Which of the following reacts with phenol to give salicylaldehyde after hydrolysis?

The product obtained is/are

The major product of the following reaction sequence is:
Aniline $\xrightarrow[(i) NaNO_2, HCl, 273-278K]{(ii) H_2O, warm} \text{Product}$ $\xrightarrow[(iv) NaOH]{(iii) Br_2, (excess)} \text{Product}$ $\xrightarrow{(v) CH_3I} \text{Final Product}$

What are $X$ and $Y$ in the following reactions?

The acidic property of phenol is due to which of the following?

Which of the following compounds is most readily nitrated?