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

Answer: 12

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:
$t_{\frac{1}{2}}=\frac{ln2}{\lambda }=\frac{1}{5}hr=12min$