Which property of argon makes it useful for potassium-argon dating?

• A. Argon is naturally abundant in the Earth's atmosphere.
• B. Argon has a high atomic mass compared to potassium.
• C. Argon is a noble gas and does not chemically react with other elements.
• D. Argon is highly soluble in water.

Answer: (C)

Verified step by step guidance

1. Understand the context of potassium-argon dating: it is a radiometric dating method used to determine the age of rocks by measuring the amount of argon gas produced from the radioactive decay of potassium-40.
2. Recognize that for potassium-argon dating to be accurate, the argon produced must remain trapped in the rock and not react chemically or escape easily.
3. Identify the key property of argon that makes it suitable: argon is a noble gas, meaning it is chemically inert and does not react with other elements or compounds.
4. Because argon does not chemically react, it remains trapped within the mineral structure after being produced by radioactive decay, allowing accurate measurement of its concentration.
5. Conclude that the chemical inertness (non-reactivity) of argon is the crucial property that makes it useful for potassium-argon dating.