Question

Francium decays with a half-life of 22 minutes. If we start out with 639 mg of francium,how much would remain after 2.7 hours?

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Answer 1

3.87 or 3.9 mg

Step-by-step explanation:

2.7h * 60mins = 162mins

number of 1/2 lives = 162/22= 7.364

amount remaining = 639(1/2)^7.364 = 3.8796

answer = 3.87 or 3.9