If You Obtained a Sample of Rock from Venus and Determined

question 27

Multiple Choice

If you obtained a sample of rock from Venus and determined the abundances of ²³⁸U and ²⁰⁷Pb in it,and found that for every one uranium atom there were three lead atoms,then what would the age of this rock be? Note that ²³⁸U decays to ²⁰⁷Pb with a half-life of 700 million years.Assume that there was no ²⁰⁷Pb in the rock when it originally formed.

• A) 1.4 billion years
• B) 2.8 billion years
• C) 230 million years
• D) 4.5 billion years

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