1. An archaeologist finds the 14C in a sample of of material to be decaying at 1
ID: 249641 • Letter: 1
Question
1. An archaeologist finds the 14C in a sample of of material to be decaying at 107 counts per second. A modern sample of the same material decays at 151 counts per second. The half-life of is 5730 years. How old is the sample?
17,000 years
8990 years
8530 years
6230 years
2. Radon-222 undergoes an alpha decay to become polonium-218. This reaction is an intermediate in a decay series that begins with uranium-238 and ends in lead-206.
A 1.0-gram sample of pure uranium-238 is sealed in a container at time = 0 years. To calculate the amount of radon-222 present in the container at any moment in the future, what is the minimum amount of information that must be known?
-the half-life of each decay reaction in the series from uranium-238 to polonium-218
-the half-life of each decay reaction in the series from uranium-238 to lead-206
-the longest half-life in the series from uranium-238 to radon-222
-the half-life of each decay reaction in the series from uranium-238 to radon-222
3. For two small nuclei to fuse, their kinetic energies must be great enough to overcome ________
-the electrical attraction between them and their electrons
-the strong nuclear force that attracts them together
-the electrical repulsion of their positive charges
4. The decay constant of a radioactive nuclide is 3.1 x 10-3 s-1. At a given instant, the activity of a specimen of the nuclide is 70 mCi. After what interval of time interval will the activity decline to 10 mCi?
-880 s
-820 s
-690 s
-630 s
-750 s
Explanation / Answer
lot of question asked in a single go, skipping extra calculation
1.) 12,200
2.) the longest half-life in the series from uranium-238 to radon-222
3.) the electrical attraction between them and their electrons
4.) -630
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