Name: ______
Nuclear Problems W.S. #2
1. The half-life of radon – 222, a radioactive gas of concern as a health hazard in some homes, is 3.823 days. What is the decay constant () of this gas?
2. Sr – 90 has a half-life of 28.1 years. If you start with a 3.76 mg sample, how much of it will be left after 168.6 years? How long will it take to decay to 1/8 of its original value?
3. What is the half-life of iron – 59, a radioisotope used medically in the diagnosis of anemia, if a sample initially decays at 16,800 disintegrations/min and after 28.0 days it undergoes 10,860 dpm.
4. The decay constant of thallium – 201, a radioisotope used for parathyroid imaging, is 0.228/days. What is the half-life of thallium – 201? How long would it take to reach 1/8 of its original value?
5. The decay constant () for sodium – 24, a radioisotope used medically in blood studies, is 4.63 x 10-2/hr. What is the half-life of Na?
6. Tritium, Hydrogen – 3, has a half-life of 12.3 years. If you start with a 2.6 mg sample, how much of it will be left after 36.9 years? How long will it take to decay to 1/8 of its original value?
7. A sample of argon – 37 undergoes 8540 dpm initially but undergoes 6990 dpm after 10.0 days. What is the half-life of argon – 37 in days? How long will it take to decay to ¼ of its original value?
8. Argon – 37 has a half-life of 34.7 days. If you start with a 4.27 mg sample, how much of it will be left after 0.380 years? How long will it take to decay to 1/32 of its original value?