The half life of a freshly prepared radioactive sample is 2h. If the sample emits radiation of intensity, which is 16 times the permissible safe level, then the minimum time taken after which it would be possible to work safely with source is:

Answer

8

Explanation

Here, `T=2h, t=?`
To work safely with the sample, its activity must be reduced to `1/16`.
form `N/(N_(0))=(1/2)^(n)=1/16=(1/2)^(4)`
`:. n=4`
`t=nT=2xx4=8h`