Question

Starting with $1.0g$ of a radioactive sample, $0.25g$ of it is left after $5$ days. Calculate the amount which was left after one day.

Answer 1

$t=\frac{2.303}{K}log\left(\frac{1}{0.25}\right)$

$5=\frac{2.303}{K}log\left(\frac{1}{0.25}\right)$

$K=\frac{2.303}{5}log\left(\frac{1}{0.25}\right)$

$K=0.27{day}^{-1}$

$t=\frac{2.303}{0.27}log\left(\frac{1}{A}\right)$

$1=\frac{2.303}{0.27}log\left(\frac{1}{A}\right)$

$A=0.76g$