Starting with a sample of pure ⁶⁶Cu, 7/8 of it decays into "Zn" in 15 minutes. The corresponding half-life is:
Correct answer: C. 5 minutes
- A. 15 minutes
- B. 7.5 minutes
- C. 5 minutes
- D. 3.75 minutes
Explanation
If 7/8 has decayed, 1/8 remains. The fraction remaining is (1/2)ⁿ, where n is the number of half. lives. Since (1/2)³ = 1/8, three half. lives have passed in 15 minutes. Therefore, one half-life is 15/3 minutes = 5 minutes.
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