Final answer:
When water vapor becomes a liquid, it gives up heat energy.
Step-by-step explanation:
When water vapor becomes a liquid, it gives up heat energy.
Water has a high heat of vaporization, which means it requires a considerable amount of heat energy to change from a liquid to a gas. As liquid water heats up, the hydrogen bonding between water molecules makes it difficult for them to separate and enter the gaseous phase. However, once the heat energy is sufficient, the hydrogen bonds break and the water molecules escape from the liquid as water vapor.
Therefore, option a) Water vapor gives up heat energy, is the correct answer.