`75%` of a first-order reaction was completed in `32` minutes, when was `50%` of the reaction completed ?

Options

A. 16 min
B. 24 min
C. 8 min
D. 4 min

Answer

A

Explanation

`k=(2.303)/(t)log.((a)/(a-x))`
`k=(2.303)/(32)log.((100)/(100-75))` … (i)
`k=(2.303)/(t)log.((100)/(100-50))` ….(ii)
From the two equation (i) and (ii), t=16 minutes .