Activity and half-life calculations (including complex ones)

12 questions

1. Which of the following describes what is meant by a radioactive isotope having a half–life of 15 minutes?
2. How do the half–lives of different radioactive isotopes compare?
3. What effect does increasing the temperature have on the half–life of a radioactive isotope?
4. Starting with the longest, sort the following radioactive isotopes into order of decreasing half–life.
5. How does the half–life of a carbon–14 atom in a carbon monoxide (CO) molecule compare to its half–life in a carbon dioxide (CO₂) molecule?
6. A radioactive isotope has a half–life of 10 hours. Match each of the following fractions of the sample remaining to the correct amount of time that has passed.
7. The activity of a sample of a radioactive isotope is …
8. An activity of 100 becquerel (Bq) means …
9. Which of the following can be used to define what is meant by the half–life of a radioactive isotope?
10. Sodium–24 has a half–life of 15 hours. If a sample of sodium–24 originally has an activity of 500 Bq, what fraction of its original activity will remain after 30 hours?
11. After 42 days the activity of a sample of phosphorus–32 has decreased from 400 Bq to 50 Bq. What is the half–life of phosphorus–32?
12. The half–life of protactinium–234 is 6.75 hours. What percentage of the original sample will have decayed after 13.5 hours?

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