Explanation

(a)
Carbylamine reaction is given by aliphatic and aromatic primary amine hence, it can be used for the distinguish of primary amine with secondary and tertiary amine. In this reaction, a primary amine reacts with chloroform and alcoholic KOH to give poisonous substance isocyanide.
$RNH_{2} + CHCI_{3} + 3KOH(alc.)\overset{\mathrm{\Delta}}{\rightarrow}RNC + 3KCI + 3H_{2}O$
Primary amine alkyl isocyanide