Answer: Its B. There will be 0.031 kg left after 151 years,
Explanation: Im doing my assessment right now.
The half-life of Cs-137 is 30.2 years. If the initial mass of the sample is 1.00 kg, the mass remain after 151 years is 0.031 Kg.
Caesium-137, or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes.
Cs-137 is used in medical radiation therapy devices for treating cancer.
The half-life is the amount of time it takes for a given sample to lose half of the original amount or the time for radioactive substance to decay. The half-life of Cs-137 is 30.2 years.
Decay constant of radioactive substance is its probability of decay per unit time.
In this case,
Mass of sample is 1 Kg
Half-life of Cs-137 is 30.2 years
The elapsed time is 30.2 years.
This means, one half-life is elapsed, the half of sample will decay in 30.2 years. Therefore, the half of the original substance will remain in 30.2 years which is 0.500 Kg. After another 30.2 years, it will be 0.250 Kg. And after 151 years, it will be 0.031 Kg.
To learn more about Cs-137 here
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