A radioactive isotope X with half-life of `693xx10^(9)` years decay to Y which is stable. A sample of rock from of the moon was found to contain both the elements X Y in the mole ratio `1:7` . What is the age of the rock ?
a) `2.079xx10^(12)` years
b) `1.94xx10^(10)` years
c) `1.33xx10^(9)` years
d) `10^(10)` years

Options

A. `2.079xx10^(12)` years
B. `1.94xx10^(10)` years
C. `1.33xx10^(9)` years
D. `10^(10)` years

Answer

A