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A freshly prepared radioactive source of...

A freshly prepared radioactive source of half-life 2 h emits radiation of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is

A

128 h

B

24 h

C

6h

D

12h

Text Solution

Verified by Experts

The correct Answer is:
D
After n number of half-life, `N=N_(0)((1)/(2))^(n)`
`1=64((1)/(2))^(n)implies((1)/(2))^(6)=((1)/(2))^(n)`
n = 6 i.e., half-lives
`therefore"Minimum time,"t=6xx2=12h`
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