As a substance changes from a liquid to a gas, the average distance between molecules ...

(1) decreases

(2) increases

(3) remains the same

Answer: increases

Explanation:

Matter exists in three different states, they are solids, liquids and gases. And each of them contains molecules with a certain amount of kinetic energy.

Hence, the addition of heat changes a substance from a liquid to a gas through a process called vaporization, whereby liquid molecules on changing to gases acquire a higher kinetic energy, and move more freely within the containing vessel.

Thus, the higher kinetic energy explains the increase in the average distance between molecules.