Oxidation reaction involves loss of electrons, and reduction reaction involves gain of electrons. The reaction in which a species disproportinates into two oxidation states ( lower and higher) is called disproportionation reaction.
Which of the following is not a dispropotional reaction?

Options

A. `overset(ө)OH+Br_(2)rarrBr^(ө)+BrO_(3)^(ө)`
B. `Cu_(2)O+2H^(o+)rarrCu+Cu^(2+)+H_(2)O`
C. `(CN)^(ө)rarrCO_(3)^(2-)+NO_(3)^(ө)`
D. `(CN)_(2)+2overset(ө)OHrarrCN^(ө)+CNO^(ө)+H_(2)O`

Answer

C

Explanation

a. Disproportionation reaction:
`overset(0)Br_(2)rarroverset(-1)2Br^(ө)`
(Oxidation state of `Br_(2)` decreases from `0` to `-1`)
`overset(0)Br_(2)rarrBrO_(3)^(ө)`
x-6=-1`
x=5`
(Oxidation stated of `Br_(3)` increases from `0` to `+5`).
b. Disproprtionation reaction:

c. Oxidation
`overset(+2)(CN^(ө))rarroverset(+4)CO_(3)+2e^(-)`
`x-3= -1, x-6= -2`
`x=2, x=4`
`CN^(ө)rarrNO_(3)^(ө)+8e^(-)`
(Oxidation state of `N= -3`) , `x-6= -1`
`x=5`
Both are oxidation.
d. Disproportionation reaction:
`(CN)_(2)` gets simultaneously oxidised to `CNO^(ө)` (cyanate ion) and reduced to `CN^(ө)`
The oxidation number of `N` in `(CN)_(2)` is `-3`, in `CN^(ө)` is `-2`, and in `CNO^(ө)` is `-5`.