(a) Account for the following:
(i) Manganese shows maximum number of oxidation states in 3d series?
(ii) `E^@` value for `Mn^(3+)| Mn^(2+)` couple is much more positive than that of `Cr^(3+)| Cr^(2+)` .
(iii) `Ti^(4+)` is colourless whereas `V^(4+)` is coloured in an aqueous solution.
(b) Write the chemical equations for the preparation of `KMnO_4` from `MnO_2`. Why does purple colour of acidified permanganate solution decolourise when it oxidise `Fe^(2+)` to `Fe^(3+)` .