The half-life of the radioisotope carbon-14 is 5730 years. How much C-14 will be left after 3 half-lives, if the initial amount is 100.0 g?

Question

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Answer 1

Each half-life reduces the amount by half, so after 3 half-lives, you are left with (1/2)*(1/2)*(1/2) of the initial amount.  Final amount is 

 

(100.0 g)(1/2)³ = (100.0 g) / 8 = 12.5 g