Give reasons for the following:
(i) Transition metals exhibit a wide range of oxidation states.
(ii) Cobalt (II) is very stable in aqueous solutions but gets easily oxidised in the presence of strong ligands.
(iii) Actinoids exhibit a greater range of oxidation states than lanthanoids.

Explanation

(i) Due to in complete filling of d-orbitals.
(ii) because energy released in the formation of bond between `Co^(3+)` and ligand is more than the energy required for the conversion of `Co^(2+)` to `CO^(3+)`
(iii) N/A