10 questions

- 1. Open EndedThe half-life of radon-222 is 3.8 days. How much of a 100. g sample is left after 15.2 days?
- 2. Open EndedCarbon-14 has a half-life of 5,715 years. If a sample contains 70 mg originally, how much is left after 17,190 years?
- 3. Open EndedHow much of a 500. g sample of potassium-42 is left after 62 hours? The half-life of potassium-42 is 12.4 hours.
- 4. Open EndedThe half-life of cobalt-60 is 5.26 years. If 50.0 g are left after 15.8 years, how many grams were in the original sample?
- 5. Open EndedIf 100 g of gold-198 decays to 6.25 g in 10.8 days, what is the half-life of gold-198?
- 6. Open EndedWhat is the half-life of a 100.0 g sample of nitrogen-16 that decays to 12.5 g of nitrogen-16 in 21.6 s?
- 7. Open EndedAll isotopes of technetium are radioactive, but they have widely varying half-lives. If an 800.0 g sample of technetium-99 to 100.0 g of technetium-99 in 639,000 y, what is its half-life?
- 8. Open EndedA 208. g sample of sodium-24 decays to 13.0 g of sodium-24 within 60.0 h. What is the half-life of this radioactive isotope?
- 9. Open EndedIf half-life of iodine-131 is 8.10 days, how long will it take a 50.00 g sample to decay to 6.25 g?
- 10. Open EndedThe half-life of hafnium-156 is 0.025 s. How long will it take a 500. g sample to decay to ¼ its original mass?
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