Explain why does colour of `KMnO_(4)` disappear when oxalic acids is added to its solution in acidic medium.

Explanation

This is a redox reaction in which `MnO_(4)^(-)` ions ( pink colour) are reduced to `Mn^(2+)` ions (colourless). At the same time oxalate ion in the acidic medium are oxidised to `CO_(2)`.
`5C_(2)O_(4)^(2-)(aq)+ underset("(Colour)")(2MnO_(4)^(-)(aq))+16H^(+)(aq) to underset("(Colourless)")(2Mn^(2+)(aq))+8H_(2)O(aq)+10CO_(2)(g)`