The average size of the molecules decreased. The average size of the molecules increased. The average kinetic energy of the molecules decreased. The average kinetic energy of the molecules increased.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which statement best describes the molecules in a sample of water that was heated from a liquid to a gas?
Possibilities:
- The average size of the molecules decreased.
- The average size of the molecules increased.
- The average kinetic energy of the molecules decreased.
- The average kinetic energy of the molecules increased.

The average kinetic energy of the molecules increased.