Question

During the nuclear explosion, one of the products is ${}^{90}Sr$ with half life of 6.93 years. If 1 $\mu$g of ${}^{90}Sr$ was absorbed in the bones of a newly born baby in place of Ca, how much time, in years, is required to reduce it by 90% if it is not lost metabolically __________.
Given 9.9

Answer 1

Answer: 23.00

$k=\frac{0.693}{t_{1/2}}$
$=\frac{0.693}{6.93}=0.1yea{r}^{-1}$
$t=\frac{2.303}{k}\log \left(\frac{R_0}{R_t}\right)$
$R_0=1\mu g$
$R_t=1-1\times \frac{90}{100}$
$=0.1\mu g$
$=\frac{2.303}{0.1}\log \left(\frac{1}{0.1}\right)$
$=23.03years$