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Worksheet 54 . Topic 12

Set A: cont.
9. There are 2.25 grams of iodine – 131 left after 40.35 days. How many
grams were in the original sample?

10. An unknown radioisotope that decays from 500 grams to 62.5 grams in
approximately 91 years.
Calculate the half-life of this radioisotope?

Teacher Preview Copy
Teacher Preview Copy
Identify the unknown radioisotope using Reference Table N.

11. A 50 g sample of a radioisotope decays to 12.5 grams in 14.4 seconds.
Calculate the half-life of this radioisotope?

Identify the radioisotope using Reference Table N.

12. In 7.38 days, a radioisotope undergoes 6 half-life periods.
What is the half-life of this radioisotope? Need Help? Study Book Pg 305 – 311 Set 22 - 28

Identify the radioisotope using Reference Table N

13. What fraction of a radioisotope will remain after 5 half-life periods?

14. What fraction of a sample of Hydrogen – 3 radioisotope will remain
unchanged after 49 years of decaying?

14
15. What fraction of C will remain unchanged after 17190 years.

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