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Hints and answers for Half-life practice

Hints and answers for Half-life practice. Hints:. 1. How long will it take for 63/64 of a gold-198 sample to decay? Refer to chart to find # of half lives. Refer to left margin to find the length of one half life. Set up a proportion and solve for days.

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Hints and answers for Half-life practice

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  1. Hints and answers for Half-life practice

  2. Hints: • 1. How long will it take for 63/64 of a gold-198 sample to decay? Refer to chart to find # of half lives. Refer to left margin to find the length of one half life. Set up a proportion and solve for days. • 2. After 16.2 years, how much iron-55 is left if the sample size was 960g? Refer to left margin to find the length of one half life. Set up a proportion and solve for # of half lives. Refer to chart use # of half lives to find fraction remaining. Set up a proportion and solve for number of grams remaining.

  3. Hints: • 3. A fossil has a total mass of 512 g. If it contains 2 g of Thorium-230 and the rest is its decay element, how old is the fossil? Set up a fraction of grams left over total sample size; reduce the fraction Refer to chart to find # of half lives. Refer to left margin to find the length of one half life. Set up a proportion and solve for years. • 4. How many half-lives will it take for 512 becquerels of Mercury-203 to decay down to 1 atom? Set up a fraction of grams left over total sample size; reduce the fraction Refer to chart to find # of half lives.

  4. Hints: • 5. After 18.12 days, how much radioactive Calcium-47 will remain from a 48 gram sample? Refer to left margin to find the length of one half life. Set up a proportion and solve for # of half lives. Refer to chart use # of half lives to find fraction remaining. Set up a proportion and solve for number of grams remaining. • 6. A sample contains 35 g of Oxygen-15 and 1,085 g of F-15, its decay element. How old is the sample? Set up a fraction of grams left over total sample size; reduce the fraction Refer to chart to find # of half lives. Refer to left margin to find the length of one half life. Set up a proportion and solve for seconds

  5. Hints: • 7. Hooray! Jewelry for Christmas! On no! Your 128 g silver necklace is made from Silver-111. If 1 gram of radioactive silver is considered a safe amount, when would you be able to wear it? Why would you still not want to wear it after it was no longer radioactive? Set up a fraction of grams left over total sample size; reduce the fraction Refer to chart to find # of half lives. Refer to left margin to find length of 1 half life Set up proportion and solve for days If the silver is decaying through beta, what is the new element?

  6. Answers • 1. x = 16.176 days • 2. x = 5 grams • 3. x = 616,000 years • 4. Nine half lives • 5. x = 3 grams • 6. x = 611.2 seconds • 7. x = 52.15 days • Once it decays it is no longer silver. If it is beta it becomes cadmium and if it is alpha it becomes rhodium

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