Question

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.

Answer 1

I can confirm that the answer is B.

Answer 2

Answer: B)  there is a decrease in kinetic energy and the molecules get closer together.

Explanation: Kinetic energy is directly proportional to temperature, thus as temperature decreases, kinetic energy also decreases.

Gas is the state of matter in which particles are very loosely bound and hence can easily move past one another very easily and have highest kinetic energy.

Liquid is the state of matter in which particles are loosely bound and hence can move past one another easily and have high kinetic energy.

Solid is the state of matter in which particles are tightly bound and hence can not move easily and have low kinetic energy.

Thus on moving from gaseous to solid state, the kinetic energy decreases and the molecules get closer together.