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

• A. Increasing the concentration of reactants
• B. Increasing the surface area of a solid reactant
• C. Adding a catalyst
• 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 concentration, surface area, temperature, and catalysts.
2. Recall that increasing the concentration of reactants generally increases the reaction rate because more particles are available to collide.
3. Recognize that increasing the surface area of a solid reactant increases the reaction rate by exposing more particles to react.
4. Know that adding a catalyst speeds up the reaction by lowering the activation energy without being consumed.
5. Identify that lowering the temperature decreases the reaction rate because particles have less kinetic energy, leading to fewer effective collisions.