The carbylamine reaction is used as a test for

The correct answer is Option (1) → Primary amines

Carbylamine Reaction (Isocyanide Test):

Only primary amines (both aliphatic and aromatic) react with CHCl₃ + alcoholic KOH to give foul-smelling isocyanide (R–NC).

Reaction: R–NH₂ + CHCl₃ + 3KOH → R–NC + 3KCl + 3H₂O

Why others do not give the test:

• Secondary amines → Form no isocyanide (no reaction or different product)
• Tertiary amines → No reaction
• Aromatic primary amines (like aniline) also give this test positively

So, the carbylamine test is specific for primary amines only.