Which is the phase change in which a substance changes from a gas to liquid?

Condensation

Explanation:

The phase change in which a substance changes from a gas to liquid is Condensation.

There are 3 natural states of matter;

Solids, Liquids, and Gases.

Matter under certain conditions can change from one state to another. When Solids are heated they change into Liquids through the process of Heating. Upon cooling, the Liquids convert to Solid through freezing. When a Liquid such as water is heated, it converts into the Gaseous state through evaporation. Upon cooling, the Gas converts back into the Liquid state through Condensation.