For a radioactive isotope obeying first-order kinetics, what fraction of the original sample remains undecayed after 4 half-lives?
Answer and explanation
Correct answer: D.
- Step 1: In first-order radioactive decay, the fraction of nuclei remaining after half-lives is .
- Step 2: Given half-lives.
- Step 3: Compute: .
Answer
.
Why not the others: corresponds to 3 half-lives; corresponds to 5 half-lives; corresponds to 6 half-lives.
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