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

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13.Nuclei

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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$

(IIT-1998)

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 $t = \infty.$

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

Standard 12

Physics

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