Radioactive dating uses which concept to determine age?

Radioactive dating uses which concept to determine age?

• A. Using the position of stars to estimate age
• B. Measuring sediment layers only
• C. The use of half-lives to determine the age of a sample
• D. Radiocarbon dating of all materials

Answer: (C)

The essential idea is that radioactive dating relies on the predictable decay of unstable atomic nuclei, tracked by half-lives. A half-life is the time required for half of the original radioactive atoms in a sample to decay into a daughter product. By measuring how much of the parent isotope remains and knowing its half-life, you can calculate how long the decay has been occurring. This works because the rate of decay is constant for a given isotope, allowing us to convert the observed proportion of remaining parent to an elapsed time using the decay equation. In practice, you compare the current amount of the parent to what you started with and use the known half-life to solve for age. For example, if half of the original parent has decayed after two half-lives, the sample is twice the half-life age old. This method provides an absolute age, not just a sequence of events. Other ideas don’t fit as well. Estimating age from star positions relates to astronomical dating rather than dating the material itself. Relying only on sediment layers gives relative timing, not a specific numerical age. Radiocarbon dating isn’t universal for all materials; it applies mainly to carbon-containing samples within a certain age range, and other isotopes are used for different materials and times.

The essential idea is that radioactive dating relies on the predictable decay of unstable atomic nuclei, tracked by half-lives. A half-life is the time required for half of the original radioactive atoms in a sample to decay into a daughter product. By measuring how much of the parent isotope remains and knowing its half-life, you can calculate how long the decay has been occurring. This works because the rate of decay is constant for a given isotope, allowing us to convert the observed proportion of remaining parent to an elapsed time using the decay equation.

In practice, you compare the current amount of the parent to what you started with and use the known half-life to solve for age. For example, if half of the original parent has decayed after two half-lives, the sample is twice the half-life age old. This method provides an absolute age, not just a sequence of events.

Other ideas don’t fit as well. Estimating age from star positions relates to astronomical dating rather than dating the material itself. Relying only on sediment layers gives relative timing, not a specific numerical age. Radiocarbon dating isn’t universal for all materials; it applies mainly to carbon-containing samples within a certain age range, and other isotopes are used for different materials and times.