Carbon-14 has a radioactive decay half-life of 5730 years. Which item would carbon-14 be most useful for datin?
The answer for the first question is B. a Native American fire pit. Carbon dating is used to date items that are not extremely old. Granite rocks are billions of years old and a different method is used to date them besides carbon-14. The other items are also very old, in the 100 of millions of years or billions of years. For the second one, most of the mass is in the middle, in the nuclear bulge, meaning the bulge (not buldge) in the middle (nucleus). A picture of a similar galaxy to ours showing a nuclear bulge: http://en.wikipedia.org/wiki/Bulge_(astr...
The half-life for the radioactive decay C-14?
The half-life for the radioactive decay of C-14 is 5730 years. How long will it take for 20% of the C-14 atoms in a sample of C-14 to decay? (in years) If a sample of C-14 initially contains 1.7 mmol of C-14, how many millimoles will be left after 2280 years?
Do all Carbon-14’s decay at the same time?
No. They break down randomly enough that a single atom cannot be timed. On the AVERAGE, half of a given sample will decay in 5730 (plus or minus 40) years into nitrogen-14. In each succeeding 5730 year period half of the remainder will decay. Carbon-14 is produced naturally in the upper layers of Earth's atmosphere following bombardment by cosmic rays. Life forms that take in carbon from the air have certain concentrations of carbon-14. When the life form dies, no more of this element is ingested and it begins to decay. The ratio of carbon-14 to nitrogen-14 in the formerly living tissue can be tested and used to give an approximate time of death. ----------- Additional: The smaller the sample, the less reliable are the results of the testing. A sample of four atoms would of course, be far too small to use. But there are trillions of Carbon-14 in most items tested. Even so, the limits for Carbon-14 dating is around 60,000 years. For items older than that, different elements are used for radiometric dating. .
Radioactive dating...?
All those radioactive dating works the same way. All elements have what is called a half-life. What this is, is a period (usually in years) where the amount of certain elements in the object becomes half of what the original values were. For example, carbon-14 has a half-life of 5730 years. All living things contain a certain amount of this carbon based element. If the object had half of what it should have, that means the object has been dead for 5730 years. If it had 1/4, then it means it was alive 10460 years, and so on. Potassium-argon has a half life of 1.26 billion years. Uranium 238 has a half life of 4.46 billion years. They are used to measure different range of dates.
1. The half-life of C-14 is 5700yrs. How many yrs. will it take for one gram of C-14 to decay to 0.25g.?
2. Element Y has two natural isotopes: Y-63 (62.940 amu) and Y-65 (64.928amu). Calculate the atomic mass of element Y given the abundance Y-63 is 69.17% 3.Of the common nuclear radiation, which ones have a charge of zero? 4. What period 5 element has chemical properties most like Silicon?