Question

The technique known as potassium-argon dating is used to date old lava flows. The potassium isotope, ^40K has a 1.28 billion year half-life and is naturally present at very low levels. ^40K decays by beta emission into ^40Ar. Argon is a gas, and there is no argon in flowing lava because the gas escapes. Once the lava solidifies, any argon produced in the decay of ^40K is trapped inside and cannot escape. A geologist brings you a piece of solidified lava in which you find the ^40 Ar/^40K ratio to be 0.350. What is the age of the rock?

Answer 1

Pty 0-35 apsb den A, = 035 k o 693 110 35 moe 108 6.541t 0,74077% % е 0.5 0554 Billion yeans tny