A sample has 64 radioactive nuclei. How many remain undecayed after 3 half-lives?
Answer and explanation
Correct answer: B. 8 nuclei
- Step 1: After half-lives . Answer: 8 nuclei. Why not the others: 21 nuclei: divides by the number of half-lives instead of . 10 nuclei: divides by twice the number of half-lives. 16 nuclei: uses one half-life too few.
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