`._(19)^(49)K` isotope of potassium has a half-life of `1.4 xx10^(9)` yr and decays to form s
Channel: Doubtnut
Date: 26/07/2020

`._(19)^(49)K` isotope of potassium has a half-life of `1.4 xx10^(9)` yr and decays to form stable argon, `._(18)^(40)Ar`. A sample of rock has been taken which contains both potassium and argon in the ratio `1:7`, i.e.,  `("Number of potassium `-14` atoms")/("Number of argon`-40` atoms")=(1)/(2)`  Assuming that  when the rock was fromed no argon `-40` was present in the sample and none has escaped subssequently, determine the age of the rock.