A radioactive sample has an initial activity of 10 μCi. After two half-lives, the activity is:
Correct answer: A. 2.5 μCi
- A. 2.5 μCi
- B. 5.0 μCi
- C. 7.5 μCi
- D. 10 μCi
Explanation
Activity A = A0 × (1/2)n, where A0 = 10 μCi and n = 2. Thus, A = 10 × (1/2)2 = 10 × 1/4 = 2.5 μCi.
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