Answer:
One-eighth of an original radioactive sample will remain at the end of THREE half-lives
Explanation:
As we know that half life is defined as the time after which a radioactive nuclei will remain half in the number as we compare it with the initial amount present in the sample.
So here let say initially sample contains N number of radioactive atoms
so after one half life we will have "N/2" present in that sample
after 2nd half life the number of nuclei again becomes half of the remaining
\(N_1 = \frac{N}{4}\)
now after 3rd half life we can say
\(N_2 = \frac{N}{8}\)
so here correct answer will be
One-eighth of an original radioactive sample will remain at the end of THREE half-lives
