Answer :

(i)Entropy of vapourisation – (b)is always positive

Explanation: When the liquid vaporizes, the degree of the disorder increases, therefore, entropy is always positive.

(ii) K for the spontaneous process- (d) the ideal gas

Explanation: K is equilibrium constant and is always positive.∆_{r}H^{-} is large and positive for strong endothermic reaction and the value of K is smaller than 1.

∆_{r}H^{-} is large and negative for exothermic reaction and the value of K is larger than 1. ∆_{r}G^{-} is also negative and large.

To get a large value of K we need a strongly exothermic reaction, hence we go for completion of the reaction.

∆_{r}G^{-} depend on ∆_{r}S^{-} and if entropy changes then the value of K also get affected, which depend on whether ∆_{r}S^{-} is positive or negative.

(iii) Crystalline solid-state : (c) lowest entropy

Explanation: Crystalline solid state is the most ordered form so it has the lowest entropy and gaseous state is disordered state so highest entropy.

(iv) ΔU in adiabatic expansion – (a) decreases

Explanation, as there is no exchange of heat between system and surrounding, internal energy will decrease after applying some amount of pressure.

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