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If a radioactive sample has decayed until only one eighth of the original sample remains unchanged how many half-lives have elapsed?
Wiki User
∙ 6y ago
This depends on the type of material. Uranium-238's half-life is 4,438,000,000 years. But the half-life of a material such as Radon-218 is only 35 ms. There is a great range of half-lives for a wide variety of isotopes, so it is impossible to generalize. If you're asking what a half-life is, it is the amount of time it takes for half of any quantity of a radioactive isotope to decay. So if you had a 10g pile of Uranium-238, after 4,438,000,000 years, only 5g of it would still be Uranium-238. The other half would've decayed.
Wiki User
∙ 11y ago
Wiki User
∙ 16y agoEight years. That is what half life means. Half the material will be gone after the half life is reached. Three quarters will be gone after 16 years and 7/8ths gone after 24 years.
Wiki User
∙ 15y ago1/8 of its original mass as "that" material.
Wiki User
∙ 12y agoIf a radionuclide has a half-life of two years, then there will be 0.25 of it left after four years.
Wiki User
∙ 12y agoIf 1/8th of a sample remains after 12 years then the half-life is 4 years. The half-life sequence is 1/2, then 1/4, then 1/8, etc.
Wiki User
∙ 14y ago3 half-lives. 1/2, 1/4, then 1/8.
Wiki User
∙ 14y ago30 days
Wiki User
∙ 13y ago2 grams.
Wiki User
∙ 6y ago3
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Where does decayed matter come from?
Dead Animals and plants?
Which soil is made from ancient decayed forests?
it breaks down
-blank- are made up of decayed and decomposed plant and animal matter?
crude oil
What is empty space in rock showing the exact shape of the organism that was buried and decayed there?
Mold
Why are you likely to find dark brown soil in a forest?
you are likely because it is organic matter formed from decayed plant and animal remain ,and is called humus.
Why is radioactive waste considered safe after 10 half lives?
I would consider it safe after 5 half-lives. by 5 it has decayed to 3% of original level, by 10 it has decayed to 0.1% of original level.
What is the stable isotope that is formed by the breakdown of a radioactive isotope?
That's called a daughter isotope, or a daughter product. (The original isotope that decayed is the parent isotope.)
How much of a radioactive substance remains after 10 hours if its half life is 5 hours?
Since half of the atoms of the original substance will have decayed after 5 hours, half of what is left will have decayed after the next five hours. The answer is 0.25 or one fourth of the original atoms will remain.
How is radioactive decay used to determine the absolute age a rocks?
The basic idea is to measure the amount of the radioactive isotope, and of one or more of its decay products. The older the rock, the larger the percentage of the original isotope that decayed - so the ratio between the original isotope and the decay product changes over time.
What is the destiny of neptunium?
Being radioactive neptunium is decayed down to a stable isotope.
Which gaseous radioactive waste product that is released into the atmosphere after it has decayed to a safe radiation level?
radon-222
What is the difference between a simulation and actual radioactive decay?
Similarity: Both show that the radioactive atoms decrease and decayed atoms increase Difference: an actual decay is longer.
How does a sample of radioactive waste decay to a nonhazardous level?
All radioactive material has a characteristic half-life. This is a period during which half the matter from the original mass will have decayed into a daughter element. Either the daughter element is non-radioactive and therefore non-hazardous or it is radioactive and has its own half-life. The total radioactivity thus reduces over time and at some stage is deemed to reach a non-hazardous level.
Why will the amount of a radioactive substance never reach zero amount present?
The total amount of radioactive substance will never reach zero because it decays in half-lives. For C-14 is 5730 years, this means that after 5730 years one half of the original material will have decayed. After another 5730 years the remaining radioactive material (1/2 the original) will have decayed by 1/2 once again. -An infinite crowd of mathematicians enters a bar. The first one orders a pint, the second one a half pint, the third one a quarter pint... "I understand", says the bartender - and pours two pints.
After two half-lives, how much of the original material has decayed?
75%
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.
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
