Approximately how many half-life periods must elapse if the activity of a radioactive isotope sample is to be reduced to 0.004 of the original value?

Question

Quizplus · Accepted Answer

The activity of a radioactive isotope sample reduces by a factor of two in each half-life period. Therefore, to reduce the activity to 0.004 of the original value, we need to divide the original activity by 2 six times:

1/2^6 = 1/64 ≈ 0.016

So, approximately 6 half-life periods must elapse for the activity of the sample to be reduced to 0.004 of the original value. Therefore, the correct answer is choice C.

Approximately How Many Half-Life Periods Must Elapse If the Activity