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After 280 days, the activity of a radioa...

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

A

`6000`

B

`9000`

C

`3000`

D

`24000`

Text Solution

Verified by Experts

The correct Answer is:
D
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 for two half-lives) activity ill remain `1/4` th of the initial activity. Hence the initial activityof the sample is `4xx6000 dps=24000dps`
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ALLEN -SIMPLE HARMONIC MOTION-Exercise-05(B)
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