The reactin `2X to B` is a zeroth order reaction. If the initial concentration of X is 0.2 M, the half-life is 3h. When the initial concentration of X is 0.5 M, the time required to reach its final concentration of 0.2 M will be:

Options

A. 18.0 h
B. 12.0 h
C. 7.2 h
D. 9.0h

Answer

A

Explanation

`t_((1)/(2))=(C_(o))/(2k) rArr 6=(0.2)/(2k) rArr k=(1)/(60)`
`k=(C_(o)-C_(t))/(t) rArr (1)/(60) =(0.5-0.2)/(t)" "therefore" t=18 h"`