What happens to gas molecules when heated in a confined space?

When gas molecules are heated in a confined space, they gain energy, which causes them to move faster. This increase in molecular speed leads to more frequent and forceful collisions with the walls of the container, resulting in an increase in pressure if the volume is held constant. This behavior is explained by the kinetic molecular theory, which states that the temperature of a gas is directly related to the average kinetic energy of its molecules. As the temperature rises, the increased energy translates into greater movement, confirming that the correct response is that the gas molecules move faster when heated.