A sample of Pb-212 is showing 1000 disintegrations per second. Its activity is counted every 6 hours and the results are displayed in the table below.

• Use Excel to plot the data on a linear scale; observe the logarithmic trend.
• Next, take the log of the second column and draw a semilog plot.
• It should be a straight line; calculate its slope.
• It should give you the decay constant of Pb-212.

Calculate the half-life of Pb-212 and compare with the chart of nuclides value.

Time (hrs)	Count
0	1000
6	677
12	458
18	310
24	210
30	142
36	96
42	65
48	44
54	30
60	20
66	14
72	9
78	6
84	4