When molecules are heated, which of the following best describes what happens to them?

• A. They stop vibrating and remain stationary.
• B. Their kinetic energy increases, causing them to move faster.
• C. They lose electrons and become ions.
• D. Their mass increases significantly.

Answer: (B)

Verified step by step guidance

1. Understand that heating molecules means adding thermal energy to the system.
2. Recall that temperature is a measure of the average kinetic energy of molecules in a substance.
3. When molecules are heated, their kinetic energy increases, which means they move faster and vibrate more vigorously.
4. Recognize that molecules do not stop vibrating or remain stationary when heated; instead, their motion intensifies.
5. Note that heating does not cause molecules to lose electrons or change their mass significantly; these are unrelated to the effect of temperature increase.