Statement I: Spraying of water causes cooling.
Statement II: For an isolated system, surface energy increase on the expense of internal energy.

In ......... process , work is done at the expense of internal energy .

When is the heat supplied to a system equal to the increase in its internal energy?

Statement- 1 : On sudden expansion a gas cools. Statement - 2 : On sudden expansion , no heat is supplied to system and hence gas does work at the expense of its internal energy.