Which of the following statements about vaporization is true?

The statement about vaporization that is true explains that it occurs when a liquid's surface molecules gain enough energy to transition into the gaseous state. This process can happen at any temperature, as long as the molecules at the surface of the liquid have enough energy to break free from the liquid's intermolecular forces. Vaporization is not limited to the boiling point; it can occur at lower temperatures as well, which is why evaporation happens even on days that are not boiling hot. This concept is fundamental in understanding how liquids can turn into gases under various conditions.

The other statements do not accurately represent the process of vaporization. For example, stating that it occurs only at boiling point is incorrect, as vaporization (specifically evaporation) can take place at any temperature. The idea that it is a cooling process reflects a result of the phenomenon; as molecules escape, the average kinetic energy of the remaining liquid decreases, leading to a cooling effect. However, this does not define vaporization itself. Lastly, vaporization does not require a vacuum to occur; it can happen in normal atmospheric conditions.