Samarium has a half-life of approximately 106 billion years. If you found a sample of samarium from the beginning of Earth's history, approximately 4.6 billion years ago, which would be the best approximation of the amount of parent isotope left in the rock?

Nearly 100 percent

50 percent

25 percent

Less than 10 percent

Question

Samarium has a half-life of approximately 106 billion years. If you found a sample of samarium from the beginning of Earth's history, approximately 4.6 billion years ago, which would be the best approximation of the amount of parent isotope left in the rock?

Nearly 100 percent

50 percent

25 percent

Less than 10 percent

aaronq · Answer

106 = ln2/k

k= 6.539x10^-3

A=Aoe^(-kt)

A=100e^(-6.539x10^-3(4.6))

A= 97.036 %

anonymous · Answer

1st option.

thomaster · Answer

So.. after 106 billion years the sample contains 50% of isotopes
4.6 billion is only like 5% of that so its very logical that the answer is nearly 100%

goformit100 · Answer

Nearly 100 percent is the correct option