Concept:Collision theory states that reactant particles must collide with sufficient energy and proper orientation for a reaction to occur. Such successful collisions are called effective collisions.
Explanation:Not every collision leads to a reaction.
Ineffective collisions do not produce a chemical change.
So options A, B, and D are incorrect statements about collision theory.
Only effective collisions result in product formation.
The rate of reaction depends directly on the number of effective collisions per unit time.
Thus, the rate of reaction is proportional to the number of effective collisions.
More effective collisions lead to a faster reaction.
Answer:C. The rate of reaction is proportional to the number of effective collisions.