PbO₂  $$ \to $$ PbO; $$\Delta $$G₂₉₈ < 0
SnO₂ $$ \to $$ SnO;  $$\Delta $$G₂₉₈ > 0

Most probable oxidation state of Pb and Sn will be

Enthalpy of CH₄ + $${1 \over 2}$$ O₂ $$ \to $$ CH₃OH is negative. If enthalpy of combustion of CH₄ and CH₃OH are x and y respectively. Then which relation is correct?

The entropy change in the fusion of one mole of a solid melting at 27^oC (latent heat of fusion is 2930 J mol^–1) is :

2Zn + O₂ $$ \to $$ 2ZnO;  $$\Delta $$G^o = $$-$$ 616 J
2Zn + S₂ $$ \to $$ 2ZnS;  $$\Delta $$G^o = $$-$$ 293 J
S₂ + 2O₂ $$ \to $$ 2SO₂;   $$\Delta $$G^o = $$-$$408 J
$$\Delta $$G^o for the following reaction
2ZnS + 3O₂ $$ \to $$  2ZnO + 2SO₂ is