Which of the following would decrease the rate of a chemical reaction?

• A. Increasing the surface area of a solid reactant
• B. Adding a catalyst
• C. Increasing the concentration of reactants
• D. Lowering the temperature

Answer: (D)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on factors such as temperature, concentration, surface area, and catalysts.
2. Recall that increasing the surface area of a solid reactant generally increases the reaction rate because more particles are exposed to react.
3. Know that adding a catalyst lowers the activation energy, which increases the reaction rate without being consumed.
4. Recognize that increasing the concentration of reactants increases the frequency of collisions, thus increasing the reaction rate.
5. Identify that lowering the temperature decreases the kinetic energy of particles, reducing the frequency and energy of collisions, which decreases the reaction rate.