Question

When $KMn{O}_4$ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because:

• A. $C{O}_2$ is formed as the product
• B. reaction is exothermic
• C. $Mn{O}_4^{-}$ catalyses the reaction
• D. $M{n}^{2+}$ acts as autocatalyst

Answer 1

The correct option is D $M{n}^{2+}$ acts as autocatalyst

Here, KMnO4 is a reactant in the reaction which forms $M{n}^{2+}$ which acts as an auto-catalyst. The reaction is slow initially because ${Mn{O}_4}^{-}$ is getting converted to $M{n}^{2+}$ but once $M{n}^{2+}$ forms, the reaction becomes faster due to the catalytic action.

Hence, option D is correct.