Half lives of two radioactive nuclei A and B are 10 minutes and 20 minutes, respectively. If, initially a sample has equal number of nuclei, then after 60 minutes, the ratio of decayed numbers of nuclei A and B will be:
A
9:8
B
1:8
C
8:1
D
3:8
Medium
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Updated on : 2022-09-05
Solution
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Correct option is A)
NA=NOAe−λt=2t/t21NOA=26NOA ∴ Number of nuclei decayed
=NOA−26NOA=6463NOA
NB=NOBe−λt=2t/t21NOB=23NOB
∴ Number of nuclei decayed =NOB−23NOB=87NOB
Since NOA=NOB
∴ ratio of decayed numbers of nuclei A&B=64×7NOB63NOA×8=89