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Sahay Sir > Question Answers > Cengage JEE Mains Physics by B.M Sharma > Chapter 30 - Nuclear Physics > 238U decays with a half-life of 4.5×10^9 years, the decay series eventually ending at .206Pb, which is stable. A rock sample analysis shows that the ratio of the number of atoms of .206Pb to .238U is 0.0058. Assuming that all the .206Pb is produced by the decay of .238U and that all other half-lives on the chain are negligible, the age of the rock sample is (In1.0058 = 5.78 × 10^−3).

238U decays with a half-life of 4.5×10^9 years, the decay series eventually ending at .206Pb, which is stable. A rock sample analysis shows that the ratio of the number of atoms of .206Pb to .238U is 0.0058. Assuming that all the .206Pb is produced by the decay of .238U and that all other half-lives on the chain are negligible, the age of the rock sample is (In1.0058 = 5.78 × 10^−3).

238U decays with a half-life of 4.5×10^9 years the decay series eventually ending at .206Pb The percentage of quantity of a radioactive material that remains after 5 half-lives will be .