Question

Which of the following is disproportionation reaction?

• A. $C{H}_4+2O_2\to C{O}_2+2H_{2}O$
• B. $2N{O}_2+2O{H}^{-}\to N{O}_2^{-}+N{O}_3^{-}+H_{2}O$
• C. $C{H}_4+4C{l}_2\to CC{l}_4+4HCl$
• D. $2F_2+2O{H}^{–}\to 2F^{–}+O{F}_2+H_{2}O$

Answer 1

The correct option is B $2N{O}_2+2O{H}^{-}\to N{O}_2^{-}+N{O}_3^{-}+H_{2}O$

Reactions in which the same substance is oxidised as well as reduced are called disproportionation reactions.
Thus, in reaction (d), N is both oxidised as well as reduced since the oxidation number of N increases from +4 in $N{O}_2$ to +5 in $N{O}_3^{-}$ and decreases from +4 in $N{O}_2$ to +3 in $N{O}_2^{-}$.
In all other option, no substance undergoes both oxidation and reduction.
Hence, option (d) is the correct answer.