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The isotope of U^(238) and U^(235) occur...

The isotope of `U^(238) and U^(235)` occur in nature in the ratio `140:1`. Assuming that at the time of earth's formation, they were present in equal ratio, make an estimate of the age of earth. The half lives of `U^(238)` and `U^(235)` are `4.5xx10^9` years and `7.13xx10^8` years respectively. Given `log_(10)140=2.1461 and log_(10)2=0.3010.`

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