Question

Which one of the following is an example for disproportionation reaction ?

• A. $A{g}^{2+}\left(aq\right)+Ag\left(s\right)\to 2A{g}^{+}\left(aq\right)$
• B. $P_4\left(s\right)+3O{H}^{-}\left(aq\right)+3H_{2}O\to P{H}_3\left(g\right)+3{H_{2}P{O}_2}^{-}\left(aq\right)$
• C. $S\left(s\right)+O_2\left(g\right)\to S{O}_2\left(g\right)$
• D. $Zn\left(s\right)+CuS{O}_4\left(aq\right)\to ZnS{O}_4\left(aq\right)+Cu\left(s\right)$

Answer 1

Answer: (B)

$P_4\left(s\right)+3O{H}^{-}\left(aq\right)+3H_{2}O\to P{H}_3\left(g\right)+3{H_{2}P{O}_2}^{-}\left(aq\right)$

Disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states.

$\underset{0}{P_4\left(s\right)}+3O{H}^{-}\left(aq\right)+3H_{2}O\to \underset{-3}{P{H}_3\left(g\right)}+\underset{+1}{3H_{2}P{O}_2^{-}\left(aq\right)}$

This reaction involves simultaneous oxidation and reduction of $P$ atom.

Hence, option $B$ is correct.