Question

Suppose you have a 100 mg sample of Au-191, which has a half-life of 3.4 hours. How much will remain after 10.2 hours?

Answer 1

10.2 hours is equivalent to three half-lives, so after 10.2 hours, the mass of the sample would have decayed by half three times over. If one starts with 100 mg of the sample, then after three half-lives, there would be 100(0.5)³ = 12.5 mg of the sample remaining.

Thus, the correct answer choice here would be D.

Answer 2

I am here to confirm that it is D 12.5 bc most of the times brainly gives me wrong answers so yeah it is D