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Worksheet 54: Half – Life calculations . Topic 12

Set A: Half-life problems Objective: To test your ability to solve half-life related problems

Solve the following half-life related problems. Use the following Reference Tables if necessary:
Reference Table N to get half-life and decay mode of a radioisotope

Reference Table T for half-life calculation equations.

1. In how many years would radium – 226 undergoes 5 half-life periods?

2. How many half-life periods will it take for a sample of Au to decay from
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original mass of 25 grams to a remaining mass of 1.56 grams?

3. In how many days will it take for a sample of P-32 to decay from an original
mass of 250 mg to a remaining mass of 62.5 mg?

4. How many milligrams of a 72 mg of a radioisotope will remain unchanged
after 4 half-life periods?
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5. How much of a 100-gram sample of Gold – 198 is left after 8.10 days. Need Help? Study Book Pg 305 – 311 Set 22 - 28

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6. How much of a 750-gram sample of K is left after 62 hours?

7. A 12 g sample of plutonium – 239 decays for 7.32 x 10 years.
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How many grams of the sample is left unchanged?

8. If there are 50 grams of a radioisotope remaining after 3 half-life period
of decaying, how many grams were in the original sample?

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