Why is potassium-argon dating most applicable to dating very old rocks?
potassium’s long half-life
potassium’s short half-life
argon’s long half-life
argon’s short half-life
You want a long half-life for older rocks.
I think it may be argon, but you need to lookup the half-lives of each of them. You can probably google it.
Now, I think it might be Potassium.. I just saw anothr post with K -40 has a half life of approx. 1.25 billion years.
Potassium-argon dating is most applicable to dating very old rocks because of the long half-life of potassium. In this dating method, the ratio of potassium-40 to argon-40 is measured. Potassium-40 has a half-life of about 1.3 billion years, which means that after 1.3 billion years, half of the original potassium-40 in a sample would have decayed into argon-40.
By measuring the amount of potassium-40 and argon-40 in a rock sample, scientists can calculate how long it has been since the rock formed or underwent a geological event. This method is particularly useful for dating rocks that are several million to billions of years old, as the long half-life of potassium allows for the measurement of very small amounts of remaining potassium-40.
On the other hand, the half-life of argon-40 is relatively long as well, which provides a stable and reliable basis for dating older rocks. The combination of a long half-life for both potassium-40 and argon-40 makes potassium-argon dating suitable for determining the ages of very old rocks.