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After 2 half lives, 25% of the original radioactive sample remains unchanged. This is because half of the sample decays in each half life, so after 1 half life, 50% has decayed, and after 2 half lives, another 50% has decayed, leaving 25% unchanged.

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

After three half-lives, only 1/8 (or 12.5%) of the original radioactive sample remains. This is because each half-life reduces the amount of radioactive material by half, so after three half-lives, you would have (1/2) * (1/2) * (1/2) = 1/8 of the original sample remaining.


Is a radioactive sample has decayed until only one eighth of the original sample remains unchanged how many half lives have elapsed?

Three half lives have elapsed. This can be determined by calculating how many times the original sample size must be halved to get to one eighth: (1/2) * (1/2) * (1/2) = 1/8.


If Astatine-218 has a half-life of 1.6 s Suppose you have a 1.2-g sample of astatine-218 How much of the sample remains unchanged after 6.4 seconds Explain how you solved the problem?

After 1.6 seconds, 0.6 g astatine-218 remains unchanged. This amount is reduced by half to 0.3 g at 3.2 seconds. It is halved again at 4.8 seconds to 0.15 g, and halved once more to 0.075 g unchanged after a total of 6.4 seconds.


The half life of carbon 14 is 5730 years If a 1g sample of old carbon is one eighth as radioactive as 1g of a current sample then the age is about?

The ratio of radioactive carbon-14 in the old sample to the current sample is 1:8, suggesting 3 half-lives have passed. Since each half-life is 5730 years, the age of the old sample would be approximately 17190 years.


How does half life work in the context of radioactive decay?

In the context of radioactive decay, half-life is the time it takes for half of the radioactive atoms in a sample to decay. This means that after one half-life, half of the original radioactive atoms have decayed, and after two half-lives, three-quarters have decayed, and so on. The concept of half-life helps scientists understand the rate of decay of radioactive substances.

Related Questions

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

After 5 half-lives, 3.125% (or 1/2^5) of a radioactive sample remains. Each half-life reduces the sample by half, so after 5 half-lives, there is only a small fraction of the original sample remaining.


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

1/8 of the original amount remains.


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

After three half-lives, only 1/8 (or 12.5%) of the original radioactive sample remains. This is because each half-life reduces the amount of radioactive material by half, so after three half-lives, you would have (1/2) * (1/2) * (1/2) = 1/8 of the original sample remaining.


Is a radioactive sample has decayed until only one eighth of the original sample remains unchanged how many half lives have elapsed?

Three half lives have elapsed. This can be determined by calculating how many times the original sample size must be halved to get to one eighth: (1/2) * (1/2) * (1/2) = 1/8.


Which fraction of an original 20.00-gram sample of nitrogen-16 remains unchanged after 36.0 seconds?

Nitrogen-16 has a half-life of about 7.13 seconds. After 36.0 seconds, there would be 3 half-lives. Therefore, 1/2 * 1/2 * 1/2 = 1/8 of the original sample remains unchanged.


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 three half-lives?

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


What fraction of a sample remains after three half lives?

An eighth remains.


How many unchanges atoms would remain after 3 half lives if the initial sample had 600 unchanged atoms?

After 3 half-lives, half of the original sample would remain unchanged. After the 1st half-life: 300 unchanged atoms. After the 2nd half-life: 150 unchanged atoms. After the 3rd half-life: 75 unchanged atoms would remain.


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.


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

Approx 1/8 will remain.