Which of the following catalysts and processes is incorrectly matched?

Which of the following reactions requires a catalyst?

In the reaction $KMnO_4 + H_2SO_4 + H_2C_2O_4$,the $Mn^{2+}$ ions act as:

According to the adsorption theory of catalysis,the rate of reaction increases because:

Platinised asbestos helps in the formation of $SO_3$ from $SO_2$ and $O_2$. But,if even a small amount of $As_2O_3$ is present,the platinised asbestos does not help in the formation of $SO_3$. $As_2O_3$ acts here as

Which of the following statements is wrong?