question_answer

The Lassaigne's extract is boiled with cone \[HN{{O}_{3}}\] while testing for halogens. By doing so it     [AIPMT (S) 2011]

A) helps in the precipitation of AgCl

B) increases the solubility product of AgCl

C) increases the concentration of \[NO_{3}^{-}\] ions

D) decomposes \[N{{a}_{2}}S\] and NaCN, if formed

Correct Answer: D

Solution :

[d] and , if present in the extract, will be decomposed to   and  by . These will escape from the solution and will not interfere with the test for halogens.