Explanation

(b)
$CH_{3}NH_{2} + CHCI_{3} + 3KOH \rightarrow CH_{3}NC + 3KCI + 3H_{2}O$
$CH_{3}NC$ or $CH_{3} - N^{+} \equiv C^{-}$methyl isocyanide or methyl carbylamine.
This reaction is an example of carbylamine reaction and it is used for the distinction of p-amines from s- and t-amines or identification of p-amino group.