half-life of carbon-14, 14C, is approximately 5,730 years. A bone fragment is estimated to have originally contained 5 milligrams of 14C. Write the exponential decay equation where A is the amount (in mg) of carbon-14 remaining in the bone fragment after t years. A =

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The radioactive isotope 212pb has a half-life of 10.64 h. A sample containing this isotope has an initial activity (t = 0) of 55.0 pCi. Calculate the number of nuclei that decay in tl time interval between t, = 7.0 h and t, = 15.0 h. nuclei

Xavier is at NASA analyzing Moon rocks. In one of the rocks from the lunar maria, he discovered 79 % of the original uranium-238 remains, while remaining amount of uranium-238 had decayed into lead. The half life of uranium-238 is 4.5 × 109 years. Assume the only decay product is lead. How old is the lunar maria rock in billions of years (109 years)?

This experiment will use a technique known as neutron activation analysis (NAA) to determine the half-lives of two unusual isotopes, 28 Al and 20F. The only stable isotopes of these elements are 27 Al and 19F. Trace amounts of 26 Al and 18F occur naturally, but the isotopes we will generate today are even more unstable and have no significant natural abundance. To produce these very unstable isotopes in measurable concentration, samples containing Al and F are placed next to a source of energetic neutrons. A number of neutron sources can be used; in this lab the samples are placed inside an operating nuclear reactor that emits energetic neutrons. This source has the advantage of a high neutron output that creates the desired isotopes rapidly and at higher concentrations, but it is only feasible for researchers that have access to nuclear reactors. At Oregon State University, the campus TRIGA reactor is set up for NAA experiments. SECTION 2 Based on the description from the last…

Radiocarbon dating techniques are used to determine that a very old piece of bone emits emits about 18 β-particles per sec. If a similarly-sized sample of modern bone emits about 144 β-particles per sec, and the half-life of 14C is 5730 years, approximately how old is this bone fragment (in years)?

If a tree dies and the trunk remains undisturbed for 1.635 × 10⁴ years, what percentage of the original ¹⁴C is still present? (The half-life of ¹⁴C is 5730 years.)

A sample of bone is subjected to radiocarbon dating. The current decay rate observed for its carbon-14 content is 11.2 disintegrations per minute per gram of carbon. What is the age (in years) of the bone? The half-life for carbon-14 is 5.73 x 103 yrs, and the decay rate for carbon-14 in living organisms is 14.3 disintegrations per minute per gram of carbon.

Archeologists continue to debate the arrival of the first humans in the Western Hemisphere. Radiocarbon dating of charcoal from a cave in Chile was used to establish the earliest date of human habitation in South America as 8700 years ago. This procedure involves comparing the 14C present in a sample of charcoal to the 14C present in a living tree of the same age. What fraction of the 14C initially present remained in the charcoal after 8700 years? The half-life of 14C is 5730 years. (Write the answer as a number with a decimal.)

* → esc → C 1 O NUCLEAR CHEMISTRY Understanding radioactive half life sample 1 6 A B Explanation A Announcemer X С A medical technician is working with the four samples of radionuclides listed in the table below. Initially, each sample contains 14.00 umol of the radionuclide. First, order the samples by decreasing initial radioactivity. Then calculate how long it will take for the amount of radionuclide in each sample to decrease to 1/32 of the initial amount. D Q ? N symbol 90 39 55 @ 27 133 54 203 82 Y 2 radionuclide Co https://www-awu.aleks.com/alekscgi/x/Isl.exe/10_u-IgNslkr7j8P3jH-IBMBkpcnaFu0F7UjsroJMKrbFHXPNvwILIE9DNBkbkvSm.... A Xe Pb 124 * Check S W X ALEKS-Chiso X alt # [tx half-life 64.0 hours 18. hours 5.0 days 2.0 days 3 * Q Search E D $ C 4 amathxl pearso X initial radioactivity (choose one): (choose one) v 14-jad (choose one) (choose one) ✓ R F 0 % V do 5 T G time for amount of radionuclide to decrease to 1/32 of initial amount 14- ^ Homework an X 6 B Y H hours hours…