The present day abundances of the isotopes `U^(238)` and `U^(235)` are in the ratio of 128: 1. They have half lives of `4.5times10^(9)` years and `7times10^(8)` years respectively.If age of earth in `(49X)/(76)times10^(7)` years, then calculate X (Assume equal amount of each isotope existed at the time of formation of the earth)

A sample of Uranium is a mixture of two isotopes ._(92)^(234)U and ._(92)^(238)U present in the ratio 10% and 90% by weight. The half lives of these isotopes are 2.5 xx10^(5) years and 4.5 xx10^(5) years respectively. Calculate the contribution to activity in percentage of each isotope in this sample.

Calculate the specific activities of Na^(24) & U^(235) nuclides whose half lives are 15 hours and 7.1xx10^(8) years respectively.

Uranium ores on the earth at the present time typically have a composition consisting of 99.3% of the isotope _92U^238 and 0.7% of the isotope _92U^235 . The half-lives of these isotopes are 4.47xx10^9yr and 7.04xx10^8yr , respectively. If these isotopes were equally abundant when the earth was formed, estimate the age of the earth.

A sample of uranium is a mixture of three isotopes ._(92)U^(234), ._(92)U^(235) and ._(92)U^(238) present in the ratio 0.006%, 0.71% and 99.284% respectively. The half lives of then isotopes are 2.5xx10^(5) years, 7.1xx10^(8) years and 4.5xx10^(9) years respectively. The contribution to activity (in % ) of each isotope in the sample respectively

A sample of uranium mineral was found to contain Pb^(208) and U^(238) in the ratio of 0.008 : 1. Estimate the age of the mineral (half life of U^(238) is 4.51 xx 10^(9) years).

In the chemical analysis of a rock the mass ratio of two radioactive isotopes is found to be 100:1 . The mean lives of the two isotopes are 4xx10^9 years and 2xx10^9 years, respectively. If it is assumed that at the time of formation the atoms of both the isotopes were in equal propotional, calculate the age of the rock. Ratio of the atomic weights of the two isotopes is 1.02:1 .