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A radioactive element disintegrates for a time interval equal to its mean life. The fraction that has disintegrated isA. (a) `1/e`B. (b) `1-1/e`C. (c) `0.693/e`D. (d) `0.693(1-1/e)` |
Answer» Correct Answer - B Number of atoms disintegrated, `N=N_0(1-e^(-lambdat))` `:.` `N/N_0=1-e^(-lambdat)` At `t=`one mean life `=1/lambda` `N/N_0=1-e^-1=1-1/e` |
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