Question

Collision theory is applicable to:
(A) Unimolecular reactions
(B) Bimolecular reactions
(C) Trimolecular reactions
(D) Tetramolecular reactions

Answer 1

Hint: As we know that the reaction takes place when two or more reactants are converted into products. The reaction totally depends upon the reactants. There are many types of reactions such as slow reactions, very fast reactions and moderate types of reactions. As the name indicated the collision theory explains the collision between the molecules which are changed into products.

Complete step by step answer:
As the name indicated the collision theory explains the collision between the molecules which are changed into products.
According to this theory, it is assumed that the reactant molecules are hard spheres and reaction between them occurs only when they collide with each other.
The number of collisions that takes place per second per unit volume of the reaction mixture is called collision frequency. And it is denoted as $$Z_{ab}$$.
For a collision to be effective, the colliding molecules must follow as-
(a) Energy factor-the colliding molecules must have energy greater than the threshold energy (the minimum energy for collision).
(b) orientation factor-the colliding molecules must have proper orientation at the time of collision.
If we see the above option
Option (A) is not the correct option because unimolecular reactions cannot collide.
Option (C) and Option (D) do not follow the orientation factor.

The collision theory is based on Arrhenius theory
According to Arrhenius theory:
“Rate constant of the reaction directly depends upon the temperature and inversely proportional to the activation energy.”

Therefore, the correct choice for this given question is B.

Note:
The collision theory although explains the results of the number of reactions but it has limitations that it does not take account of the structural aspects of the molecules.