Identify compound $(A)$ in the following reaction:

What are $X$ and $Y$ in the following reaction sequence ?
$C_6H_5N_2^+Cl^{-}$ $\xrightarrow{X} C_6H_5CN$ $\xrightarrow[\text{(ii) } H_2O]{\text{(i) } CH_3MgBr} Y$

The conversion,$PhCN \to PhCOCH_3$,can be achieved most conveniently by reaction with

Benzonitrile on reduction with stannous chloride $(SnCl_2)$ in the presence of hydrochloric acid $(HCl)$ followed by acid hydrolysis forms,

Identify the product obtained when a Grignard reagent $(R'MgX)$ reacts with an alkyl cyanide $(RCN)$ followed by acid hydrolysis.

Identify $P$ and $R$ in the given reaction sequence:
$Toluene$ $\xrightarrow[(2) H_3O^+]{(1) CrO_2Cl_2} P$ $\xrightarrow{R} Benzoic \ acid$