The electrolytic reduction of nitrobenzene in a strongly acidic medium produces:

Yellow dye can be prepared by a coupling reaction of benzene diazonium chloride in acidic medium with $X$. Identify $X$ from the following.

$CH_3CH_2Br$ $\xrightarrow{AgCN} A$ $\xrightarrow{H_2, Ni} B$. The final product $(B)$ is

$Ph-NC$ $\xrightarrow{LiAlH_4} A$ $\xrightarrow{NaNO_2 + HCl} B$. Identify product $B$.

The reaction of benzylamine with nitrous acid $(HNO_2)$ produces product $A$. Identify product $A$.

$A$ compound $X$ with formula $C_4H_{11}N$ reacts with $HNO_2$ to liberate nitrogen and produce compound $Y$. The compound $Y$ on treatment with $I_2 / NaOH$ produces a sodium salt of a carboxylic acid. The compound $X$ is