When n small liquid drops, each having surface energy E, coalesce to form a single large drop, which of the following is/are correct?

Energy is released during the process
Energy is absorbed during the process
The magnitude of energy released or absorbed is E*(n - n^(2/3))
The magnitude of energy released or absorbed is n*E*(n^(2/3) - 1)

Correct answer: Energy is released during the process

Solution

When n drops merge into one, the total surface area decreases (since R = n^(1/3)*r), so surface energy decreases and the excess energy is released, usually as heat.

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