Question

The activity R of an unknown nuclide is measured at hourly intervals. The results found are tabulated as follows :

t(h)	0	1	2	3	4
R (MBq)	100	35.36	12.51	1.56	1.56

Answer 1

(i) t_1/2 = 0.693 / 1.05 = 39.6 or appro. 40 min

(ii) slope of graph = -λ

λ = -[-4.16 + 3.11/1] = 1.05 h

t_1/2 = 0.693/1.05 = 39.6 or appro. 40 min