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.
The half-life of cesium-137 is approximately 30.1 years, not 2 years. After one half-life, 5 G of the original 10 G sample would remain. After two half-lives (about 60.2 years), 2.5 G would remain, and so on. If you meant a hypothetical isotope with a 2-year half-life, after 2 years, 5 G would remain, and after 4 years, 2.5 G would remain.
5g would remain
I suppose that you think to the radioactive isotope Cs-17; After 4 years remain 9,122 g.
This time is 17 190 years.
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.
The half-life of cesium-137 is approximately 30.1 years, not 2 years. After one half-life, 5 G of the original 10 G sample would remain. After two half-lives (about 60.2 years), 2.5 G would remain, and so on. If you meant a hypothetical isotope with a 2-year half-life, after 2 years, 5 G would remain, and after 4 years, 2.5 G would remain.
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.
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.
10 grams... If the half-life is 100 years, that means after 100 years, half the original mass remains. After another 100 years, the mass is halved again. 40/2=20... 20/2=10.
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.
5g would remain
The answer depends on 3240 WHAT: seconds, days, years?
I suppose that you think to the radioactive isotope Cs-17; After 4 years remain 9,122 g.
This time is 17 190 years.
After 10740 years, half of the sample would have decayed, so there would be 200 atoms left. If the original sample had 400 atoms, then there would be 200 atoms left in the sample after 10740 years.
After 50 years, 1500 g of actinium-227 will have undergone approximately 2.3 half-lives (50 years / 21.772 years per half-life). This means that approximately 25% (50% decayed after 1 half-life, and 50% of the remaining amount decays after the second half-life) of the original sample will remain radioactive, so there will be around 375 g of actinium-227 remaining.