WAEC Physics 2025 Objective — Question 29
Question 29 of 51 from the West African Examinations Council (WAEC) Physics 2025 Objective paper, with the correct answer and a full explanation.
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A radioactive substance of mass 512.0g decays to 64.0g. Determine the number of half-lives involved in the decay.
- A. 8
- B. 6
- C. 4
- D. 3Correct
Explanation
512g → 256g → 128g → 64g corresponds to 3 half-lives, since (1/2)³ = 64/512 = 1/8.
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