The count rate of nuclear radiation coming from a radioactive sample containing 128I varies with time as follows.

(a) Plot ln(R0/R) against t.


(b) From the slope of the best straight line through the points, find the decay constant λ.


(c) Calculate the half-life t1/2.


We take R˳ at time t=t˳ i.e. R˳= 30× 109 s-1

(a)







(b) As ln(R0/R) = λt


So, slope of this curve will give the value of λ



(c)


1