In an Unweathered Sample of Rock,the Ratio of an Unstable

question 43

Multiple Choice

In an unweathered sample of rock,the ratio of an unstable isotope to its stable daughter isotope is 1:15.If no daughters were present at the time the rock cooled below closure temperature,and the half-life of the isotope is 50 million years,how old is the rock?

• A)200 million years
• B)400 million years
• C)750 million years
• D)1 billion years

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