The dissociation of nitrogen pentaoxide is a first order reaction. In first `24 min`, `75%` of nitrogen pentaoxide is dissociated. What amount of nitrogen pentaoxide will be left behind after one hour of the start of reaction?

Options

A. Approximately `1%`
B. Approximately `2%`
C. Approximately `3%`
D. None

Answer

C

Explanation

`t_(75%) = 2t_(1//2)`
`:. t_(1//2) = (24 min)/(2) = 12 min`
`n =` Number of half in `1 hr (60 min) = (60)/(12) = 5`
Amount of substance left after `5` half lives
`= ((1)/(2))^(5) = (1)/(32)`
`:. %` of amount left `= (100)/(32) = 3.125% ~~ 3%`