What occurs to gas molecules when they are heated and expand?

When gas molecules are heated, they absorb energy, which increases their kinetic energy. This increase in kinetic energy causes the molecules to move faster and collide with each other more frequently and forcefully. As a result, the molecules spread further apart, leading to an overall increase in volume if the gas is allowed to expand. This behavior aligns with the principles outlined in the kinetic molecular theory, which explains how temperature affects the motion of particles in a gas.

Under this theory, as temperature rises, the energy of the gas molecules increases, causing them to overcome intermolecular forces and move apart more significantly. Thus, when gas molecules are heated, they not only move faster but also create an increase in the distance between them, which explains why the correct answer addresses both the increased speed and the greater separation of the molecules.