Courses
Courses for Kids
Free study material
Offline Centres
More
Store

# The half-life of $131I$ is 8 days. Given a sample of $131I$ 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 $t=0$

Last updated date: 16th Sep 2024
Total views: 80.4k
Views today: 0.80k
Verified
80.4k+ views
Hint: We can say that in general, there is an inverse relation between the half-life and the intensity of radioactivity of an isotope. Isotopes with a long half-life decay very slowly, and so produce fewer radioactive decays per second; their intensity is less. Isotopes with shorter half-lives are more intense. The last element in the periodic table that has a stable isotope is lead (Z = 82), with stability (i.e. half-lives of the longest-lived isotopes) generally decreasing in heavier elements.

At time $\mathrm{t}=0$, the nuclei start to decay and at any time after that some of the nuclei may have decayed. Up to time $\mathrm{t}=8$ days, about half the initial number of the nucleus have decayed and up to 16 days, only one-fourth of the initial number of the nucleus are left undecayed.