###### Asked in Chemistry

Chemistry

# If there is a radiation that has a half life of 10 days and you have it for 110 days what will be the fraction of radiation left?

## Answer

###### Wiki User

###### July 12, 2009 5:32AM

110 days would be 11 half-life periods if the half-life is 10 days. That means at the end, 1/2 x 1/2 x 1/2 ... (11 times) would be left: 2-11, or about one part in two thousand.

## Related Questions

###### Asked in Chemistry, Nuclear Physics

### Radioactive material with a half life of 5 days and you have it for 50 days than what fraction of radiation will be left?

After 5 days, you have half left.
After 10 days, that's half of the half again = a quarter.
After 15 days, that's half of a quarter = an eighth.
After 20 days, that's half an eighth = one sixteenth.
After 25 days = 1/32
After 30 days = 1/64
After 35 days = 1/128
After 40 days = 1/256
After 45 days = 1/512
After 50 days = 1/1024th of the initial radiation.

###### Asked in Medication and Drugs

### If the half life of iodine 131 is 8 days how much of the 5 gram sample is left after 32 days have passed?

You start with 5 grams- every 8 days, half of what is there goes
away. At 8 days. there will be 2.5 grams. At 16 days, half of THAT
is gone- now down to 1.25 grams. At 24 days, half of THAT is gone,
leaving 0.625 grams. At 32 days, you have half of 0.625 grams. so
divide .625 by two and you get .3125.

###### Asked in Nuclear Physics

### 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
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moles left of the unknown substance or 4/25.

###### Asked in Physics, Chemistry, Nuclear Physics

### 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 half
of 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

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### How long does Valiums stay in your system?

Valium is just about the slowest tranquilizer in leaving the
body. Its half-life is around 200 hours. That means that after 200
hours, half of it will have left your system. After another 200
hours, half of what was left will have left your system.
After another 200 hours, half of what was left will have left
your system.
200 hours is somewhat less than 10 days. Say 8 or 9 days. Half
of that is 4 or 4-1/2 days more. So after 12 to 13-1/2 days, only
1/4 of the original amount is left in your system. It may take
months for the drug to drop below a detectable level.
Valium is also fat-soluble. That means that any left over can
and will be stored in your fat cells. It may not come out normally
right away, but will wait until the next time that you exercise
heavily, then it will be back in your bloodstream again.

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