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The half-life of Au-198 is 2.7 days When there are 800 atoms of Au-198 in a sample a scientist starts a stopwatch The scientist stops the stopwatch at 8.1 days there are atoms of Au-198 re?
CasandRAWR
its 100
Wiki User
∙ 15y ago
At 2.7 days, half of the 800 atoms (400 atoms) would have decayed. At 8.1 days, three half-lives have passed, so only ( \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = \frac{1}{8} ) of the original sample remains. Therefore, there are 100 atoms of Au-198 remaining in the sample after 8.1 days.
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