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

NEET Chemistry PYQ solved by Nitish Sir 🔥 A Qualitative Analysis / Biomolecules question — test for sulfur in amino acids using sodium fusion extract (Lassaigne's test) and sodium nitroprusside. ❓ QUESTION The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is: (1) methionine (2) serine (3) leucine (4) threonine ✅ Correct answer: (1) methionine Key idea → Methionine is a sulfur-containing amino acid. Upon sodium fusion (Lassaigne's test), sulfur converts into sodium sulfide (Na2S). Treating this extract with sodium nitroprusside (Na2[Fe(CN)5NO]) yields a violet/red-blood colored complex. Serine, leucine, and threonine do not contain sulfur and give a negative test. 👨‍🏫 ABOUT NITISH SIR B.E (Hons) BITS Pilani • AIR-16 GATE 2012 • AIR-732 JEE Main 2008 • 15+ years teaching. 🎯 FREE for re-NEET aspirants → https://neetsambhav.in 🔔 SUBSCRIBE to Chemistry Forum for daily NEET Chemistry PYQs & live doubt sessions. 💬 Telegram: https://t.me/ChemistryForumNitishSir 🌐 Website: https://neetsambhav.in #NEET #NEETChemistry #Biomolecules #QualitativeAnalysis #LassaignesTest NEET chemistry, amino acids test NEET, sodium nitroprusside test, methionine sodium fusion extract, Lassaigne test sulfur, Biomolecules NEET PYQ, qualitative organic analysis, NEET chemistry PYQ solution, Nitish Sir chemistry, NEET Sambhav, Chemistry Forum