Question

The half-life period of a radioactive element is $40$ days. If $32\, g$ of this element is stored for $160$ days, calculate the weight of the element that would remain in gram.

Answer 1

Amount remaining after $n$ half lives is

$N=\frac{N_{0}}{2^{n}}\left(N_{0}=\right.$ initial amount $)$

$=\frac{32}{(2)^{4}}=2 \,g$

$\left[n=\right.$ number of half lives $\left.=\frac{160}{40}=4\right]$