The Mean Life (Time Constant) of Radon-222 Is 5

question 157

Multiple Choice

The mean life (time constant) of radon-222 is 5.526 d. If a sample of radon initially contains 6.00 × 10⁸ radon atoms, how many of them are left after 10.0 d?

• A) 9.82 × 10⁷
• B) 7.67 × 10⁷
• C) 8.34 × 10⁸
• D) 7.29 × 10⁸
• E) 8.56 × 10⁸

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