Plutonium-239 has a half-life of about 24,100 years, meaning it takes that long for half of a sample to decay. In 43 years, which is much shorter than the half-life, only a tiny fraction of the plutonium would decay. Therefore, after 43 years, approximately 99.83 grams of the original 100-gram sample would remain.
The answer depends on 3240 WHAT: seconds, days, years?
Carbon-14 has a half-life of about 5,730 years. If a wood sample contains 12.5% of its original carbon-14, it has undergone four half-lives (since 100% → 50% → 25% → 12.5%). Therefore, the true age estimate of the sample is approximately 22,920 years (4 half-lives x 5,730 years per half-life).
5730 years (approx).
After 28 years your sample halves, ie becomes 38 mg. In another 28 years it will have halved again to 19 mg, so your answer is 56 yearsIt may not seem important, but you should remember that your sample is not evaporating. The actual 76 mg sample will still have almost all of its mass after 56 years. But by that time only 19 mg of it will be strontium-90. The rest of the sample will still be there, but it will have become Zirconium-90 which is stable.And thank your teacher for giving you an easy number to work with. The actual half-life is closer to 28.8 years.
40 years
The half life of the isotope 239Pu (the most known plutonium isotope) is 24,200 years; 43 years is practically nothing in comparison is 24,200 years so you would still have 100 grams.
5g would remain
The half life of plutonium-239 is 2,41.10e+4 years.
I suppose that you think to the radioactive isotope Cs-17; After 4 years remain 9,122 g.
Approximately 400 grams of the potassium-40 sample will remain after 3.91 years, as potassium-40 has a half-life of around 1.25 billion years. This means that half of the initial sample would have decayed by that time.
The half-life of 27Co60 is about 5.27 years. 15.8 years is 3 half-lives, so 0.53 or 0.125 of the original sample of 16 g will remain, that being 2 g.
2 1/2 g
2 1/2 g
2 1/2 g
After 6 years, approximately 5 grams of cesium-137 would remain from a 10 g sample due to its half-life of around 30 years. This decay is exponential, with about half of the original sample decaying every 30 years.
The half-life of plutonium-241 is about 14 years. This means that it takes approximately 14 years for half of a sample of plutonium-241 to decay into another element.
You must know the half life of Caesium to calculate this.