Lassaigne's test is used for the detection of which of the following

Lassaigne’s test is used for the detection of which of the following elements?

N, S, P, Cl

C, N, P, Br

C, N, S, I

C, N, S, Br

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC Geoscientist – 2023

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Lassaigne’s test is a qualitative test used in organic chemistry to detect the presence of elements like Nitrogen (N), Sulfur (S), Halogens (Chlorine, Bromine, Iodine – Cl, Br, I), and Phosphorus (P) in an organic compound. The test involves fusing the organic compound with metallic sodium, which converts these elements into ionic compounds (NaCN, Na₂S, NaX, Na₃P) that can be detected by specific tests in the aqueous extract (Lassaigne’s extract). Option A correctly lists Nitrogen, Sulfur, Phosphorus, and Chlorine, all of which are detectable by Lassaigne’s test.

Lassaigne’s test detects elements *other than* carbon and hydrogen present in organic compounds.

After fusion with sodium, the compound is plunged into distilled water and boiled to create the Lassaigne’s extract. This extract is then tested for specific ions: CN⁻ (for N), S²⁻ (for S), X⁻ (for halogens), and PO₄³⁻ (for P). Carbon and hydrogen are the primary constituents of organic compounds and are not typically detected by this method.

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