Question

The decay constant of a radioactive substance is 0.693 per minute. What will be the half-life and mean life of it?

Answer 1

Decay constant $k=0.693$ per min=$0.693/60$ per second

Hence half life of the substance=$\tau =\frac{ln2}{k}$

$=\frac{ln2}{0.693/60}s=60s$

The mean life of substance=$\frac{1}{k}$

$=\frac{60}{0.693}s=86.58s$