Initially a mixture of two radioactive sources contains the same number of nuclei of source A and source B.The half-life of A is 2 hours,and the half-life of B is 3 hours.What will be the ratio of remaining nuclei of A divided by remaining nuclei B after 12 hours? (Assume A does not decay into B or vice-versa.)
A)0.250
B)0.125
C)0.5
D)0.0625
E)None of these is correct.

Question

Quizplus · Accepted Answer

After 12 hours, source A will have gone through 6 half-lives (12/2), leaving (1/2)^6 = 1/64 of its original nuclei. Source B will have gone through 4 half-lives (12/3), leaving (1/2)^4 = 1/16 of its original nuclei. The ratio of remaining nuclei of A to B is (1/64) / (1/16) = 1/4 = 0.250.

Initially a Mixture of Two Radioactive Sources Contains the Same