Which term describes the transformation from liquid to gas?

• A. Evaporation
• B. Condensation
• C. Sublimation
• D. Freezing

Answer: (A)

The main idea here is vaporization, specifically evaporation. Evaporation is when a liquid turns into a gas as molecules at the surface gain enough energy to break free from intermolecular forces and escape into the air. It can happen at temperatures below the liquid’s boiling point, and it tends to be a surface phenomenon and relatively gradual. In contrast, boiling (another form of vaporization) occurs throughout the liquid at its boiling temperature. The other options describe different phase changes: condensation is gas turning into liquid, sublimation is solid turning into gas, and freezing is liquid turning into solid. In physiology, evaporation is also the key cooling mechanism in sweating, where energy is used to vaporize water from the skin, producing a cooling effect.