Neutral ferric chloride is added to the aqueous solution of acetate. $A$ blood-red colour is obtained; this is due to the formation of which compound?

$X$ (salt) + $AgNO_3$ $(aq.) \to \underset{(\text{Yellow ppt.})}{Y \downarrow}$ (soluble in excess of $NH_3$ solution). Salt $X$ does not contain:

Assign $A, B, C, D$ from the given type of reaction.
$BaSO_4 \downarrow + dil. HCl$ $(Excess)$ $\longrightarrow$ No reaction

$A$ white precipitate was formed when $BaCl_{2}$ was added to the water extract of an inorganic salt. Further,a gas $X$ with a characteristic odour was released when the formed white precipitate was dissolved in dilute $HCl$. The anion present in the inorganic salt is ..... .

White heavy precipitates are formed when $BaCl_2$ is added to a clear solution of compound $A$. Precipitates are insoluble in dilute $HCl$. Then,the compound $A$ is

$S^{2-}$ and $SO_3^{2-}$ can be distinguished by using