The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half- lives have elapsed since the material was 100% parent atoms?

Question

Quizplus · Accepted Answer

The ratio of parent to daughter isotopes being 0.40 indicates that more than one half-life has passed but less than two, as one half-life would result in a 1:1 ratio (0.50), and two half-lives would result in a 1:3 ratio (0.25).

The Ratio of Parent to Daughter Isotopes in a Radioactive