Which factor would NOT increase the rate of a chemical reaction?

• A. Higher temperature
• B. Larger surface area
• C. Presence of a catalyst
• D. Mass loss from the system

Answer: (D)

Rate of a reaction increases when there are more or more energetic collisions between reactant particles. Higher temperature makes molecules move faster, boosting both how often and how energetically they collide. A larger surface area for solid reactants provides more contact points, so collisions happen more readily. A catalyst offers an alternative pathway with lower activation energy, meaning more collisions lead to a successful reaction at the same conditions. Mass loss from the system does not actively enhance reaction speed; removing material can change concentrations or pressure, which might slow the reaction or have little effect, but it isn’t a mechanism that increases the rate.