Question

A rock originally has 2200 atoms of 235U and no 207Pb. It now has 800 atoms of 235U. Assuming the only chemical process is the radioactive decay of uranium to lead, what is the age of the rock

Answer 1

`Age=1040.55 million\ years`

Step-by-step explanation:

From the question we are told that:

Initial Rock atoms
`a_1=2200atoms of 235^U`

Final Rock atom
`a_2=800 of  235^U`

Age of half life 713 million years

Generally the equation for Age is mathematically given by

`(1)/(2^n)=(800)/(2200)`

`(1)/(2^n)=(1)/(2.750)`

`n=1.46`

Therefore

`Age=713*1.46`

`Age=1040.55 million\ years`