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 decay of a radioactive substance follows an exponential decay model, where the amount of substance remaining after time t is given by:
N(t) = N0 (1/2)^(t/T1/2)

where N0 is the initial amount of substance and T1/2 is the half-life of the substance.

Substituting the given values, we get:

N(t) = 500,000 (1/2)^(165/55) = 62,500

Therefore, the number of atoms of zinc-69 remaining after 165 minutes is 62,500. The best choice is B.

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