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

An example of a disproportionation reaction is

Which species among the following does not show disproportionation reactions?

The reaction $H_3PO_2 \xrightarrow{\Delta} (X) + PH_3$ is a:

In the reaction $P_4 + 3KOH + 3H_2O \to PH_3 + 3KH_2PO_2$,phosphorus is .........

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?