Which among the following is a dihydric phenol?

Reaction of phenol with $NaOH$ followed by heating with $CO_{2}$ under high pressure,and subsequent acidification gives compound $X$ as the major product,which can be purified by steam distillation. When reacted with acetic anhydride in the presence of a trace amount of conc. $H_{2}SO_{4}$,compound $X$ produces $Y$ as the major product. Compound $Y$ is $....$

Explain how the $-OH$ group attached to the carbon of the benzene ring activates the benzene ring for electrophilic substitution reactions.

The product obtained is/are

Identify $X$ and $Y$ in the following reaction:
$X \xrightarrow{Y} \text{Benzoquinone}$

When phenol reacts with dilute nitric acid at room temperature,the major product obtained is