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An endothermic process is not spontaneous at the freezing point of water but turns spontaneous at the boiling point of water. Which statement about its thermodynamic quantities is correct?

1. Both ΔH and ΔS are positive.
2. Both ΔH and ΔS are negative.
3. ΔH is positive and ΔS is negative.
4. ΔH is negative and ΔS is positive.

Correct answer: Both ΔH and ΔS are positive.

Solution

In an endothermic process, heat is absorbed, which means ΔH is positive. Additionally, for the process to become spontaneous at higher temperatures, the entropy change ΔS must also be positive, indicating an increase in disorder.

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