Which of the following leads to an increase in the rate of a chemical reaction?

• A. Adding an inert gas at constant volume
• B. Reducing the surface area of a solid reactant
• C. Decreasing the temperature
• D. Increasing the concentration of reactants

Answer: (D)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on factors that affect the frequency and energy of collisions between reactant molecules.
2. Recognize that adding an inert gas at constant volume does not change the concentration of reactants, so it generally does not affect the reaction rate.
3. Know that reducing the surface area of a solid reactant decreases the available area for collisions, thus decreasing the reaction rate.
4. Recall that decreasing the temperature lowers the kinetic energy of molecules, reducing the frequency and energy of collisions, which slows down the reaction rate.
5. Identify that increasing the concentration of reactants increases the number of molecules per unit volume, leading to more frequent collisions and therefore an increased reaction rate.