`.^(90)Sr` decays to `.^(90)Y` by `beta` decay with a half-life of `28 – InterviewSolution

InterviewSolution

1.	`.^(90)Sr` decays to `.^(90)Y` by `beta` decay with a half-life of `28` years. `.^(90)Y` decays by `beta`-to `.^(90)Zr` with a half-life of `64h`. A pure sample of `.^(90)Sr` is allowed to decay. What is the valued of `(N_(Sr))/(N_(y))` after (a) `1h` (b) `10` years ?
Answer» `N_(sr)=N_(Sr)^(0)r^((-lambda_(sr)t))` ....(1) `N_(y)=(lambda_(sr)N_(sr)^(0))/(lambda_(y)-lambda_(sr))[e^((lambda_(sr)t))-e^((-lambda_yt))]` .......(2) Dividing the two equations `(N_(y))/(N_(sr))(lambda_(sr))/(lambda_(y)-lambda_(sr))[1-e^((-lambdat))(lambda_(sr)-lambda_(y))t]` `lambda_(sr)=0.693//(28xx365xx24)=2.825xx10^(-6)h^(-1)` `lambda_(y)=0.693//64=0.0108 h^(-1)` (a) For `t=1h` and using the values for the decay constant `N_(sr)//N_(y)=3.56xx10^(5)` (b) For `t=10 "year", N_(sr)//N_(y)=3823`

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`.^(90)Sr` decays to `.^(90)Y` by `beta` decay with a half-life of `28` years. `.^(90)Y` decays by `beta`-to `.^(90)Zr` with a half-life of `64h`. A pure sample of `.^(90)Sr` is allowed to decay. What is the valued of `(N_(Sr))/(N_(y))` after (a) `1h` (b) `10` years ?