Question

Compare non transition and transition elements on the basis of their --

stability of oxidation states

Answer 1

In tranistion metals the higher oxidation states are stable while in other non transition elements(specially in p-block elements) the lower oxidation states are mores stable.
Actually, in heavy transition metals, the d-orbital electrons and s-orbital electrons both are easily available for ionizations and so, they are quite stable in their higher oxidation states it is probably shown due to relatively small increase in successive ionisation energies which leads the element to show various oxidation states by separation of each electron.
But, in non transition elements the d-block is absent and also due to inert pair effect the lower oxidation states are stable down the group.
Actually, general electronic configuration of this group is ns²np³. They have 5 electrons in their valence shell. The inert pair effect is nothing but the extra stability concept in which the inner s-orbital electrons is reluctant towards bond formation and for which the oxidation states related to it is more stable. It gives increasing stability of oxidation states that are 2 less than the group valency when we travel down the group.