When water is heated, which of the following occurs?

• A. The water molecules lose energy and the temperature decreases.
• B. The kinetic energy of water molecules increases, leading to a rise in temperature.
• C. Water immediately freezes due to increased molecular motion.
• D. The density of water increases as it is heated.

Answer: (B)

Verified step by step guidance

1. Understand that heating water means adding energy to the system, specifically thermal energy.
2. Recall that temperature is a measure of the average kinetic energy of molecules in a substance.
3. When water is heated, the kinetic energy of the water molecules increases, causing them to move faster.
4. Faster molecular motion corresponds to an increase in temperature, not a decrease.
5. Note that increased temperature usually causes water to expand slightly, so its density decreases rather than increases.