Identify $C$ in the following reaction sequence:

Which of the following compounds is most reactive in electrophilic aromatic substitution?

Identify product $B$ in the following reaction.
Sodium phenoxide $\xrightarrow[6 \text{ atm}]{CO_2, 398 \text{ K}} A$ $\xrightarrow{H_3O^{+}} B$

Phenol can be distinguished from ethanol by the reagent

Heating benzoic acid with $X$ and phenol with $Y$ gives benzene. $X$ and $Y$ are respectively:

In the reaction sequence,phenol reacts with $HNO_2$ to form $X$,which then reacts with phenol in the presence of $H_2SO_4$ to form $Y$. Identify the major products $X$ and $Y$.