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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.
How do you determine the half life of a radioactive substance that has changed through radioactive decay After 40 days the original substance left is is one sixteenth of the original amount?
the halflife is 10 days
After three half-lives what fraction of a radioactive sample remains?
1/8 of the original amount remains.
A sample of a radioactive substance decayed to 95 percent of its original amount after a year.what is the half life of the substance?
The half-life of a radioactive nuclide when 95% of it is left after one year is 13.5 years. AT = A0 2(-T/H) 0.95 = (1) 2(-1/H) ln2(0.95) = -1/H H = -1/ln2(0.95) H = 13.5
A substance is labeled as being radioactive The substance is?
Radioactive.
How much radioactive sample will be left at the end of two weeks?
That would depend on the initial amount of the substance, as well as on its half-life.
What do we call the time it takes for half of a radioactive sample to decay?
The time it takes for half of a sample to decay is called the "half-life" of the corresponding material.
What must be true for radioactive dating to be possible with a certain sample?
The sample must contain radioactive elements.
What is the difference between a non-radioactive substance and a radioactive substance?
Radioactive substances are unstable as a result of the extra neutrons present in the nuclei of the substance. Non-radioactive substances are stable.
How much of a 100-g sample of thorium-234 will be unchanged after 48.2 days?
25 gExplanation:Think about what a nuclear half-liferepresents, i.e. the time needed for an initial sample of a radioactive substance to be halved.
What happens to a radioactive material over time?
It disintegrates into its daughter nuclei that are much more stabler than the radioactive nuclei. If a sample of radioacictive material is left it will decay into another element over a period of time. Note that complete decay is not possible. A fraction of the original radioactive material will always remain in the sample.
How much of radioactive substance remains after 15 hours if it's half life is 5 hours?
The half-life of a radioactive substance is the time that it takes for half of the atoms to decay. With a half-life of 10 days, half has decayed in this time. After 20 days, a further 10 days/another half life, a further half of the remainder has decayed, so 1/4 of the original material remains, 1/4 of 15g is 3.75 grams. This is the amount of original radioactive substance remaining, but it’s daughter isotope ( what the decay has produced ) is also present, so the original sample mass is effectively constant, especially in a sealed container. Even in an unsealed container, and assuming alpha ( helium nucleii) emission, a drop in mass per radioactive atom of 4 Atomic Mass units, compared with the original atom of, say 200 amu is only 2% mass decrease, less for heavier decaying nucleii.
