WAEC Physics 2025 Objective — Question 21
Question 21 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 element of mass 16g was isolated and stored. It was discovered that after 40 days only 1g of the element remained undecayed. Calculate the half-life of the element.
- A. 2.5days
- B. 5.0days
- C. 10.0daysCorrect
- D. 15.0days
Explanation
16g → 8g → 4g → 2g → 1g represents 4 half-lives. T½ = t/n = 40/4 = 10 days.
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