Which one of the following species is stable in aqueous solution ?

Options

A. `Cr^(2+)`
B. `MnO_(4)^(2-)`
C. `MnO_(4)^(3-)`
D. `Cu^(+)`

Answer

B

Explanation

In `MnO_(4)^(2-)` manganese is in + 6 oxidation state which is having highest stability .
`MnO_(4)^(2-)` disproptionates in nerutal or acidic solution.
`3 MnO_(4)^(2-) + 4H^(+) rarr 2MnO_(4)^(2) + MnO_(2) + 2H_(2)O`