Question

the half life period of a first order rxn. is 60 minutes.what percentage will be left after 240 mnts????????????pls solve this

Answer 1

Half life is 60 minutes

The given time is 240 minutes, so it is abut four half lives.

$\frac{1}{2} ^{n}$= Fraction of the substance remaining

where n is number of half lives.

$\frac{1}{2}^{4}$ = 0.0625

The percentage of substance remaining after 240 min = 0.0625 * 100 = 6.25%