Identify the oxidation states of Mn when `MnO_3^(3-)` ion undergoes disproportionation reaction under acidic medium

Options

A. `+2, +7`
B. `+2, +5`
C. `+4, +4`
D. `+7, +4`

Answer

D

Explanation

The disproportionation reaction for `MnO_(4)^(2-)` occurs as follows :
`overset(+6)(3MnO_(4)^(2-))+4H^(+) rarr overset(+4)(MnO_(2))+overset(+7)(2MnO_(4)^(-))+2H_(3)O`
Hence, `MnO_(4)^(2-)` is oxidation to `MnO_(4)^(-)` and reduced to `MnO_(2)`. Thus, oxidation state of `Mn` when `MnO_(4)^(2-)` undergoes disproportionation reaction under acidic medium are +7 and +4.
`:.` Hence option (d) is the correct answer.