ΔH is negative and ΔS is positive
ΔH is positive and ΔS is negative
both ΔH and ΔS are positive
both ΔH and ΔS
A spontaneous reaction is impossible if ΔH is positive and ΔS is negative as it will lead to a positive value of ΔG. For a reaction to be non-spontaneous, ΔG should be positive. Note: When ΔH is positive and ΔS is negative, ΔG = ΔH - TΔS; ΔG = positive - T × negative; ΔG = positive + positive; ΔG = positive