Question

3) Gold-198 has a half-life of 2.7 days. How much of a 662.5 mg gold-198 sample will remain after 13.5 days?

Answer 1

All nuclear reactions are of first order reactions.

For a first order reaction rate constant ,

Also   

Where

N_o = initial mass of Gold-198= 662.5 mg

N_t = mass of Gold-198 left after time t = ?

t = time taken = 13.5

Plug the values we get

                                  

                                       

                                      

Therefore 20.7 mg gold-198 sample will remain after 13.5 days