If there are 200 atoms of an isotope present and the half-life of the isotope is 650 years, how long will it take for only 25 atoms of the isotope to remain?
A. 650 years
B. 650(1n2) years
C. Three half-years
D. 1950 years
D
It takes three half-lives for the sample to decay to 25 atoms. Since one half-life is 650 years, the total time it takes for the sample to decay to 25 atoms is 1950 years.
