Answer:
1. absolute time
2. radioactive decay
3. radiometric dating
4. relative time
Explanation:
1. geologic time measured in a specific duration of years
2. spontaneous disintegration of the atoms of certain isotopes into new isotopes
3. dating a rock or mineral by measuring the proportions of an original radioactive material and its decay products
4. placing events in chronological order without reference to their ages measured in years
