1. Transition metals can act as catalysts because these can change their oxidation state. How does Fe (III) catalyse the reaction between iodide and persulphate ions?

2.  Mention any three processes where transition metals act as catalysts.

NEETprep Answer: (a) Reaction between iodide and persulphate ions is 
              2I- + S2O82    Fe(lll) l2 + 2SO42-

Role of Fe(lll) ions        2Fe3+ + 2l-  2Fe2+ + l2
                                      2Fe2+ + S2O82-  2Fe3+ + 2SO42-
(b) (i) Vanadium (V) oxide used in contact process for oxidation of SO2 to SO3
(ii) Finely divide iron in Haber's process in conversion of N2 and H2 to NH3.
(iii) MnO2  in preparation of oxygen from KCIO3.