Atoms And Nuclei Question 369

Question: After 150 days, the activity of a radioactive sample is 5000 dps. The activity becomes 2500 dps after another 75 days. The initial activity of the sample is

Options:

A) 20000 dps

B) 40000 dps

C) 7500 dps

D) 10000 dps

Show Answer

Answer:

Correct Answer: A

Solution:

  • Activity of sample becomes 2500 from 5000 in 75 days therefore its half-life is 75 days, so $ R=\frac{R_{0}}{{{2}^{\frac{150}{75}}}}=5000\Rightarrow R_{0}=5000\times 4=20,000 $


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