Define the following terms :
(i) Half- life of a reaction `(t_(1//2))`
(ii) Rate constant `(k)`.

Explanation

(i) Rate Constant : Rate constant is defined as the rate of a reaction when concentration of
the reactionts is unity . It is defined by k.
Unit of k is `mol^(1-n) L^(n-1)S^(-1),` where n is the order of the reaction.
(ii) Half life period of a reaction`(t1//2)` : The half life of a reaction is the time period in which
the concentration of a reactant is reduced to one half of its initial concentration.