What process occurs when a liquid transforms into a solid?

The process in which a liquid transforms into a solid is known as freezing. During freezing, the temperature of the liquid decreases to a point where the molecules lose sufficient kinetic energy to form stable bonds with each other, resulting in the formation of a solid structure. This transformation is typically associated with water becoming ice as it cools.

In contrast, the other processes mentioned have different definitions. Evaporation refers to the transition of a liquid into a gas when molecules at the surface of the liquid gain enough energy to break free. Condensation is the process where a gas turns back into a liquid, often when temperature drops or pressure increases. Fission, usually associated with nuclear reactions, involves the splitting of atomic nuclei and has no relation to state changes between liquid and solid. Thus, freezing is the correct term for the conversion of a liquid into a solid.