Question

What does the term half-life mean when using radioactive dating to determine the age of fossils?

A. Half-life is used to describe half the amount of time it takes for an organism to fossilize in radioactive sediment.

B. Half-life is used to describe the amount of geologic time represented by half of a horizontal layer in radioactive sediment.

C. Half-life is used to describe the amount of time it takes for half of a radioactive substance to decay.

D. Half-life is used to describe half the amount of time it takes for a fossil to become radioactive.

Answer 1

C. Half-life is used to describe the amount of time it takes for half of a radioactive substance to decay.

Explanation: In radioactive dating, scientists measure the amount of a radioactive substance in a fossil or rock and compare it to the amount of its decay product to determine its age. The half-life of a radioactive substance is the amount of time it takes for half of the atoms in a sample to decay into its decay product. By measuring the ratio of the remaining radioactive substance to its decay product, scientists can calculate the age of the fossil or rock