Given
Half life of tritium is
[tex]t_{\frac{1}{2}}=12.3\text{ years}[/tex]The sample is reduced to 10% of its original value.
To find
How many years will have elapsed when the radioactivity of a tritium sample has decreased to 10 percent of its original value?
Explanation
The activity is given by
[tex]\begin{gathered} A=A_oe^{-\lambda t} \\ \Rightarrow0.1A_o=A_oe^{-\frac{0.693}{t_{\frac{1}{2}}}t} \\ \Rightarrow ln(0.1)=-\frac{0.693}{1.23}t \\ \Rightarrow-2.302=-\frac{0.693}{1.23}t \\ \Rightarrow t=4.08 \end{gathered}[/tex]Conclusion
The time taken is 4.08 years
