A compound containing C, N, S and Cl is fused with excess sodium (so no thiocyanate forms). The sodium extract is acidified with dilute $HNO X_{3}$ but is NOT boiled, and then $AgNO X_{3}$ is added. Which precipitate(s) form together with $AgCl$ ?

Answer: C

With excess sodium the extract contains

NaCN

Na X_{2} S

and

NaCl

. Without boiling,

CN X^{-}

and

S X^{2 -}

are not removed as

HCN

and

H X_{2} S

, so

Ag X^{+}

precipitates white

AgCN

and black

Ag X_{2} S

along with

AgCl

. This is why the extract is boiled with

HNO X_{3}

first.