Question

question: geologists use the ___ isotope pairs for isotopic dating of samples from 1 million to 4.57 billion years. answer input: spelling counts but capitalization doesnt.

Explanation:

In geological isotopic dating, the uranium - lead (U - Pb) isotope pairs are commonly used for dating samples with an age range from about 1 million to 4.57 billion years. This is because the half - lives of uranium isotopes (such as $^{238}\text{U}$ and $^{235}\text{U}$) decaying to lead isotopes ($^{206}\text{Pb}$ and $^{207}\text{Pb}$ respectively) are very long, making them suitable for dating a wide range of geological time scales, including the age range mentioned.

Answer:

uranium - lead (or U - Pb)