What is obtained when $H_2S$ gas is passed through $Hg_2^{2+}$ solution?

The dibasic oxoacid of phosphorus on disproportionation gives two products $A$ and $B$. $A$ and $B$ are respectively

Which of the following is not a disproportionation reaction?

In the following reaction,assign the state for the underlined atom in the products of complete hydrolysis at $R.T.$:
$\underline{N_2}O_4 + H_2O \longrightarrow HNO_3 + HNO_2$

Nitrous acid was disproportionated to form water,$HNO_3$ and $X$. In another reaction,sodium nitrite was reacted with $H_2SO_4$ to form $NaHSO_4, HNO_3$,water and $Y$. What are $X$ and $Y$ respectively?

Which of the following chemical substances undergoes self-oxidation and self-reduction during the same reaction?