Hello. This question is incomplete. The full question is:
"Which characteristic of potassium makes it useful for dating rocks?
It has a long half-life.
It decays at an unknown rate.
It produces lead as it breaks down.
It can be used to date all types of rock."
Answer:
It has a long half-life.
Step-by-step explanation:
The half-life of a radioactive element is the time interval in which a sample of that element is halved. This time interval is also called the semi-disintegration period.
As the radioactive elements disintegrate, over time, their quantity and activity are reduced and, consequently, the amount of energy emitted by it, due to radioactivity, is also reduced.
Potassium has a very long half-life and this makes potassium a perfect element for dating rocks.