Explanation

(b)
Action of alcoholic caustic potash on chloroform and aniline forms a bad smelling compound phenyl isocyanide.
$C_{6}H_{5}NH_{2} + CHCI_{3} + 3KOH(alc.) \rightarrow C_{6}H_{5}NC + 3KCI + 3H_{2}O$
aniline chloroform phenyl isocyanide
This reaction is called carbylamine reaction and it is actually the test of primary amines.