How would you account for the following ?
(i) With the same d-orbital configuration `(d^(4)) Cr^(2+)` is reducing agent while `Mn^(3+)` is an oxidizing agent.
(ii) The actinoids exhibits a larger number of oxidation states than the corresponding members in the lanthanoid series.
(iii) Most of the transition metal ions exhibit characteristic in colours in aqueous solutions.