1. Tardigrade
  2. Question
  3. Physics
  4. After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activity of the sample in dps is

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activity of the sample in dps is

IIT JEEIIT JEE 2004

Solution:

Activity reduces from 6000 dps to 3000 dps in 140 days. It implies that'half-life of the radioactive sample is 140 days. In 280 days (or two half-lives) activity will remain $\frac{1}{4}$ th of the initial activity. Hence, the initial activity of the sample is $4\times6000 dps = 24000 dps$ Therefore, the correct option is (d).