Question

What action will slow down the rate of a reaction?

a. Raising the temperature of the reactants
b. Decreasing surface area of a solid reactant
c. Increasing the concentration of the reactants
d. Adding a catalyst to the reaction

Answer 1

B. Decreasing the surface area of solid reactant;
Why? Collision theory suggests that the more opportunities for reactants to come into contact or "collide" with other reactants, the faster the reaction will take place. Hence, decreasing the surface area will decrease the probability of collisions between reactants thereby decreasing reaction rate.