Different isotopes are useful in different dating processes. Suppose we wished to determine the age of an object which we suspect to be approximately 10,000 years old. An isotope with which of the following half-lives would be most appropriate for this project?

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Isotopes with longer half-lives are useful for dating objects that are much older, such as rocks or fossils. Isotopes with shorter half-lives are useful for dating more recent events, such as the age of a tree or a human artifact. Of the choices given, isotopes with half-lives of 50 or 500 years would be too short, as they would not have decayed enough to provide an accurate age measurement for a 10,000 year old object. The isotope with a half-life of 50,000 years would be useful for dating objects millions of years old, but may not provide enough precision for a 10,000 year old object. The best choice would be an isotope with a half-life of 5,000 years, as it falls in the range that would be appropriate for dating an object of this age.

Different Isotopes Are Useful in Different Dating Processes