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OpenStudy (anonymous):
A sample of rock is found to contain 100 grams of a parent isotope. How many grams of the parent isotope will remain after two half-lives? Answer 50 100 75 25 @Earth Science
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OpenStudy (ash2326):
25grams
OpenStudy (trancenova):
2 half lives = the sample has been "halved twice". So 100/2 = 50, 50/2=25.
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