Answer the following questions about the concept of half-life and periodic removal of nuclei from a radioactive sample.
(i) State the meaning of the term "half-life" of a radioactive isotope.
(ii) Give a reasoned explanation of why removing a fixed fraction of the undecayed nuclei at regular intervals does not change the numerical value of the isotope’s half-life.
(iii) Consider a sample from which exactly one-third of the undecayed nuclei is taken away at the end of each half-life. Explain qualitatively, without performing detailed calculations, whether the amount of undecayed nuclei present after three half-lives will be greater than, equal to, or less than that in an undisturbed sample, and justify your answer.