When mercury $(II)$ chloride is treated with excess of $SnCl_2$,the products obtained are

$KMnO_4$ acts as an oxidising agent in acidic medium. $X$ is the difference between the oxidation states of $Mn$ in reactant and product. $Y$ is the number of $d$ electrons present in the brown red precipitate formed at the end of the acetate ion test with neutral ferric chloride. The value of $X+Y$ is $.........$

Aqueous sulphite reacts with dilute sulphuric acid to form $X_{(g)}$. The liberated $X_{(g)}$ is passed into acidified $KMnO_4$ solution. What is the oxidation state of $Mn$ in the product formed?

Match the reactions in Column $I$ with the nature of the reactions/type of the products in Column $II$.

Column $I$	Column $II$
$A$. $O_2^{-} \rightarrow O_2 + O_2^{2-}$	$p$. redox reaction
$B$. $CrO_4^{2-} + H^{+} \rightarrow$	$q$. one of the products has trigonal planar structure
$C$. $MnO_4^{-} + NO_2^{-} + H^{+} \rightarrow$	$r$. dimeric bridged tetrahedral metal ion
$D$. $NO_3^{-} + H_2SO_4 + Fe^{2+} \rightarrow$	$s$. disproportionation

Which of the following changes does not occur when $K_2Cr_2O_7$ reacts with $H_2O_2$ solution?

Assign $A, B, C, D$ from the given type of reaction.
$Na_2SO_3 + BaCl_2 \longrightarrow BaSO_3 \downarrow + 2NaCl$