What happens to the temperature of the liquid in a cup of water as some of the water evaporates?

A the temperature increases because there are fewer molecules to share energy between

B the temperature decreases because new molecular bonds form

C the temperature decreases because the most energetic molecules escape

D the temperature increases because the vapor pressure increases

Answer: c: The temperature decreases because the most energetic molecules escape

Explanation:

Evaporation is surface phenomenon in which liquid molecules gain energy from surrounding molecules and thus these high energy molecules escape from the surface in the form of vapors thus leaving low energy molecules in the system. As the kinetic energy of the left molecules decreases, the temperature of the molecules decreases as kinetic energy is directly proportional to temperature. Thus low temperature results in cooling of the system.