The sample of radioactive element decayed after 5 half-lives is:
Correct answer: C. 31/32No
- A. 1/32No
- B. No/31-No/32
- C. 31/32No
- D. No/32-No/31
Explanation
Np/No = (2n - 1)/ 2n= (25 - 1)/25 = 31/32
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About Half-life and Rate of Decay
Half-life is the time required for half the unstable nuclei in a sample to decay, and it remains constant for a particular radioactive nuclide. Questions use the exponential decay law, decay constant, activity, remaining quantity and mean life. Radioactive decay is random for individual nuclei but predictable for large samples.
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