In view of the signs of `Delta_(r)G^(0)` for the following reactions
`PbO_(2)+Pbrarr2PbO,Delta_(r)G^(0)lt0`
`SnO_(2)+Snrarr2SnO,Delta_(r)G^(0)gt0`
Which oxidation state are more characteristic for lead and tin?

Options

A. For lead `+4` , for tin `+2`
B. For lead `+2` , for tin `+2`
C. For lead `+4` , for tin `+4`
D. For lead `+2` , for tin `+4`

Answer

A

Explanation

Oxidation state `underset(+4)pbO_(2)+underset(0)Pbrarrunderset(+2)2PbO`
Since `DeltaG^(@)lt0` , i.e., it is negative. Therefore, the reaction is spontaneous in the forward direction. This suggest `Pb^(2+)` is more stable than `Pb^(4+)` .
Oxidation state `underset(+4)SnO_(2)+underset(0)Snrarrunderset(+2)2SnO`
Since `DeltaG^(@)gt0` , i.e., it is positive, therefore, the reaction is non-spontaneous in the forward direction.But it will be spontaneous in the backward direction. This suggests that `Sn^(2+)` . These facts are also supported by the inert pair effect down the group.