Respuesta :
Since the half-life is 4.5 billion years, two half-lives would have elapsed after 9 billion years.
If you start with 400 g, half decays during the first half-life, leaving 200 g.
During the second half-life, half of the 200 g decays, leaving 100 g.
If you start with 400 g, half decays during the first half-life, leaving 200 g.
During the second half-life, half of the 200 g decays, leaving 100 g.
The half-life period of uranium-238 is about 4.5 billion years.
Two half-life period of Uranium-238 would have completed in 9 billion years.
Original sample of Uranium-238 had a mass of 400g
Half of the uranium-238 would have disintegrated in the first half-life period
i.e., leaving 200g behind.
During the second half-life period, the 200g of uranium-238 would have disintegrated to 100g leaving 100g of sample behind.
Hence,100g of Uranium-238 would be left after 9 billion years.
What is Half-life?
Half-life is "the time required for half of the atoms of a radioactive substance to become disintegrated".
What is Uranium-238?
Uranium-238 is a naturally occuring isotope of uranium.
To learn more about Half-life here
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