50% completion of a first order reaction takes place in 16 minutes. Then fraction that would react in 32 minutes from the beginning

Amount of substance left after ‘n’ half lives$=\frac{{\mathrm{A}}_0}{2}$where

${\mathrm{A}}_0=$initial concentration of reactants ${\mathrm{t}}_{1/2}$=16 min

After 32 min that is 2 half lives amount of substance left $=\frac{{\mathrm{A}}_0}{2^2}=\frac{{\mathrm{A}}_0}{4}$

Fraction of reactants react = initial concentration -Amount of substance left 

$=\frac{{\mathrm{A}}_0-{\mathrm{A}}_0}{4}=\frac{3}{4}{\mathrm{A}}_0$Hence$\frac{3}{4}th$fraction of reactants reacted in 32 minutes