Which of the following increases the motion of atoms and molecules?

• A. Decreasing the temperature
• B. Placing the substance in a vacuum
• C. Increasing the temperature
• D. Adding a catalyst

Answer: (C)

Verified step by step guidance

1. Understand that the motion of atoms and molecules is directly related to their kinetic energy, which depends on temperature.
2. Recall that increasing temperature increases the average kinetic energy of particles, causing them to move faster.
3. Recognize that decreasing temperature reduces kinetic energy, thus decreasing motion.
4. Note that placing a substance in a vacuum does not inherently increase particle motion; it mainly affects pressure and volume conditions.
5. Understand that adding a catalyst speeds up a chemical reaction by lowering activation energy but does not increase the motion of atoms or molecules themselves.