How many atoms of zinc-69 remain after a sample of 500,000 zinc-69 atoms decays for a period of 165 minutes? The half-life time for zinc-69 is 55 minutes.

Question

Quizplus · Accepted Answer

The half-life of zinc-69 is 55 minutes. After 165 minutes, which is 3 half-lives (165/55 = 3), the number of atoms remaining is (1/2)^3 of the original amount. Therefore, 500,000 * (1/2)^3 = 62,500 atoms remain.

How Many Atoms of Zinc-69 Remain After a Sample of 500,000