JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Topic Test - Nuclear Physics and Radioactivity

The half life of \[^{131}I\] is 8 days. Given a sample of \[^{131}I\] at time t = 0, we can assert that

A) No nucleus will decay before t = 4 days

B) No nucleus will decay before t = 8 days

C) All nuclei will decay before t = 16 days

D) A given nucleus may decay at any time after t = 0

Correct Answer: D

Solution :

[d] Number of nuclei decreases exponentially

\[N={{N}_{0}}{{e}^{-\lambda t}}\] and Rate of decay \[\left( -\frac{dN}{dt} \right)=\lambda N\]

Therefore, decay process losts up to t = ¥.

Therefore, a given nucleus may decay at any time after t = 0.