KCET 2025 Chemistry Paper

The only reagent that will "pick out" a primary aromatic amine (aniline) but not a secondary one (N-methylaniline) is the carbylamine test:
- Carbylamine test (Option D: CHCl3+ alcoholic KOH )
−RNH2+CHCl3+3‌KOH⟶R−NC (isocyanide, foul smell) +3‌KCl+3H2O
- Only primary amines give the isocyanide; secondary amines (like N-methylaniline) do not react.
Options A,B and C all react (or fail to react) with both aniline and N -methylaniline in essentially the same way, so they cannot be used to tell the two apart.