A solution of `KMnO_(4)` on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out ?

Explanation

`KMnO_(4)` behaves differently depending on the pH of the reaction medium.
Reduction in acid medium `(pH lt 7)` :
`MnO_(4)^(-)+8H^(+)+5e rarr Mn^(2+)("colourless")+4H_(2)O`.
Reduction in neutral medium (pH = 7) :
`MnO_(4)^(-)+2H_(2)O+3e rarr MnO_(2)("brown precipitate") + 4OH^(-)`
Reduction in alkaline medium `(pH gt 7)` :
`MnO_(4)^(-)e rarr MnO_(4)^(2-)` (green)