Give reason:
(i) Transition metals show variable oxidation states.
(ii) Actinoids show wide range of oxidation states.

Explanation

(i) Transition elements have their valence electrons in `(n-1)` d and ns orbitals. Since there is very little difference in the energies of these orbitals, both energy levels can be used for bond formation and thus, give variable oxidation states.
(ii) The energy gap between 5f, 6d and 7s subshells is very small and hence all the electrons present in these subshells can participate in bonding. Thus, Actinoids show wide range of oxidation states.