JEE Main Chemistry Class 12 Analytical Chemistry Questions

In Lassaigne's test, fusion with sodium take place and following species formed respectively.
(a) Aniline ⟶CN−
(b) Benzene sulfonic acid ⟶
(c) Thiourea ⟶S2−
Reaction of CN− with hot and acidic solution of FeSO4 lead to formation of Fe4[Fe(CN)6]3 which is blue in colour. It contains iron in both II and III oxidation state. Reaction of S2− with sodium nitroprusside
Na2S+Na2[Fe(CN)5NO]→

Na4[Fe(CN)5NOS]

(violet‌in‌colour)

Phenoxide ion on reacting with FeCl3 give red colour with FeCl3