Why does an evaporating liquid cool down according to the Kinetic Molecular Theory? Heat is required to evaporate a liquid. Heat must be dissipated to break the liquid bonds. ) Heat is lost through elastic collisions. The highest velocity molecules are lost.

ccording to the Kinetic Molecular Theory, an evaporating liquid cools down because the highest velocity molecules are lost. When a liquid evaporates, the molecules with the highest kinetic energy (or speed) escape from the surface of the liquid into the gas phase. This leaves behind molecules with lower average kinetic energy, resulting in a decrease in the temperature of the remaining liquid. Therefore, the correct explanation is that "The highest velocity molecules are lost."