Among the given reactions only in the case of C (graphite) +21O2( g)⟶CO(g) entropy increases because randomness (disorder) increases. Thus, standard entropy change (ΔS∘) is positive. Moreover, it is a combustion reaction and all the combustion reactions are generally exothermic, i.e., ΔH∘=− ve We know that ΔG∘=ΔH∘−TΔS∘ΔG∘=−vv−T(+ve) Thus, as the temperature increases, the value of ΔG∘ decreases.