Half Life Worksheet – This is extra practice for the test. It is not to be turned in. See answer sheet to check your work.
1) Fluorine-21 has a half life of approximately 15 seconds. How much of the original 5 g sample would remain after 60
seconds?
0.6 g
2) Iodine-131 has a half life of 8 days. Your original sample has a mass of 45 g. How much of the original sample would
remain at the end of 32 days?
2.8 g
3) The half-life of chromium-51 is 28 days. If the sample contained 510 grams, how much chromium would remain after
56 days?
255 g
4) The half life of Uranium-238 is 4.5 billion years and the age of earth is 4.5 X 10 9 years. How much of a 25 g sample
of Uranium-238 will be that was present when Earth was formed still remains?
13 g
5) The half life of iodine-125 is 60 days. How much of a 4100 g sample is left after 360 days?
64 g
6) Titanium-51 decays with a half life of 30 minutes. How much of a 25 g sample would be left after one hour?
13 g
7) The half life of radium-226 is 1602 years. How much of a 1000 g sample would remain after 9612 years?
500 g