JEE Main Chemistry Question (2026) — Solution

Step-by-step solution

Neutral ferric chloride ( FeCl _3) solution gives a characteristic violet coloured complex with compounds containing a phenolic hydroxyl group. Among the given amino acids, Tyrosine contains a phenolic - OH group in its side chain. Threonine and Serine contain aliphatic - OH groups, and Cysteine contains a thiol (- SH ) group, none of which give a positive neutral FeCl _3 test. Therefore, Tyrosine will give a violet coloured complex with neutral ferric chloride solution. Answer: Tyrosine