Which of the following acids does not have a $-COOH$ group?

The reaction is given as: $X \xrightarrow{Y} \text{Benzoquinone}$. Identify $X$ and $Y$ in the above reaction.

Identify the reactant $x$ in the following chemical reaction:
$Phenol + (x) \xrightarrow[(2) H^+]{(1) NaOH} Salicylaldehyde$

Suppose the following reaction:
Benzene $(C_6H_6) + CH_3-CH=CH_2$ $\xrightarrow{H^{\oplus}} A$ $\xrightarrow{O_2} B$ $\xrightarrow{H^{\oplus} / \Delta} C + CH_3-CO-CH_3$
The structure of intermediate compound $B$ will be

The major product of the following reaction sequence is:
$C_6H_5OH \xrightarrow[(ii) NaOH, (iii) H^+]{(i) CHCl_3, NaOH(aq)} ?$

The order of melting point of ortho-,meta-,and para-nitrophenol is