Which of the following radioactive substances is commonly used to date very ancient (older than the Cenozoic) fossils and events in the history of life?

Question

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Potassium-40 is commonly used to date very ancient fossils and events in the history of life, as it has a much longer half-life compared to carbon-14. The decay of potassium-40 into argon-40 is used to determine the age of rocks and fossils older than the Cenozoic era, which is approximately 66 million years ago.

Which of the Following Radioactive Substances Is Commonly Used to Date