The Mystery of the Age of an Igneous Rock Revealed

What is the approximate age of the igneous rock based on the given data?

The approximate age of the rock is 2.5 billion years.

Understanding the Data

The half life of potassium 40 is approximately 1.25 billion years, which means that in each 1.25 billion years, half of the original mass of potassium 40 will decay into argon 40. So, if an igneous rock is found to contain about 1/4 of its original mass of potassium 40, it indicates that two half-lives have occurred. This means that the rock must be 2.5 billion years old. Calculation: - After the first half-life (1.25 billion years), the rock would contain 1/2 of its original mass of potassium 40. - After the second half-life (another 1.25 billion years), the remaining 1/2 of the original mass of potassium 40 would be halved again, resulting in 1/4 of the original mass. This calculation aligns with the data given and confirms that the approximate age of the igneous rock is indeed 2.5 billion years.

Conclusion

In conclusion, by understanding the concept of half-life and decay of potassium 40 into argon 40, we can accurately determine the age of a rock based on its potassium 40 content. In this case, the igneous rock with 1/4 of its original mass of potassium 40 is estimated to be 2.5 billion years old. This shows the importance of utilizing scientific principles and data analysis to reveal the mysteries of the Earth's geological history.
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