The quantity of uranium is 400g, the amount of uranium left after 3 half lives is:
Correct answer: B. 50g
- A. 25g
- B. 50g
- C. 100g
- D. 200g
Explanation
After every half life, the amount of uranium halves. Following this idea, after the first half life, the amount of uranium drops from 400g to 200g. After the second half of life, it drops to 100g. And finally after the third half life, what remains is 50 grams of uranium.
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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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