Sodium extract is heated with concentrated HNO3 before testing for halogens because :

Question

$\begin{array}{1 1} \text{(1) Silver halides are totally insoluble in nitric acid.} \\ \text{(2) $Ag_2$ and $AgCN$ are soluble in acidic medium.} \\ \text{(3) $S^{2−}$ and $CN^{−}$, if present, are decomposed by $conc. HNO_3$ and hence do not interfere in the test.} \\ \text{(4) Ag reacts faster with halides in acidic medium.} \end{array} $