During nuclear explosion, one of the products is `.^(99)Sr` with half`-` life of `28.1 `years. If `1 mug` of `.^(90)Sr` was absorbed in the bones of a newly born baby instead of calcium, how much of its will remain after 10 years and 60 years if it is not lost metabolically.

Explanation

To solve the problem of how much of the radioactive isotope \( ^{90}Sr \) will remain after 10 years and 60 years, we will follow these steps:

### Step 1: Determine the decay constant \( k \)
The half-life (\( t_{1/2} \)) of \( ^{90}Sr \) is given as 28.1 years. The relationship between half-life and the decay constant is given by the formula:

\[ t_{1/2} = \frac{\ln 2}{k} \]
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