If a rock contains 70% uranium-238,you would estimate it to be about ____ billion years old.

Question

Quizplus · Accepted Answer

Uranium-238 has a half-life of approximately 4.5 billion years. If a rock contains 70% uranium-238, it means it has not yet reached its first half-life. Since 50% would indicate one half-life (4.5 billion years), a content of 70% suggests the rock is less than 4.5 billion years old. However, there's no direct linear correlation provided in the options that matches exactly with the uranium percentage to age conversion. Among the given options, 6.75 billion years is too high considering the half-life principle. The correct answer should logically be less than 4.5 billion years based on the half-life concept, but given the options and the misunderstanding in the explanation, there seems to be a mistake in reasoning. Uranium-238's decay rate implies that after 4.5 billion years, only 50% of the original uranium-238 would remain. However, none of the options directly correlate to the percentage given, and the explanation mistakenly suggested an answer based on incorrect application of the half-life concept. The correct approach would involve understanding that the percentage of uranium-238 present does not directly translate to a simple linear age estimate without more information on the initial quantity or without a specific formula to calculate the age based on remaining percentage. Therefore, without a direct correlation or calculation method provided, the explanation inaccurately navigated the half-life concept.

If a Rock Contains 70% Uranium-238,you Would Estimate It to Be