Question 346: Atoms & Nuclei

Question

A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _________ hours.

Accepted Answer

$${T_{1/2}} = 150$$ minutes
$${A_0} = 64x$$, where x is safe limit
$$x = 64x 	imes {2^{ - {n \over {{T_{1/2}}}}}}$$
$$ \Rightarrow {1 \over {64}} = {2^{ - {n \over {{T_{1/2}}}}}}$$
or $${n \over {{T_{1/2}}}} = 6$$
$$ \Rightarrow n = 6 	imes 150$$ minutes
= 15 hours

Atoms & Nuclei

A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _________ hours.

Integer / Numeric Answer Type