The phase change that is an exothermic process is B. deposition. It is an exothermic process because it requires a release of heat to change from one phase to the other.
FURTHER EXPLANATION
Some changes in state are exothermic process while others are endothermic.
Exothermic Process
Exothermic processes release heat to the surroundings. The release of heat causes the particles of the substance to move slower and have less energy. Less energetic collisions of the particles results in the particles sticking to each other because there isn't sufficient energy to overcome the attractive forces acting on them.This results in the warming up of the surroundings which includes the container holding the substance.
Endothermic Process
Endothermic processes are processes that absorb heat from the surroundings. When particles absorb heat, they start to move faster and spread out.With the additional energy, the particles move faster and are able to overcome the attractive forces holding them together.This causes a cooling of the surrounding or the container.
A) Sublimation
Sublimation is phase change from solid to gas without passing through the liquid state. For the closely packed particles of the solid to spread out and change to its gaseous state, they must absorb heat. Therefore, this process is endothermic.
B) Deposition
This is the process of changing from gas to solid state without passing through the liquid state. For the particles of the gas to turn to solid, they must lose their energy so that when they collide with each other the attractive forces will hold them together forming the solid. This is an example of an exothermic process.
C. Vaporization
Particles of a vapor are farther away from each other than the particles of liquids. Liquids, therefore, need to be heated to turn them into gas or vapor. Since it requires absorption of heat, this is endothermic.
D. Melting
Solid particles are more closely packed than liquids. They are held by strong attractive forces that keep their movement limited to vibration in place. To change solids to liquids, their attractive forces must be overcome by heating. Absorption of heat makes the particles vibrate harder and overcome the attractive forces holding the solid together.
LEARN MOREEndothermic processes Enthalpy  Heat of Vaporization
Keywords: phase change, exothermic , endothermic
