InterviewSolution
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InterviewSolution
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Two radioactive substances `A` and `B` have half lives of `T` and `2T` respectively. Samples of `a` and `b` contain equal number of nuclei initially. After a time `4T`, the ratio of the number of undecayed nuclei of `A` to the number if undecayed nuclei of `A` to the number of undeacyed nuclei of `B` isA. `1 : 4`B. `1 : 2`C. `2 : 1`D. `4 : 1` |
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Answer» Correct Answer - A `t = 4T,(T_(1//2))_(A) = T, (T_(1//2))_(B) = 2T` `A: t = n(T_(1//2))_(A) rArr 4T = nT rArr n = 4` `N_(A) = N_(0) ((1)/(2))^(n) = N_(0) ((1)/(2))^(4) = (N_(0))/(16)` `B: t = n(T_(1//2))_(B) rArr 4T = n xx 2T rArr n = 2` `N_(B) = N_(0)((1)/(2))^(n) = N_(0)((1)/(2))^(2) = (N_(0))/(4)` `(N_(A))/(N_(B)) = (N_(0)//16)/(N_(0)//4) = (1)/(4)` |
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