JEE Main · 2023 · 01 Feb 2023 · Shift 1 · Chapter_pending

Molisch's test, in which a sugar with $\alpha$-naphthol and concentrated sulphuric acid gives a violet ring, detects carbohydrates. The biuret test, a violet colour developed with copper(II) ions in alkali, detects the peptide linkage. The carbylamine test, which forms a foul-smelling isocyanide on warming with chloroform and alcoholic potash, detects primary amines. Schiff's reagent restored to its magenta colour detects aldehydes. Thus Molisch's test goes with carbohydrate, the biuret test with peptide, the carbylamine test with primary amine, and Schiff's test with aldehyde.