Chemistry - Chemical Kinetics Question with Solution | TestHub

For a first order reaction, the half-life is given as $t_{1/2}=16$ minutes.

The time given is $t=32$ minutes.

The number of half-lives is $n=\frac{t}{t_{1/2}}=\frac{32}{16}=2$.

The fraction of the reactant remaining after $n$ half-lives is $\frac{1}{2^n}$.

Fraction remaining $=\frac{1}{2^2}=\frac{1}{4}$.

The fraction of the reactant that has reacted is $1-\frac{1}{4}=\frac{3}{4}$.

Answer: $3/4$