The half-life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after:
Correct answer: B. 3200 years
- A. 2400 years
- B. 3200 years
- C. 6400 years
- D. 4800 years
Explanation
Two half lives later, 100g of gamma rays will be reduced to 25g. 100/2² = 25 The half life of Radium = 1600 yearsTime taken = 2×1600 = 3200 years
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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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