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After one half-life, one half, 0.5, of a radionuclide will remain.
After a second half-life, one half of the half, 0.25, will remain, and then after a third, 0.125, and so on.
The equation for half-life is ...
AT = A0 2(-T/H)
... where A0 is the original activity, AT is the activity after some time T, and H is the half-life in units of T.
Keep in mind that the specific half-life only applies to the original nuclide, and that daughter products may well form and have their own half-lives. Also, half-life is relatively constant for each nuclide, unless some chemical situation is present, such as a fully ionized (electron stripped) nuclide, which can inhibit electron initiated decay, such as beta+ and internal conversion.
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A radioactive sample has a half-life of 5.0 min What fraction of the sample is left after 20 min?
After 20 minutes, there have been 4 half-lives (20 min / 5 min per half-life). Each half-life reduces the sample by half, so the fraction of the sample left after 20 minutes is (1/2)^4, which is 1/16. Therefore, 1/16 of the original sample is left after 20 minutes.
If gallium-68 has a half-life of 68.3 minutes how much of a 10.0-mg sample is left after one half-life?
5 mgs If you found this helpful please click trust below
A particular element has a half life of 27 daysafter 54 days how much of the radioactive material is left?
The half life is the time it takes for half the atoms in a given sample to decompose. Knowing this then after 27 days there is half the amount left. After 54 days then there is half that half left so that's a quarter.
What fraction of a radioactive sample decays after three half lives?
If I take a radioactive sample of 400 moles of an unknown substance and let it decay to the point of three half-lives I would have 50 moles left of the sample. 1/2 of what is left will decay in the next half-life. At the end of that half-life I will have 25 moles left of the unknown substance or 4/25.
If the half-life of a radionuclide is 1 month is a sample of it completely decayed after 2 months?
No, it is not. If a radionuclide has a half-life of 1 month, half is gone after 1 month. Half of the half that is left will be gone after 2 months, and that will leave 1/4th of the original amount left after the second month.
How much of the original sample will be left at the end of the second day if a sample of radioactive isotope has a half life of 1 day?
Hi, Each half-life means the mass of the sample has decreased by 1/2 its mass. Thus; After 1 half-life, 1/2 the sample has decayed. After 2 half-lives 3/4 of the sample has decayed. Hope this helps.
A sample of radioactive isotope has a halflife of 1 day how much of the original sample will be left at the end of the fourth day?
If a sample of radioactive material has a half-life of one week the original sample will have 50 percent of the original left at the end of the second week. The third week would be 25 percent of the sample. The fourth week would be 12.5 percent of the original sample.
A radioactive sample has a half-life of 5.0 min What fraction of the sample is left after 20 min?
After 20 minutes, there have been 4 half-lives (20 min / 5 min per half-life). Each half-life reduces the sample by half, so the fraction of the sample left after 20 minutes is (1/2)^4, which is 1/16. Therefore, 1/16 of the original sample is left after 20 minutes.
How much cesium is left after 4 half-lives?
1/16 of the original sample of any unstable element remains after 4 half lives.
If gallium-68 has a half-life of 68.3 minutes how much of a 10.0-mg sample is left after one half-life?
5 mgs If you found this helpful please click trust below
A particular element has a half life of 27 daysafter 54 days how much of the radioactive material is left?
The half life is the time it takes for half the atoms in a given sample to decompose. Knowing this then after 27 days there is half the amount left. After 54 days then there is half that half left so that's a quarter.
What fraction of a radioactive sample decays after three half lives?
If I take a radioactive sample of 400 moles of an unknown substance and let it decay to the point of three half-lives I would have 50 moles left of the sample. 1/2 of what is left will decay in the next half-life. At the end of that half-life I will have 25 moles left of the unknown substance or 4/25.
If a sample is 10740 years old and has 400 atoms how many atoms are there after the organisms died?
After 10740 years, half of the sample would have decayed, so there would be 200 atoms left. If the original sample had 400 atoms, then there would be 200 atoms left in the sample after 10740 years.
If the half-life of a radionuclide is 1 month is a sample of it completely decayed after 2 months?
No, it is not. If a radionuclide has a half-life of 1 month, half is gone after 1 month. Half of the half that is left will be gone after 2 months, and that will leave 1/4th of the original amount left after the second month.
What is the percentage of radioactive nuclei left after 3 half lives have passed?
12.5%
The half-life of an isotope is the time required for half the nuclei in a sample to?
Half-life is the length of time required for half the atoms in a radioactive sample to decay to some other type of atom. It is a logarithmic process, i.e. in one half-life, there is half the sample left, in two half-lives there is one quarter the sample left, in three half-lives there is one eight left, etc. The equation is... AT = A0 2 (-T/H) ... where A is activity, T is time, and H is half-life.
How much of an 8 gram sample is left after 3 half lives?
2.66666666666667 grams
