The half-life of phosphorus-33 is 25 days.How much of a 128-g sample will remain after 160 days?

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Quizplus · Accepted Answer

The half-life of a substance is the amount of time it takes for half of the substance to decay. After one half-life, half of the original amount remains. After two half-lives, half of the remaining amount remains, or one-fourth of the original amount. After three half-lives, one-eighth of the original amount remains, and so on.In this case, the half-life of phosphorus-33 is 25 days. After 160 days, which is 160/25 = 6.4 half-lives, the amount of phosphorus-33 remaining will be 1/2^6.4 = 1/64 of the original amount. Therefore, the amount of phosphorus-33 remaining will be 128 g * 1/64 = 2 g.

The Half-Life of Phosphorus-33 Is 25 Days