Radioactive Decay

Natural uranium consists of \({ }^{235} \mathrm{U}\) (percent abundance = 0.7200 %, \(\lambda=3.12 \times 10^{-17} / \mathrm{s}\)) and \({ }^{238} \mathrm{U}\)  (percent abundance = 99.27 %, \(\lambda=4.92 \times 10^{-18} / \mathrm{s}\)). What were the values for percent abundance of \({ }^{235} \mathrm{U}\) and \({ }^{238} \mathrm{U}\) when Earth formed \(4.5 \times 10^{9}\) years ago?

Text Transcription:

^235 U

lambda=3.12 times 10^17/s

^238 U

lambda=4.92 times 10^18/s

4.5 times 10^9