Question

radioisotope actinium 225 has half life of 10 days, I begin with 16 kg of this isotope, how much will remain after 40 days?

Answer 1

`N(t)=N_(0)((1)/(2))^\frac{t}{\tau_{_(1)/(2)}}}\\\\ N_(0)=16kg\\ t=40days\\ \tau_{_(1)/(2)}}=10days\\\\\\ N(t)=16kg*((1)/(2))^{(40)/(10)}=16kg*(1)/(16)=1kg`