How is the variability in oxidation states of transition metals different from that of the non transition metals?
Illustrate with examples.

Explanation

It is due to the incomplete filling of d-orbitals in such a way that their oxidation states differ from each other by unity, e.g., `Fe^(2+)` and `Fe^(3+),Cu^(o+)` and `Cu^(2+)` etc.
In case of non-transition elements, the oxidation states differ by units of two e.g., `Pb^(2+)` and `Pb^(4+)`,`Sn^(2+)` and `Sn^(4+)` etc. Moreover, in transition elements, the higher oxidation states are more stable for heavier elements, in a group. For example, in group 6, `Mo^(6+)` and `W^(6+)` are more stable than `Cr^(6+)`. In p-block elements, the lower oxidation states are more stable for heavier members due to inert pair effect, e.g., in group `16,Pb^(2+)` (3 is more stable tan `Pb^(4+)`).