Monazite sample contains 9% `ThO""_(2)` and 0.35% `U""_(3)O""_(8).Pb""^(208)` and `Pb""^(206)` are the stable and products in the radioactive decay series of `Th""^(232)` and `U""^(238)` respectively. All the lead in mozaite is of radiogenic origin.
The isotopic ratio of `Pb""^(208)/Th""^(232)` was found to be 0.104. The half lives of Th and U are `1.41xx10""^(16)` years and `4.47xx10""^(9)` years respectively.
Estimated isotopic ratio of `Pb""^(206)//U""^(238)` in the monazite sample will be
A. 0.166
B. 0.266
C. 0.366
D. 0.466
