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If 20 of a radioactive substance disappears in 70 days what is its half life?
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∙ 14y ago
we need to know the units of 20. Is it grams, kilograms, %...
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∙ 14y ago
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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
How many days in 9 and a half days?
9 and a half days = 9 and a half days , 228 hours, 13680 minutes, 820800 seconds.
Half an hour is how many days?
no days just half an hour
How many days in 4 in a half days?
In 4 and a half days, there would be 4 whole days and a half of the next day, 12 out of the 24 hours perhaps !
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
If 10 percent of a radioactive substance disintegrates in 4 days what is it's half-life?
20 days
What is definition of half life?
The time required for half of the atoms in a radioactive substance to disintegrate.
A radioactive substance has has life of 5 days initial mass of 12kg how much the original isotope will remain after 10 days?
a radio active substance has half life of 5 days initial mass of 12kg.how much the original isotope will remain after 10 days?
To use radioactive dating for a substance you must know the substances?
Half-life
A particle element has a half-life of 27 days after 54 days have elapsed how much of the radioactive material is left is called?
54 days is 2x27. After one cycle of a half life (27 days), one-half of the substance would be left. After a second cycle of a half life (27 more days, for a total of 54), one-half of one-half is left, or one-fourth.
30 gram of a radioactive substance that has a half-life of 2 days after 2 days how much will be left?
With radioactive decay, predicting when any individual atom will decay is nearly impossible. However, when a lot a particles are present, then it is possible to get a general idea of how much will decay in a certain period of time. The half-life is this measurement, and it is the time that it takes for one halfof the substance to decay. Hence half-life or how long it takes for half to "die".For any size sample of a substance, the half-life is how long it takes for half to be left, so for a substance with a half-life of 2 days, half of the substance will decay in two days. Therefore your answer is simply half of 30g which is 15g.Additional reading: http://simple.wikipedia.org/wiki/Radioactive_decay
What is the half life of a radioactive substance that has changed through radioactive decay after 40 days the original substance left is one sixteenth of the original amount?
Let us use the expression = time duration = number of half lives x half life Given 40 = 4 x half life So half life = 10 days. Remaining = 1/16 = (1/2)4. So 4 half live have gone. If the number of half lives is n then (1/2)n would remain.
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 pure radioactive substance has a half-life of 3 hours. How long would it take a mass of 12g of that substance to decay to 3g?
Twice the half-life.
What does a half life of a radioactive substance indicate?
It indicates how long it takes for the material to decay.
What does the half life of a radioactive substance indicate?
It indicates how long it takes for the material to decay.
