PbO2 ------- PbO dG(298k)
SnO2 ------- SnO dG(298k) 0
Most probable oxidation state of Pb and Sn will be
1- Pb4+ , Sn4+ 2- Pb4+,Sn2+
3- Pb2+, Sn2+ 4- Pb2+, Sn4+
The question is incorrect.
PbO2 → PbO ∆G(298k) <0
SnO2 → SnO ∆G(298k) > 0
The most probable oxidation state of Pb and Sn would be +2 and +4. The option 4 is correct.
In case of PbO2 , free energy change is -ve, that is it is favourable for forward reaction. The oxidation state of Pb in PbO is +2.
In case of SnO2, free energy change is +ve that is forward reaction is not favoured. The oxidation state of Sn in SnO2 is +4.