As the temperature of a chemical reaction in the gas phase is increased, the rate of the reaction increases because

(1) fewer particle collisions occur

(2) more effective particle collisions occur

(3) the required activation energy increases

(4) the concentration of the reactants increases

Answer: option (2) more effective particle collisions occur.

Justification:

Always keep in mind that the temperature is a measure of the average kinetic energy of the particles.

The higher the temperarute the hiigher the kinetic energy.

Also, remeber that the kinetic energy is the energy of motion: the higher the kinetic energy the hgher the speed of the particles and the more energetic the collisions.

Therefore, those more energetic collisions will increase the number of collisions that overcome the activiation energy leading to higher rate of conversion (reaction), whic is what a more effective particle collisions occur mean.