If you obtained a sample of a meteorite and determined the abundances of uranium (²³⁸U) and lead (²⁰⁷Pb) in it, and found that for every 1 uranium atom there were 15 lead atoms, then what would the age of this rock be? Note that this form of uranium decays to this form of lead with a half-life of 700 million years. For simplicity, you can assume that there was no lead in the rock when it originally formed. A) 1.4 billion years B) 2.8 billion years C) 4.0 billion years D) 10.5 billion years E) 3.6 billion years

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Quizplus · Accepted Answer

The ratio of 1 uranium atom to 15 lead atoms suggests that 4 half-lives have passed (since 1:15 implies 1 part uranium to 15 parts lead, meaning 16 total parts, which is 2^4). Each half-life is 700 million years, so 4 half-lives is 2.8 billion years.

If You Obtained a Sample of a Meteorite and Determined