What are two main points of collision theory?

Explanation

(1) For reaction to occurs, there must be collisions between the reacting species.
(2) Only a certain fraction of total number of collisions are effective in forming products.
(3) For effective collision, the molecule under ordinary condition may vary from nearly zero to about one for ordinary reaction.
(a) Number of collisions per unit volume per sound collision (frequency) between reacting species.
(b) Fraction of effective collision properly and possessing sufficient energy:
i.e. Rate `= (-dx)/(dt) = fxz`