The activity of a radioactive substance changes from 8000 Bq to 1000 Bq in 12 days. What is the half-life of the radioactive substance?
Correct answer: A. 4 days
- A. 4 days
- B. 6 days
- C. 2 days
- D. 3 days
Explanation
Nt = No (½)t/2Here, Nt is the amount at time t, No is the initial amount of radioactive substance and T is the half-life. Here, No = 8000 Bq, Nt/2 = 1000 Bq 1000 = 8000 * (½)n 1000/8000 = (½)n⅛ = (½)n (½)3 = (½)nBy equating, n = 3.It means that after 3 half-lives, the activity of the substance changes from 8000 Bq to 1000 Bq.According to the given data, 3 half-lives are equivalent to 12 days. 3 t1/2 = 12 days 1 t1/2 = 12/3 = 4 days.Hence, option A is the correct option.
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