Which of the following reactions is used to obtain salicylic acid from phenol?

Which one of the following is most reactive towards electrophilic attack?

Which product is obtained when chlorobenzene is reacted with $6-8\%$ aqueous $NaOH$ at $633\,K$ temperature and $300\,bar$ pressure in the presence of an acid catalyst?

The major product of the following reaction is:

In the following compounds,the order of acidity is:
$(I)$ Phenol
$(II)$ $p$-Cresol
$(III)$ $m$-Nitrophenol
$(IV)$ $p$-Nitrophenol

Phenol $\xrightarrow{NaNO_2/H_2SO_4} B$ $\xrightarrow{H_2O} C$ $\xrightarrow{NaOH} D$. The name of the above reaction is: