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Not sure what you mean by "had-lives". After 3 half lives, approx 1/8 would remain.

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Solon Zboncak

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1y ago
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13y ago

1st half life: 0.5 = 1/2

2nd half life: 0.5*0.5 = 0.25 = 1/4

3rd half life: 0.5*0.5*0.5 = 0.125 = 1/8

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8y ago

You need to calculate (1/2) to the power 3.

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8y ago

0.5 x 0.5 x 0.5, or 0.125 (one eighth).

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6y ago

The remaining is 1/8.

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Q: What fraction of a radioactive sample remains after three half lives?
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How much of a 400-gram sample of K40 is left after 2 half-lives?

After the first half-life, you will have one half of the starting amount. After a second half-life period, you'll be down to one quarter. Of the part that radioactively decays, about 11% of it will decay to 40Ar, and the remainder to 40Ca. Of your total sample of ordinary potassium, only 0.012% will be 40K. The half-life of 40K is about 1.3x109 years.


What are monoisotopic elements?

Mono isotopic elements are stable isotope of an element.From 80 isotopic elements there are 26 radioactive elements discovered up till now.These mono isotopic may or may not be radioactive if they are radioactive they have halve lives.


Is oxygen stable or radioactive?

Oxygen, under normal conditions, is non-radioactive. But there are traces of radioactive isotopes present which makes the oxygen slightly radioactive. Additionally, these isotopes have long half-lives, so the radiation given off will not be a lot within a period of time.


What fraction of chlorine 36 remains undecayed after 2000000 years?

the half-life of chlorine 36 is 400,000 years. 200,000 years is 1/2 of a half life. in general, the formula to calculate the fraction of remaining amount is 1/2^n, where n represents the number of half-lives that have passed. in this case, n=1/2, or 0.5, therefore the remaining fraction is 1/2^0.5. Use your calculator and you will find that this is 0.707, or about 71% of the original amount. hope this helps


How many lives do hurricanes take?

The most amount of lives taken by hurricanes is 300,000.

Related questions

Why After three half-lives what fraction of a radioactive sample remains?

The fraction that remains is 1/8.


After three half-lives what fraction of a radioactive sample remains?

1/8 of the original amount remains.


What fraction of a sample remains after three half lives?

An eighth remains.


What percentage of a radioactive sample remains after 5 half-lives?

3.1 %


What fraction of a radioactive sample remains after three half-lives?

Not sure what you mean by "had-lives". After 3 half lives, approx 1/8 would remain.


After three half-lives what fraction of a radioactive sample will remain?

Approx 1/8 will remain.


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.


What fraction of a radioactive sample remains after one half-life?

Half of the original sample of a radio isotope remains after a half-life period. After two half-life periods, one-fourth of the radio isotope remains.


How can half lives be shortened?

Half life of an element can't be changed.. It is a characteristic of a radioactive element which is independent of chemical and physical conditions.. Half life is that time in which half of radioactive sample( i.e., a radioactive element) decomposes. So no matter what amount you take half life of an element remains same.


Approximately what fraction of an original Co-60 sample remains after 21 years?

Half-life is 5.27 years; 21 / 5.27 = 3.99, or almos 4 half-lives; (1/2)4 = 1/16.


If the isotope have short half lives is that mean that the isotope is in a stable condition?

No. Only radioactive elements have half-lives, the half-life is the time that it will take for half of the atoms in a sample of a radioactive isotope to decay into another element or isotope. This is a constant property of the isotope and does not depend on the sample size. Stable isotopes never decay.


What fraction of a radioactive nuclei remain after p half lives?

The remainder is 2-p or 0.5p of the original amount.