When benzene diazonium chloride reacts with phenol to form product ' $\mathrm{X}$ '. In this ' $\mathrm{X}$ ' how many ${\mathrm{sp}}^2$ hybridised carbon atoms are present?

Benzene diazonium chloride reacts with phenol to form an azo bond containing compound known as p-hydroxy azobenzene. This reaction occurs in a mild basic condition.

So, X is p-hydroxy azobenzene.

Each carbon atom of benzene is ${\mathrm{sp}}^2$ hybridised.

Thus, there are total $12{\mathrm{sp}}^2$ hybridised carbon atoms in X. Hence, the correct answer is 12 .