Which of the following best describes the effect of adding thermal energy to a substance?

• A. Particle motion increases, temperature decreases, and the substance may change state.
• B. Particle motion remains unchanged, temperature increases, but the state cannot change.
• C. Particle motion increases, temperature rises, and the substance may change state (e.g., from solid to liquid).
• D. Particle motion decreases, temperature falls, and the substance remains in the same state.

Answer: (C)

Verified step by step guidance

1. Understand that thermal energy is the total kinetic energy of particles in a substance, which affects particle motion and temperature.
2. Recognize that adding thermal energy generally increases the kinetic energy of particles, causing them to move faster.
3. Know that as particle motion increases, the temperature of the substance typically rises because temperature is a measure of average kinetic energy.
4. Be aware that with enough added thermal energy, the substance can undergo a phase change (e.g., solid to liquid) where energy goes into changing the state rather than increasing temperature.
5. Conclude that the best description is: particle motion increases, temperature rises, and the substance may change state.