Chemistry - Complete P-block Question with Solution | TestHub

The Inert Pair Effect refers to the reluctance of the outermost $s$-electrons ($n{s}^2$) to participate in bonding in heavier elements, making lower oxidation states more stable.

(C) Pb²⁺ > Pb⁴⁺ is correct because, in Group 14, the +2 state becomes more stable than +4 as you move down to Lead.

(A) Hg > Hg²⁺ is correct because the $6s^2$ shell in Mercury is exceptionally stable due to relativistic effects (a form of the inert pair effect).

Bi³⁺ is more stable than Bi⁵⁺ (making B incorrect), and Fe is a transition metal where this effect does not apply.