# A sample of radioactive material A, that has an activity of 10m Ci(l Ci=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 choice for hall-lives of A and B an would then be respectively: a. 20 days and 5 days b. 20 days and 10 days c. 5 days and 10 days d. 10days and 40days

## Question ID - 50055 :- A sample of radioactive material A, that has an activity of 10m Ci(l Ci=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 choice for hall-lives of A and B an would then be respectively: a. 20 days and 5 days b. 20 days and 10 days c. 5 days and 10 days d. 10days and 40days

3537

Activity A= N

For A    10=(2N0) A

For B     20=N0 B

B=4 A (T1/2)A=4(T1/2)B

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Consider a tank made of glass (reiractive index 1.5) with a thick bottom.  It is filled with a liquid of refractive index ., A student finds that, irrespective of what the incident angle i(see figure0 is for a beam of light entering the liquid, is never reflected from the liquid glass interface happen, the minimum value of  is:

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