Question

Mean life of a radioactive sample is $100$ $s$. Find its half life in minutes

• A. $0.693$
• B. $1$
• C. ${10}^{-4}$
• D. $1.155$

Answer 1

The correct option is D $1.155$

$t_{av}$ = $\frac{1}{\lambda }$ $100$ $s$
$t_{1/2}$ = $\frac{.693}{\lambda }$ = $69.3$ $s$

Half life in minutes $=\frac{69.3}{60}=1.155$min