Identify the incorrect pair from the following:

Catalysts in the following reactions are:
$(I) CH_3COOCH_{3(l)} + H_2O_{(l)} \rightarrow CH_3COOH_{(aq)} + CH_3OH_{(l)}$
$(II) 2SO_{2(g)} + O_{2(g)} \rightarrow 2SO_{3(g)}$ (Contact Process)
$(III) 2SO_{2(g)} + O_{2(g)} \rightarrow 2SO_{3(g)}$ (Lead Chamber Process)
$(IV) N_{2(g)} + 3H_{2(g)} \rightarrow 2NH_{3(g)}$ (Haber Process)

What is a catalyst?

What role does adsorption play in heterogeneous catalysis?

$A$ catalyst is a substance which

When $KMnO_4$ solution is added to hot oxalic acid solution,the decolorization is slow in the beginning but becomes instantaneous after some time. This is because