Radioactive 90Sr has a half-life of 30 years. What percent of a sample of 90Sr will remain after 60 years?
Correct answer: C. 25%
- A. 0%
- B. 50%
- C. 25%
- D. 75%
Explanation
After 60 years, 2 half lives will have passed so after first half life 50% of sample will be left and after second half life , half of the sample will remain that is 25% (half of 50%).
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