It was your turn to straighten up the lab, but, oh great, someone spilled a solution on the floor for you to clean up and apparently left without saying a word. Upon a closer look, you notice an overturned bottle, empty, from which the mixture drained, and it has a radiation symbol on it. Further, the solution smeared the isotope name, so do not know what it is. The chart records show that the following isotopes were kept in the lab: 22Na, 54Mn, 57Co, 60Co, 88Y, 89Sr, 133Ba, 137Cs, 141Ce, 168Tm, and 241Am. You have only a Geiger-Muller counter at hand. At first count, the emissions are below 1 mR/hr, so you are not in immediate danger. Next, you take the following 1-minute counts spaced at 48 hours apart.
i. Which isotope do you suspect was in the bottle?
ii. How sure are you? Explain your reasoning.
Measurement number Counts
1 8754
2 8517