The half-life of Iodine-131 is 8 days. If a sample has initial activity of 100 counts per minute, after 24 days the activity will be: MCQ with Answer and Explanation
The half-life of Iodine-131 is 8 days. If a sample has initial activity of 100 counts per minute, after 24 days the activity will be:
A. 25
B. 12.5
C. 6.25
D. 50
Answer: Option B
Solution (By JKExamLibrary)
Number of half-lives = 24/8 = 3. Fraction remaining = (1/2)³ = 1/8. Activity = 100 × 1/8 = 12.5 counts per minute. Radioactive decay is exponential. After 1 half-life: 50, 2: 25, 3: 12.5. This isotope is used in thyroid treatment.
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