If it was fully radio-active at the beginning, after 5 hrs it is 50%, at 10 hrs it is 25%, at 15 hrs it is 12.5%, and at 20 hrs it is only 6.25% as radioactive as it was at the beginning.
halflife
After two minutes, half of the radioactive atoms will remain. After another two minutes, half of the remaining atoms will decay, leaving 1/4 of the original amount. Therefore, 1/4 of the radioactive atoms will be left after four minutes.
The question does not make sense. The half-life of bromine-74 is, in fact, 25.4 minutes. In 25 minutes, that 4mg sample will decay to 2mg. In 25 more minutes it will decay to 1mg. In 25 more minutes it will be 0.5mg. And so on and so forth. If you meant to ask how much will remain after a given period of time, please restate the question.
The length of time required for half of a sample of radioactive material to decay
I suppose that you think to the radioactive isotope Cs-17; After 4 years remain 9,122 g.
halflife
Approx 1/8 will remain.
After two minutes, half of the radioactive atoms will remain. After another two minutes, half of the remaining atoms will decay, leaving 1/4 of the original amount. Therefore, 1/4 of the radioactive atoms will be left after four minutes.
The question does not make sense. The half-life of bromine-74 is, in fact, 25.4 minutes. In 25 minutes, that 4mg sample will decay to 2mg. In 25 more minutes it will decay to 1mg. In 25 more minutes it will be 0.5mg. And so on and so forth. If you meant to ask how much will remain after a given period of time, please restate the question.
No, the size of a radioactive sample does not affect its half-life. The half-life is a characteristic property of a radioactive isotope, defined as the time it takes for half of the radioactive atoms in a sample to decay. This property is intrinsic to the isotope itself and remains constant regardless of the amount of material present. Thus, whether you have a small or large sample, the half-life will remain the same.
100 grams
The length of time required for half of a sample of radioactive material to decay
I suppose that you think to the radioactive isotope Cs-17; After 4 years remain 9,122 g.
100 grams
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.
If a sample of radioactive material has a half-life of one week the original sample will have 50 percent of the original left at the end of the second week. The third week would be 25 percent of the sample. The fourth week would be 12.5 percent of the original sample.
If the substance has a half-life of 10 years, there would be 10 half-lives in a 100-year span. Each half-life reduces the amount by half, so after 100 years, 1/2^10 = 1/1024 grams of the sample would remain.