Which process is defined as the removal of heat from an object by the vaporization of liquid?

• A. Evaporation
• B. Conduction
• C. Radiation
• D. Convection

Answer: (A)

Cooling happens when liquid at a surface absorbs heat until some molecules escape as vapor. Those escaping molecules take away energy, the latent heat of vaporization, from the object, so its temperature falls. This can occur even below the liquid’s boiling point, which is why evaporative cooling works in sweating and many cooling processes. Other modes of heat transfer—conduction through contact, convection with moving fluid, and radiation from a distance—transfer energy without a phase change. Because the scenario specifies heat removal by vaporizing the liquid, evaporation best describes the process.