Which of the following is a disproportional reactions ?

Options

A. `Cr_(2)O_(7)^(2-)+2overset(ө)OHrarr2CrO_(4)^(2-)+H_(2)O`
B. `CrO_(4)^(2-)+2H^(o+)rarrCr_(2)O_(2)^(2-)+H_(2)O`
C. `CaCO_(3)+2H^(o+)rarrCa^(2)+H_(2)O+CO_(2)`
D. `Cu_(2)O+2H^(o+)rarrCu+Cu^(2+)+H_(2)O`

Answer

D

Explanation

`Cu^(1+)` is changing ot `Cu` and `Cu^(2+)`, i.e., from oxidation number of `+1` to `0` and `+2`.