Which of the following actions would most likely cause an increase in the energy of water molecules in liquid water?

• A. Heating the water
• B. Allowing the water to evaporate at room temperature
• C. Adding salt to the water
• D. Placing the water in a freezer

Answer: (A)

Verified step by step guidance

1. Understand that the energy of water molecules in liquid water is related to their kinetic energy, which increases with temperature.
2. Recognize that heating the water directly adds thermal energy, increasing the kinetic energy of the water molecules and thus their overall energy.
3. Consider that allowing water to evaporate at room temperature removes higher-energy molecules from the liquid, which actually decreases the average energy of the remaining liquid water molecules.
4. Note that adding salt to water affects the solution's properties but does not directly increase the kinetic energy of the water molecules; it may even lower the vapor pressure and freezing point.
5. Placing water in a freezer lowers the temperature, reducing the kinetic energy and energy of the water molecules.