Correct Answer - C
Addition of a few crystals of `MnSO_(4)` greatly accelerates the reduction by oxalic acid of purple `KMnO_(4)` to nearly colourless manganese (II). When no manganese (II) ion is added, the reaction initially proceeds slowly, but the rate gradually increases because the product manganese (II) autocatalyses the reaction.
`5H_(2)C_(2)O_(4)+2KMnO_(4)+3H_(2)SO_(4)to2MnSO_(4)+K_(2)SO_(4)+10CO_(2)+8H_(2)O`
