Collision Theory of Chemical Reactions

Barriers for a chemical reaction occurring based on collision theory are,
1. Reactant molecules should have enough kinetic energy to overcome the threshold energy barrier.
2. Reactant molecules that collide, should have proper _____ based on three-dimensional space. 

Collision theory is applicable to 

The minimum energy that all colliding molecules must possess in order to make the collisions effective is called _____ energy.(threshold/activation)

Collision theory is satisfactory for:-

Explain briefly the collision theory of bimolecular reactions.