JAMB Physics 2012 Objective — Question 47
Question 47 of 50 from the Joint Admissions and Matriculation Board (JAMB) Physics 2012 Objective paper, with the correct answer and a full explanation.
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A piece of radioactive material contains 1000 atoms. If its half-life is 20 seconds, the time taken for 125 atoms to remain is
- A. 20 seconds
- B. 40 seconds
- C. 60 secondsCorrect
- D. 80 seconds
Explanation
1000→500 (20s)→250 (40s)→125 (60s). It takes 3 half-lives = 60 seconds for 125 atoms to remain.
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