Final answer:
The type of phase change that occurs going from B to A on the phase diagram is condensation.
Step-by-step explanation:
The type of phase change that occurs going from B to A on the phase diagram is condensation.
Condensation is the process by which a gas or vapor changes into a liquid. In this phase change, the substance loses energy and transitions from the gas phase to the liquid phase.
For example, when water vapor in the air comes into contact with a cold surface, it condenses into liquid water as tiny droplets, forming dew or fog.