Radio active decay reactions follow first order rate kinetics.
a) The half life and decay constant for radio active decay reactions are related by the equation:



Where k is the decay constant
b) Finding out the decay constant for the decay of C-14 isotope:



c) Finding the age of the sample :
35 % of the radiocarbon is present currently.
The first order rate equation is,
![[A] = [A_(0)]e^(-kt)](https://img.qammunity.org/2019/formulas/chemistry/college/98iebuskd7hhnezz5m9c7sj64fo61ye5c1.png)
![([A])/([A_(0)]) = e^(-kt)](https://img.qammunity.org/2019/formulas/chemistry/college/qhnrm4xg0lpz77644e6l4vpwlps3szn6ki.png)


t = 7923 years
Therefore, age of the sample is 7923 years.