The longest lived isotope of francium has a half-life of only:
A21 minutes
B21 hours
C21 days
D21 years
Answer & Solution
Correct answer: A. 21 minutes
1. Francium decays away very quickly.
2. Even its most stable isotope does not last long.
3. The half-life is only 21 minutes.
_Source: NCERT Class 11 Chemistry Part II, Unit 10, The s-Block Elements._
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