Which of the following statements is true?

a) entropy is not a state function.

b) endothermic processes decrease the entropy of the surroundings, at constant t and p.

c) endothermic processes are never spontaneous.

d) exothermic processes are always spontaneous.

e) none of the above are true.

E) None of the above are true.

Explanation:

The spontaneity of a reaction depends on the Gibbs free energy (ΔG).

ΔG depends on the enthalpy (ΔH) and on the entropy (ΔS), according to the following expression.

ΔG = ΔH - T.ΔS

where,

T is the absolute temperature.

Which of the following statements is true?

A) Entropy is not a state function. FALSE. Entropy is a state function, which means that it only depends on the initial and final state of a process.

B) Endothermic processes decrease the entropy of the surroundings, at constant T and P. FALSE. Whether a reaction is endothermic or exothermic depends on the enthalpy and it is not related to the entropy. In endothermic processes, ΔH > 0 and in exothermic ones ΔH < 0.

C) Endothermic processes are never spontaneous. FALSE. If ΔS > 0 and |T.ΔS| > |ΔH|, the reaction is spontaneous even if ΔH > 0 because ΔG < 0.

D) Exothermic processes are always spontaneous. FALSE. If ΔS < 0 and |T.ΔS| > |ΔH|, the reaction is nonspontaneous even if ΔH < 0 because ΔG > 0.

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