Question

Sodium extract is heated with concentrated $\ce{HNO_3}$ before testing for halogens because :

• A. Silver halides are totally insoluble in nitric acid.
• B. $\ce{Ag_2S}$ and $AgCN$ are soluble in acidic medium.
• C. $\ce{S^{2-}}$ and $\ce{CN^{-}}$, if present, are decomposed by conc. $\ce{HNO_3}$ and hence do not interfere in the test.
• D. Ag reacts faster with halides in acidic medium.

Answer 1

Answer: (C)

$S^{-2}$ and $CN^-$ ions if present are decomposed by conc. $HNO_3$ and hence do not interfere in the test.