What happens to water in liquid state at reduced pressure?

When water is at a reduced pressure, it experiences a decrease in the boiling point. This phenomenon occurs because the pressure above the liquid state influences the energy necessary for molecules to escape into the vapor phase. As the pressure drops, the energy required for molecules to overcome intermolecular forces is reduced, allowing more molecules to transition from the liquid state to the vapor state even at lower temperatures.

This principle is particularly relevant in applications like vacuum distillation, where liquids can boil and vaporize at much lower temperatures than under atmospheric pressure. Therefore, water will convert to vapor when subjected to reduced pressure, making it the correct response to the question.

In contrast, freezing or remaining unchanged would not accurately describe the behavior of water in this scenario under reduced pressure. Evaporation at a higher temperature also does not apply, as reducing pressure generally lowers the temperature at which evaporation occurs. Thus, the transformation from liquid to vapor due to reduced pressure highlights the relationship between pressure and phase changes in substances like water.