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Radioactivity Worksheet
2. If the half-life of a radioactive material is 500 years, what part of the radioactive element will still remain after
1500 years?
(1) 1/2
(2) 1/4
(3) 1/8
(4) 1/16
3. As the mass of a Uranium-238 sample increases, it’s half-life:
(1) increases
(2) decreases
(3) remains the same
4. If you start off with 100 grams of Uranium-238, how much would you have left after 4 half-lives?
What if you started off with 200 grams of Uranium-238?
What if you started with 500 grams of Uranium-238?
5. Carbon-14 has a half-life of 5,700 years and decays to produce the daughter element Nitrogen-14.
If you start off with 100 grams of Carbon-14, how much Nitrogen-14 will exist after 17,100 years?
6. If a sample contains 50g of Carbon14 and 50g of Nitrogen14, how many half-lives has it undergone?
7. If a sample contains 25g of Carbon14 and 75g of Nitrogen14, how many half-lives has it undergone?
8. If a sample contains 25g of Carbon14 and 175g of Nitrogen14, how many half-lives has it undergone?
9. How old is a bone in which the Carbon14 in it has undergone 3 half-lives?
10. What percent of Carbon14 is left after 5 half-lives?
11. What happens to the amount of Nitrogen14 as the Carbon14 decays?
12. If a 20g of Carbon14 has a half-life of 5,700 years, what would be the half-life of a 40g sample?
Answers
2. If the half-life of a radioactive material is 500 years, what part of the radioactive element will still remain after
1500 years?
(1) 1/2
(2) 1/4
(3) 1/8
(4) 1/16
3. As the mass of a Uranium-238 sample increases, it’s half-life:
(1) increases
(2) decreases
(3) remains the same
4. If you start off with 100 grams of Uranium-238, how much would you have left after 4 half-lives? 6.25g
What if you started off with 200 grams of Uranium-238? 12.5g
What if you started with 500 grams of Uranium-238? 31.25g
5. Carbon-14 has a half-life of 5,700 years and decays to produce the daughter element Nitrogen-14.
If you start off with 100 grams of Carbon-14, how much Nitrogen-14 will exist after 17,100 years?
100-12.5= 87.5g
6. If a sample contains 50g of Carbon14 and 50g of Nitrogen14, how many half-lives has it undergone? one
7. If a sample contains 25g of Carbon14 and 75g of Nitrogen14, how many half-lives has it undergone? two
8. If a sample contains 25g of Carbon14 and 175g of Nitrogen14, how many half-lives has it undergone? three
9. How old is a bone in which the Carbon14 in it has undergone 3 half-lives? 17100 years
10. What percent of Carbon14 is left after 5 half-lives? 3.125%
11. What happens to the amount of Nitrogen14 as the Carbon14 decays? It increases
12. If a 20g of Carbon14 has a half-life of 5,700 years, what would be the half-life of a 40g sample? The same