JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Practical and Analytical Chemistry

Reagent, 1-naphthylamine and sulphanilic acid in acetic acid is used for the detection of :

(A)NO
(B) $N_{2} O$
(C) $NO_{2}^{-}$ ✓ Correct
(D) $NO_{3}^{-}$

Answer: (C)

Solution

In acetic acid the nitrite ion is converted to nitrous acid, which diazotises sulphanilic acid. The diazonium salt so formed couples with 1-naphthylamine to give a red azo dye, and this red colour is the Griess test. The reagent therefore detects the nitrite ion

N O_{2}^{-}

JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Single correct option

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