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 :
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Question

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 :

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G1 Physics · Accepted Answer

Step 1: Use N(t) = N₀ exp(−λt), A = λN and T₁/₂ = ln2/λ. Step 2: For two samples, write the decay law separately and equate the required activities/numbers. Final: A: 9 : 8.