Question

The diagram shows the motion of a group of water molecules over a heat source.

How do the molecules at point A compare to the molecules at point B?

They are farther apart.
They have increased in size.
They have lost energy.
They are moving slower.

Answer 1

They are farther apart.

Near the heat source the molecules have gained kinetic energy, move faster, and spread out (lower density). They do not grow in size or lose energy, nor do they move slower.