Which statement best describes how temperature affects collision theory?

• A. Temperature has no effect on collision frequency.
• B. Temperature alone affects reaction orientation.
• C. Rate depends only on concentration, not temperature.
• D. Increasing temperature increases the average speed of the reactants, which increases the frequency of the collisions.

Answer: (D)

Temperature affects collision theory by changing how fast molecules move and how often they meet. When temperature increases, molecules gain kinetic energy and move faster, which raises the collision frequency—more collisions per unit time. This faster motion also shifts the energy distribution so a larger fraction of collisions have enough energy to overcome the activation barrier, making more collisions successful. The statement is the best because it directly ties higher temperature to faster motion and more collisions, which boosts the reaction rate. Other choices misstate the effect, such as claiming temperature has no impact on collision frequency, that it only changes orientation, or that the rate depends only on concentration.