A radioactive substance has a half-life of 60 min. During 3 hours, the fraction of the substance that has decayed is:
Show Hint
- 1/8
- 7/8
- 1/4
- 3/4
The Correct Option is B
Solution and Explanation
Fraction remaining $f = (1/2)^{n}$, where $n$ is the number of half-lives.
Step 2: Analysis
3 hours = 180 min. Number of half-lives $n = 180/60 = 3$.
Fraction remaining $= (1/2)^{3} = 1/8$.
Step 3: Conclusion
Fraction decayed $= 1 - 1/8 = 7/8$.
Final Answer: (B)
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