Which process involves particles gaining energy to transition from a liquid to a gas?

The process in which particles gain energy to transition from a liquid to a gas is boiling. During boiling, the particles in the liquid absorb enough heat energy that they overcome the intermolecular forces holding them together, allowing them to break free and enter the gas phase. This occurs at a specific temperature called the boiling point. Essentially, boiling involves the transformation of a liquid into a vapor, where the liquid particles spread out and move freely as gas particles.

In contrast, freezing is the process of a liquid losing energy and transitioning into a solid. Condensation refers to the process where gas particles lose energy and transition back to the liquid state, while melting is the process of a solid gaining energy to become a liquid. Therefore, boiling is the correct choice as it directly describes the process of gaining energy to change from a liquid to a gas.