The half-life of radium is about 1600 years. Of 100 grams of radium existing now, 25 gram will remain unchanged after:
Correct answer: B. 3200 years
- A. 2400 years
- B. 3200 years
- C. 6400 years
- D. 4800 years
Explanation
50 g of radium will remain unchanged after 1 half life and 25 g of radium will remain unchanged after 2 half lives. As half life of radium is 1600 years so 25 g of it will remain after 2×1600=3200 years.
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