Almost all of naturally occurring uranium is ._92^238U with a half-life of 4.468xx10^9 yr. Most of the rest of natural uranium is ._92^235U with a half-life of 7.038xx10^8 yr.Today a sample contains 0.72% ._92^235U (a)What was this percentage 1.0 billion years ago ? (b)What percentage of the sample would be ._92^235U in 100 million years ?

Almost all of naturally occurring uranium is ._92^238U with a half-lif

1.	Almost all of naturally occurring uranium is ._92^238U with a half-life of 4.468xx10^9 yr. Most of the rest of natural uranium is ._92^235U with a half-life of 7.038xx10^8 yr.Today a sample contains 0.72% ._92^235U (a)What was this percentage 1.0 billion years ago ? (b)What percentage of the sample would be ._92^235U in 100 million years ?
Answer» ANSWER :(a)1.6% , (B)0.67 %

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