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Question

A sample of radioactive material A, that has an activity of 10mCi(1Ci=3.7×1010decays/s), has twice the number of nuclei as another sample of a different radioactive maternal B which has an activity of 20mCi. The correct choices for half-life of A and B would then be respectively :
  1. 20 days and 5 days
  2. 10 days and 20 days
  3. 5 days and 10 days
  4. 10 days and 40 days

A
20 days and 5 days
B
10 days and 20 days
C
10 days and 40 days
D
5 days and 10 days
Solution
Verified by Toppr

The correct option is A 20 days and 5 days
Activity A=λN
For A 10=(2N0)λA
For B 20=N0λB
λB=4λA(T1/2)A=4(T1/2)B

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