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Which statement about a spontaneous process is correct?

1. A decrease in energy during a process is the sole condition for it to be spontaneous.
2. In an isolated system, a spontaneous process is accompanied by an increase in entropy.
3. Processes that absorb heat can never occur spontaneously.
4. Any process that releases heat must always be spontaneous.

Correct answer: In an isolated system, a spontaneous process is accompanied by an increase in entropy.

Solution

A spontaneous process in an isolated system tends to increase the overall disorder or entropy, reflecting the natural tendency of systems to evolve towards a state of higher entropy.

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