuration of $1s^{2}2s^{2}2p^3$. We say a substance is chemically inert when it is not chemically reactive. Noble gases are chemically inert because of their completely filled orbitals, but they have very little tendency to donate or accept electrons.

Complete answer:
We have to know that under ordinary conditions, molecular nitrogen is an inert gas, and it exists as a diatomic molecule. The formula of diatomic nitrogen molecules is $N_2$. We can draw the structure of $N_2$ as,
$\text{N}\equiv \text{N}$
Structure drawn using chemdraw
We can see the presence of a triple bond between two molecules of nitrogen atoms. The triple bond is covalent in nature and it is non-reactive in normal conditions.
The triple bond present in nitrogen is very strong. Therefore, it requires a lot of energy to break those bonds to take part in a reaction. Hence, nitrogen is commonly referred to as and used as an inert gas. Dissociation energy of this molecule is fairly high.
We can also say nitrogen is inert due to its p-subshell is half-filled because of its maximum exchange energy. Thus, it exists in stable form like inert gas and it forms a triple bond. Molecules of nitrogen are very stable and its dissociation energy is $$225kcal/mol$$.
$\therefore$ Option (D) is correct.

Note:
Nitrogen gas reacts with alkali metal like lithium to form lithium nitride. The formula of lithium nitride is $L{i}_{3}N$. Under high temperatures and pressure, nitrogen reacts with hydrogen to form ammonia. This is known as the Haber process. We use an inert atmosphere of gases such as nitrogen, argon (or) helium in several chambers for chemical reactions, and in storage containers for water-sensitive/oxygen-sensitive to avoid unnecessary reactions of substances with water (or) oxygen.