A threory of nuclear astrophysics is that all the heavy elements like uranium are formed in supernova explosions of massive stars, which immediately release the elements into space. If we assume that at the time of the explosion there were equal amounts of 235U and 238U, how long ago were the elements that formed our Earth released, given that the present 235U/238U ratio is 0.007? (The half-lives of 235U and 238U are 0.70 x 10^9 yr and 4.47 x 10^9 yr, respectively)
If N0 is the initial quantity, after a time t years, the amount of quantity of radioactive material left N = N0*exp(-lambda*t), where lambda = 0.693/half life.
<br><br>Given that N0 was same initially for ...
...Radioactive Decay. ... with some initial amount N0 , then N (5730) will represent half of the initial 1 amount, because half of the initial amount decays after 5730 ...
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Rates of Radioactive Decay. A one- milligram sample of Cu-64 (nuclear mass =63.92 amu) has an activity of 3.82*10^3 Ci. 1a) How many atoms are in the sample? ...
... Count the number of alpha decays. ... 9 years, after that time (N / 2) U-238 atoms would have decayed. ... that all of the helium was formed by radioactive decay of U ...
Nuclear Chemistry : Radioactive Decay. Question 1 A radioisotope decays to give an alpha particle and Pb-208. What was the original element? Se Bi Po Hg Rn. ...
... constant, a characteristic of the isotope that is decaying. Plugging in the values: ... The expert determines the rate of radioactive decay. Posting ID: 60437:
