Question

The half-life of ²⁷Mg is 9.50 min.

(a) Initially there were 4.10 × 10¹²²⁷Mg nuclei present. How many ²⁷Mg nuclei are left 25.5 min later? Please give your answer to 2 significant figures.

b) Calculate the ²⁷Mg activities (in Ci) at t = 0 and t = 25.5 min.

t= 0 __Ci

t= 25 __ Ci

Answer 1

In order to calculate the number of nuclei present ,the information about the half decay is needed.The half life of this decay follows the first order kinetics. So,Here, N(f ) is the number of nuclei remaining after 25.5 min and N(o) is the number of nuclei at the initial ( t= 0 min)

h equoAm fore he Arst ordir decoy 41255 t½-9.50 mim No -4 10 Xiol27 muum 0.693 x No 0.693 -X 4.10 χ1012 0.69 3