consider the cooling curve above. the substance is changing state from a gas to a liquid to a solid. as the temperature changes we also know that
a) there is a decrease in molecular attraction and kinetic energy.
b) there is a decrease in kinetic energy and the molecules get closer together.
c) kinetic energy increases while potential energy decreases during the phase changes.
d) although the molecules get closer together, there is no real change in the energy of the molecules.