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InterviewSolution
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One gram ofo a radioactive substance disintegrates at the rate of `3.7 xx10^(10)` disintegarations per second. The atomic mass of the subsatnce is `226`. Calculate its mean life. |
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Answer» Correct Answer - `7.194 xx10^(10)s` Given that activity of substance is `A_(c)=3.7 xx10^(10)dps` The number of atoms in `1 g` of substance, `N=(1 xx 6.023 xx10^(23))/(226) =2.66 xx10^(21)"atoms"` If `lambda` is the decay constant of the substance, we know that activity is given by `A_(C) =lambda N` or `lambda =(A_(c))/(N)` `=(3.7 xx10^(10))/(2.66 xx10^(21)) s^(-1)=1.39 xx 10^(-11) s^(-1)` Thus, mean life of the radioactive substance is `T_(m) =(1)/(lambda)=(1)/(1.39 xx10^(-11)) =7.194 xx 10^(10)s`. |
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