b A sample of moon rock is found to contain 26 potassium40 a

(b) A sample of moon rock is found to contain 26% potassium-40 and 74% argon by mass. Calculate the age of the rock.

Solution

ln(Ao/A)=kt

k=ln2/T

where T is the half life.so,

ln(100/26)=kn(2) * (t/(1.2*10^9))

or t=2.33*10^9 years