InterviewSolution
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InterviewSolution
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If `10%` of a radioactive material decays in `5` days, then the amount of original material left after `20` days is approximately.A. `60%`B. `65%`C. `70%`D. `75%` |
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Answer» Correct Answer - B (b) we have `N=N_(0e^(-lamdat))` `therefore 0.9 N_(0)=N_(0)e^(-lamda xx5)implies 5lamda =log _(e) "" (1)/(0.9)` and ` xN_(0)e^(-lamda xx20)implies 20 lamda =log_(e) ((1)/(x)) ` Dividing Eq. (i) by Eq (ii) ,we get `(1)/(4)=(log_(e)(1//0.9))/(log _(e) (1//x))=(log_(10)(1//0.9))/(log _(10)(1//x))=(log_(10).9)/(log_(10)x)` `implies log _(10)x=4log_(10)0.9implies x=0.658=65.8% ~=65%` |
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