$Cu^{+}$ ion is not stable in aqueous solution,because it shows $-$

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

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$P_4 + 3NaOH + 3H_2O \longrightarrow PH_3 + 3NaH_2PO_2$
(Note: The reaction provided is the standard balanced equation for the disproportionation of white phosphorus.)

In the following reaction,$3Br_2 + 6CO_3^{2-} + 3H_2O \rightarrow 5Br^{-} + BrO_3^- + 6HCO_3^-$,what happens to bromine?

Which one of the following does not undergo disproportionation reaction?

Refer to the periodic table and answer the following questions:
$(a)$ Select the possible non-metals that can show disproportionation reaction.
$(b)$ Select three metals that can show disproportionation reaction.