ConcepTest: What percentage of parent isotopes remain?
Question:
The half-life of a radioactive isotope is 1,000 million years. Scientists testing a rock sample discover that the ratio of parent and daughter isotopes indicates that the rock is 3,000 million years old. What percentage of parent isotopes remain in the sample?
a. 40
b. 25
c. 12.5
d. 5
a. 40
b. 25
c. 12.5
d. 5
Student Responses:
No data yet. The correct response is c.
If you would like to help acquire more Before and After statistics for this example, please contact the authors (see link at top of page).
