The half-life of radium is about 1600 years.If a rock initially contains 1 g of radium, the amount left after 8000 years will be about:
A)200 mg
B)63 mg
C)31 mg
D)16 mg
E)less than 1 mg

Question

Quizplus · Accepted Answer

The half-life of radium is 1600 years, so after 8000 years (which is 5 half-lives), the amount of radium will be reduced to (1/2)^5 of the original amount. (1/2)^5 = 1/32, so 1 g of radium will be reduced to 1/32 g, which is approximately 31 mg.

The Half-Life of Radium Is About 1600 Years