In a first order reaction , the concentration of the reactant is reduced to 12.5% in one hour when was is reduced to 12.5 % in one hour . When was it half completed ?

Options

A. `30` min
B. 3 hr
C. 15 min
D. 20 min

Answer

D

Explanation

`12.5%` reduced in one hour (60 min) = `((1)/(2))^(3)=(1)/(8)`
3 Half life = 60 min
Half life = 20 min