Suppose You Find a Rock That Contains 10 Micrograms of Radioactive

question 117

Multiple Choice

Suppose you find a rock that contains 10 micrograms of radioactive potassium-40, which has a half-life of 1.25 billion years. By measuring the amount of its decay product (argon-40) present in the rock, you conclude that there must have been 80 micrograms of potassium-40 when the rock solidified. How old is the rock?

• A) 3.75 billion years
• B) 1.25 billion years
• C) 2.5 billion years
• D) 5.0 billion years

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Definitions:

Highly Fractured Granite

Granite rock that has undergone extensive cracking and breaking, often increasing its permeability and affecting its structural integrity.

Insoluble Material

Substances that cannot dissolve in a solvent, such as water, remaining solid and separated from the liquid mixture.

Drinking Water Standards

Regulatory benchmarks set to ensure the safety and quality of water for human consumption.

Concentration

The amount of a given substance in a specified volume or mass of a solution or mixture.