In which of the following,ortho/para substitution by an electrophile is very facile?

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 $....$

The major product formed in the following reaction is:

The electrophile involved in the below reaction is:

Which of the following reagents may be used to distinguish between phenol and benzoic acid?

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