question_answer 56)

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

t(h)	0	1	2	3	4
	100	35.36	12.51	4.42	1.56

(i) Plot the graph of R versus ( and calculate half-life from the graph. (ii)Plot the graph of Inversus (and obtain the value of half-life from the graph.

Answer:

                  In Table 8.1, we have listed R  and loge (R/R0) of a radioactive nuclide at different time intervals. TABLE 8.1            

t(h)	0	1	2	3	4
	100	35.36	12.51	4.42	1.56
	___	-1.04	-2.08	-3.11	-4.16

          (i) When we plot the graph of R versus t, we obtain an exponential curve as shown in Fig.8(EP).5(a). From the graph, we find that activity R reduces to 50% in t= OA 40 minutes. This gives us half life of the nuclide. (ii) Fig. 8(EP).5(b) shows the graph of loge (R/R0) versus t. Slope of this graph = -. From the graph, Half life,