The half-life of iodine-131 is 8 days. If a medical treatment involves a dose of 400 mg of iodine-131, how much of the isotope remains after 32 days?

Name: The half-life of iodine-131 is 8 days. If a medical treatment involves a dose of 400 mg of iodine-131, how much of the isotope remains after 32 days?
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Quizplus · Accepted Answer

After 32 days, which is 4 half-lives of iodine-131 (8 days per half-life), the amount remaining is (1/2)^4 = 1/16 of the original amount. Therefore, 400 mg * 1/16 = 25 mg remains.

The Half-Life of Iodine-131 Is 8 Days