The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is

Step-by-step solution

Methionine is the only amino acid among the given options that contains sulphur. During sodium fusion, an organic compound containing both nitrogen and sulphur forms sodium thiocyanate ( NaSCN ). This extract gives a blood-red colour when treated with Fe³⁺ ions due to the formation of ferric thiocyanate, [Fe(SCN)]²⁺ . Although the question mentions sodium nitroprusside (which typically yields a violet colour with sulphide ions), the blood-red colour specifically confirms the presence of both nitrogen and sulphur. T