(a) ΔG° = -2.303 RT logK If K > 1, ΔG° will be less than zero because products formed are more than that of reactants, i.e., process is spontaneous in forward direction.
(b) It is because heat energy is required to overcome activation energy.
(c) ΔG = ΔH - TΔS, At low temperatures ΔH > TΔS whereas at high temperature TΔS >ΔH
∴ ΔG decreases, i.e., becomes negative.