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Activity falls from 800 Bq to 100 Bq in 9 days. What is the half-life?
A9 days
B1 day
C3 days
D4.5 days
Answer & Solution
Correct answer: C. 3 days
800 to 100 is three halvings, so 9 days is three half-lives, giving 3 days each.
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