Question

Element which act as a strong oxidising agent in its +4 oxidation state is

• A. C
• B. Sn
• C. Pb
• D. Si

Answer 1

The correct option is C Pb

Pb shows mainly +2 oxidation state frequently as compared to +4 oxidation state. This is due to the inert pair effect. Inert pair effect may be defined as inertness of inner ns sub-shell towards chemical reaction. It is seen in group 3A and 4A group especially (5s and 6s electrons).
Carbon and silicon mostly show +4 oxidation state. Tin forms compounds in both oxidation states.
So as we move down the group, due to inert pair effect lower oxidation state become more stable.
Stability of +2 oxidation state,
$G{e}^{2+}<S{n}^{2+}<P{b}^{2+}$
Due to higher stability of $P{b}^{2+}$, $P{b}^{4+}$ will readily undergo reduction to form $P{b}^{2+}$. Thus, $P{b}^{4+}$ act as a strong oxidising agent.