Question

$\text{16} \, \text{g}$ of a radio active substance is reduced to $\text{0} \text{.5} \, \text{g}$ after $\text{1}$ hour. The half life of the radioactive substance in minutes is:

Answer 1

Radioactive disintegration is following first order kinetic reaction. The probability per unit time that a nucleus will decay is a constant, independent of time”. It is represented by λ (lambda) and is called decay constant.
Integrated rate equation:
$\lambda =\frac{1}{t}ln\frac{16}{0.5}$
$\lambda =5\times ln2$
Half life period:
$t_{\frac{1}{2}}=\frac{l n 2}{\lambda }=\frac{1}{5} \, hr=12 \, min$