How is `KMnO_(4)` [Potassium permanganate] is prepared from `MnO_(2)`? Write equations.

Explanation

`KMnO_(4)` is prepared by fusion of `MnO_(2)` with alkalimetal hydroxide and an oxidizing agent like `KNO_(3)`. The produces the dark green `k_(2)MnO_(4)` which on acidification gives permangante.
`2MnO_(2)+4kOH+O_(2)rarr 2k_(2)MnO_(4)+2H_(2)O`
`3MnO_(2)^(2-)+4H^(+)rarr 2MnO_(4)^(-)+MnO_(2)+2H_(2)O`