Half-Life

What is 'half-life'?

• The age determined by the things around it.

• The age of an igneous rock.

• The age determined by radioactive dating.

• The time it takes for 1/2 of the radioactive atoms to decay in an element.

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NGSS.HS-PS1-8

The half-life of Zn-71 is 2.4 minutes. If one had 100.0g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

Os-182 has a half-life of 21.5 hours. How many grams of a 10.0 gram sample would have decayed after exactly three half-lives?

After 24.0 days, 2.00 milligrams of an original 128.0 milligram sample remain. What is the half-life of the sample?

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NGSS.HS-PS1-8

At time zero, there are 10.0 grams of W-187. If the half-life is 24 hours, how much will be present at the end of one day? Two days? Seven days?

100.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How much time will have elapsed when 6.25 grams remains?

What is the half-life of the decay curve?

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NGSS.HS-PS1-8

What is the half-life of Carbon-14 according to the curve?

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NGSS.HS-PS1-8

Pd-100 has a half-life of 4 days. If one had 120g at the start, how much would be present after 20.0 days?

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NGSS.HS-PS1-8

Fermium-253 has a half-life of 0.334 seconds. A radioactive sample is considered to be completely decayed after 10 half-lives. How much time will elapse for this sample to be considered gone?

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NGSS.HS-PS1-8