A sample of rock from moon contains equal number of atoms of uranium and lead `(t""_(1//2)for U=4.5xx10""^(9)`year). The age of the rock would be a)`4.5xx10""^(9)` year b)`9xx10""^(9)` year c)`13.5xx10""^(9)` year d)`2.25xx10""^(9)` year

Options

A. `9.0 xx 10^(9)` years
B. `4.5 xx 10^(9)` years
C. `13.5 xx 10^(9)` years
D. `2.25 xx 10^(9)`years

Answer

B

Explanation

`N = (N_(0))/(2^(n)), " use " t = (2.303 xx t_(1//2))/(0.693) " log" (N_(0))/(N)`