A radioactive sample has 800 undecayed nuclei. How many remain after 3 half-lives?
Answer and explanation
Correct answer: A.
- Step 1: Each half-life halves the number of nuclei: .
- Step 2: .
Answer
.
Why not the others: : The count was divided by the number of half-lives. : One half-life too few was used. : The number that decayed was given.
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