A radioactive sample has a half-life of . If the initial activity of the sample is , what will be its activity after ?
Answer and explanation
Correct answer: D.
- Step 1: Determine the number of elapsed half-lives: half-lives.
- Step 2: The activity decays by a factor of : .
- Step 3: Calculate: .
Answer
.
Why not the others: corresponds to 2 half-lives (); corresponds to 4 half-lives (); assumes linear decay.
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