Adapted by Nelson Nuñez-Rodriguez
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By David W. Ball
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| QUESTION | ANSWER |
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1. Do all isotopes have a half-life? Explain your answer. |
1. Only radioactive isotopes have a half-life. |
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3. How long does it take for 1.00 g of palladium-103 to decay to 0.125 g if its half-life is 17.0 d? |
3. 51.0 d |
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5. It took 75 y for 10.0 g of a radioactive isotope to decay to 1.25 g. What is the half-life of this isotope? |
5. 25 y |
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7. The half-live of americium-241 is 432 y. If 0.0002 g of americium-241 is present in a smoke detector at the date of manufacture, what mass of americium-241 is present after 100.0 y? After 1,000.0 y? |
7. 0.000170 g; 0.0000402 g |
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9. Explain why the amount left after 1,000.0 y in Exercise 7 is not one-tenth of the amount present after 100.0 y, despite the fact that the amount of time elapsed is 10 times as long. |
9. Radioactive decay is an exponential process, not a linear process. |
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11. An artifact containing carbon-14 contains 8.4 × 10−9 g of carbon-14 in it. If the age of the artifact is 10,670 y, how much carbon-14 did it have originally? The half-life of carbon-14 is 5,730 y. |
11. 3.1 × 10−8 g |