How can aniline be purified?

Aromatic primary amine when treated with cold $HNO_2$ gives

In the chemical reaction $CH_3Cl$ $\xrightarrow{AgCN} (A)$ $\xrightarrow{H_2/Pd} (B)$,what is the structure of $(B)$?

The product of the following reaction is:

When primary amine is heated with $CS_2$ in presence of excess mercuric chloride,it gives isothiocyanate. This reaction is called

For reaction-$I$,the reagents are $CH_3CONH_2, KOH, Br_2$. For reaction-$II$,the reagents are $CH_3NH_2, CHCl_3, KOH$. What are the intermediates for reaction-$I$ and reaction-$II$ respectively?