Answer:
<u><em>1. Igneous. 2. Unstable. 3. Constant. 4. Stable.</em></u>
Explanation:
Geologists determine absolute age by comparing the amounts of radioactive and nonradioactive elements in igneous rock. The radioactive, or unstable elements decay into nonradioactive elements. Because this rate of decay is constant for each element, geologists can compare the amounts of stable and unstable elements to determine how much of the stable elements have formed over time.
Explanation:
The method used by geologists in calculating the precise or absolute age of a fossil is called radiometric dating. This calculation is done by measuring the amount of energy emitted by some radioactive elements present in the igneous rocks.
Each element with radioactive properties has a constant decay rate of its radiation, which is the amount of radioactivity that it loses over time. After the necessary time, radioactive or unstable elements become stable particles.
Since each element has a constant decay rate, the time that has elapsed since its formation can be estimated.
Although fossils are normally found in sedimentary rock strata -which do not contain radioactive elements- their precise age is calculated using radiometric dating of adjacent igneous rock strata.
Learn more:
Radiometric dating brainly.com/question/2833014
