Step 1: Understanding Inert Pair Effect:
In Group 14 (C, Si, Ge, Sn, Pb), the stability of the +4 oxidation state decreases down the group, and the stability of the +2 oxidation state increases due to the inert pair effect.
- For Tin (Sn), +4 is more stable than +2. So, \( \text{Sn}^{2+} \) wants to become \( \text{Sn}^{4+} \) (oxidation). Hence, \( \text{Sn}^{2+} \) is a good reducing agent.
- For Lead (Pb), +2 is more stable than +4. So, \( \text{Pb}^{4+} \) wants to become \( \text{Pb}^{2+} \) (reduction). Hence, \( \text{Pb}^{4+} \) is a good oxidising agent.
Step 2: Analyzing Statement C:
Statement (C) says "Lead in +2 state acts as good reducing agent". This would imply \( \text{Pb}^{2+} \) oxidises to \( \text{Pb}^{4+} \). However, \( \text{Pb}^{2+} \) is the stable state. It does not want to lose electrons. Therefore, this statement is incorrect.
Step 3: Analyzing other statements:
(A) Correct. Carbon shows -4 in \( \text{CH}_4 \), etc.
(B) Correct. \( \text{Sn}^{2+} \) reduces to \( \text{Sn}^{4+} \).
(D) Correct. \( \text{Pb}^{4+} \) oxidizes to \( \text{Pb}^{2+} \).