Q. The Lassaigne's extract is boiled with dil $HNO_{3}$ before testing for halogens because
A) AGCN is soluble in $HNO_{3}$
B) Silver halides are soluble in $HNO_{3}$
C) $Na_{2}S$ and $NaCN$ are decomposed by $HNO_{3}$
D) $Ag_{2}S$ is soluble in $HNO_{3}$
Explanation
(c)
$HNO_{3}$ is added to decompose $Na_{2}S$ and $NaCN$ if present
$Na_{2}S + 2HNO_{3} \rightarrow 2NaNO_{3} + H_{2}S \uparrow$
$NaCN + HNO_{3} \rightarrow NaNO_{3} + HCN \uparrow$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.