Question

an increase in temperature affects the reaction rate by
decreasing the velocities of particles that collide in the reaction.
increasing the number of molecules that have sufficient kinetic energy to react.
increasing the number of molecules that have sufficient potential energy to react.
decreasing the energy that particles need to overcome the energy activation barrier.

Explanation:

To solve this, we analyze each option based on chemical kinetics (part of Chemistry, a Natural Science subfield):

1. First option: Increasing temperature increases particle velocities (since kinetic energy \( KE = \frac{1}{2}mv^2 \) increases with \( T \)), so this is wrong.
2. Second option: Higher temperature means more molecules gain enough kinetic energy (from thermal energy) to exceed the activation energy, thus increasing the reaction rate. This matches the collision theory.
3. Third option: Reaction rate depends on kinetic (not potential) energy of colliding molecules, so this is incorrect.
4. Fourth option: Activation energy is a property of the reaction, not changed by temperature (catalysts lower activation energy, not temperature). So this is wrong.

Answer:

B. increasing the number of molecules that have sufficient kinetic energy to react.