131 I an isotope of iodine Z53 used for medical purposes has

^131 I, an isotope of iodine (Z=53) used for medical purposes, has a half-life of 8.025 days. It decays by beta^- emission. a)What is the average lifetime of a^131 I nucleus? b)What is the decay constant of^131 I?

Solution

t_1/2=8.025 days. Now t_1/2=ln(2)/lambda. Where lambda is the decay constant. So lambda=ln(2)/8.025 day^(-1)=0.0864. And the mean life is tau=1/lambda=11.58 days.

-Avi(IST-10:06pm, 1/4/16)