An Open-Book 10-Minute Test of Lab 8 of PHYS 2C LAB
Radioactivity

You can only talk to your PARTNER(S) or the Teaching Assistant. If you have the leisure to show off your superior intellect, then I must follow the supervisor's instructions strictly: ask you all to do every thing required by the LAB MANUAL.

The NAME of EXAMINEE:

The NAME of EXAMINEE's partner:

The EXAMINEE's workstation:

RIGHT NOW, a stupid cow intakes 1.00´10¹² atoms of ¹³⁷Ba. From this lab we have determined the half-life time of ¹³⁷Ba is 2.55 minutes.

Question:

1. (0.5 POINT) How many hours after, would the quantity of ¹³⁷Ba inside that cow's body reduce to 5.00´10¹¹ atoms?

   ANSWER:

2. (0.5 POINT) Please prove that the percentage of the original activity of ¹³⁷Ba remains after 10 half-lives, i.e. 25.5 minutes, is 0.0977%.

   ANSWER: