In the given esterification reaction,the labelled $^{18}O$ will be found in:

An organic compound $A$ $(C_{6}H_{6}O)$ gives a dark green coloration with ferric chloride. On treatment with $CHCl_{3}$ and $KOH$,followed by acidification,it gives compound $B$. Compound $B$ can also be obtained from compound $C$ on reaction with pyridinium chlorochromate $(PCC)$. Identify $A, B$ and $C$.

Phenol can be converted into salicylic acid by heating with

Identify the reagents $X$,$Y$,and $Z$ in the following reaction schemes:
$(i)$ Benzene $\xrightarrow{X}$ Benzenesulfonic acid $\xrightarrow{Y}$ Sodium phenoxide $\xrightarrow{Z}$ Phenol
$(ii)$ Aniline $\xrightarrow{X}$ Benzenediazonium chloride $\xrightarrow{Y}$ Phenol
$(iii)$ Chlorobenzene $\xrightarrow{X}$ Sodium phenoxide $\xrightarrow{Y}$ Phenol

What will be the product $A$?

$HOOC-COOH + HO^{18}CH_2-CH_2^{18}OH \xrightarrow[H^+]{\Delta} (A)$; Product $(A)$ is: