Question

Lassaigne's extract is boiled with dil $HN{O}_3$ before testing for halogens because:

• A. slver halides are soluble in $HN{O}_3$
• B. $N{a}_{2}S$ and $NaCN$ are decomposed by $HN{O}_3$
• C. $A{g}_{2}S$ is soulble in $HN{O}_3$
• D. $AgCN$ is soulble in $HN{O}_3$

Answer 1

Answer: (B)

$N{a}_{2}S$ and $NaCN$ are decomposed by $HN{O}_3$

Dilute $HN{O}_3$ is added to the sodium fusion extract {Lassaigne's extract} for the removal of ions particularly Cyanides, Carbonates and sulphides these ions also give ppt with silver nitrate ($AgN{O}_3$) solution.

Hence option B is correct.