121 days
There are 31 days in March. March in 2015 only has four full weeks of 7 days, with 3 days remaining.
The half-life of a radioactive substance is the time that it takes for half of the atoms to decay. With a half-life of 10 days, half has decayed in this time. After 20 days, a further 10 days/another half life, a further half of the remainder has decayed, so 1/4 of the original material remains, 1/4 of 15g is 3.75 grams. This is the amount of original radioactive substance remaining, but it’s daughter isotope ( what the decay has produced ) is also present, so the original sample mass is effectively constant, especially in a sealed container. Even in an unsealed container, and assuming alpha ( helium nucleii) emission, a drop in mass per radioactive atom of 4 Atomic Mass units, compared with the original atom of, say 200 amu is only 2% mass decrease, less for heavier decaying nucleii.
To determine how many days are left until the year 3000 from 2023, we first calculate the number of years remaining, which is 977 years. Multiplying 977 by 365 gives approximately 356,205 days. However, accounting for leap years, the total would be a bit higher, roughly 356,207 days. Thus, there are about 356,207 days until the year 3000.
4 weeks and 2 days. 30 divided by 7 equals 4 with 2 remaining.
To find the remaining mass of a radioactive isotope after a certain time, you can use the radioactive decay formula: [M_{\text{final}} = M_{\text{initial}} \times \left( \frac{1}{2} \right)^{\frac{t}{t_{1/2}}}] Given that the half-life of (^{222}\text{Rn}) is 3.8 days, and the initial mass is 160 milligrams, you can substitute these values into the formula to find the final mass.
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.
The half-life on 222Rn86 is 3.8235 days. A sample of this isotope will decay to 0.8533 of its original mass after 21 hours. AT = A0 2(-T/H) AT = (1) 2(-21/(24*3.8235)) AT = 0.8533
After 32 days, approximately 5 milligrams of the 80-milligram sample of Iodine-131 would be left. Iodine-131 has a half-life of about 8 days, so after each 8-day period, half of the remaining sample will decay.
After 133.5 days, there will be 0.125 mg of the 2 mg sample of iron-59 remaining. This can be calculated by taking into account each half-life period (44.5 days) and calculating the remaining amount after 3 half-lives (133.5 days).
After 48,2 days the amount of Th-234 will be 25 g.
At 2.7 days, half of the 800 atoms (400 atoms) would have decayed. At 8.1 days, three half-lives have passed, so only ( \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = \frac{1}{8} ) of the original sample remains. Therefore, there are 100 atoms of Au-198 remaining in the sample after 8.1 days.
Let's step through the half-life of radon to see how it works. Radon-222 starts at full strength. In four days (its half-life), it is at half strength. In four more days, it is again at half strength (of the half strength) for a total of 1/4 strength. In four more days, it is again half the strength (of the 1/4 strength) for a total of 1/8 strength. In four more days, it is another half life weaker, for a total of 1/16 strength. In 16 days, this isotope of radon has just 1/16th the original radiation.
18 grams are one fourth of the original sample mass of 72 grams. Accordingly, the half life is 6.2/4 = 1.55 days.
If a radioactive sample contains 1.25g of an isotope with a half-life of 4.0 days, then 0.625g (1/2) of the isotope will remain after 4.0 days, 0.3125g (1/4) after 8.0 days, 0.15625g (1/8) after 12.0 days, etc. AT = A0 2(-T/H)
Thorium-234 has a half-life of 24.1 days. How much of a 100-g sample of thorium-234 will be unchanged after 48.2 days?
The mass can be determined with the formula m=800(.5)^(t/5)