In group IV, the stability of the plus 2 oxidation state relative to the plus 4 state
- A. decreases down the group
- B. is the same throughout
- C. is zero for all members
- D. increases down the group, so lead two compounds are more stable than lead four
Explanation
This is the inert pair effect: the two s electrons of the outer shell become progressively harder to involve in bonding as the group is descended, so tin favours plus 4 while lead favours plus 2. It follows that lead four compounds such as PbO2 are strong oxidising agents, readily reverting to lead two. The same effect appears in groups III and V.