Q.
The reaction in which standard reaction entropy change ((ΔS)o) is positive and standard Gibb's energy change ((ΔG)o) decreases sharply with increasing temperature is:
Cgraphite+21(O2)(g)→COg Δng=1−21=21
As amount of gaseous substance is increasing in product, thus ΔS is positive for this reaction.
And we know that ΔG=ΔH−TΔS
As ΔS is positive, thus increase in temperature will make TΔS more negative and ΔG will decrease.