Final answer:
The volume of a substance increases the most during vaporization.
Step-by-step explanation:
The change of state during which the volume of a substance increases the most is vaporization. Vaporization is the process in which a substance changes from a liquid to a gas. When a substance vaporizes, the particles gain enough energy to break free from the attractive forces in the liquid phase and move more freely in the gaseous phase. This increased movement and separation leads to an expansion of volume.
Learn more about change of state