Question

Which pair of elements can be used to determine the age of a fossil that is over one billion years old?

lead, which is radioactive, and uranium, which is stable
carbon, which is radioactive, and nitrogen, which is stable
argon, which is radioactive, and lead, which is stable
potassium, which is radioactive, and argon, which is stable

Answer 1

The answer is D) potassium, which is radioactive, and argon, which is stable

Step-by-step explanation:

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Answer 2

Answer: Option (4)

Explanation: The most efficient radioactive method used for the determination of fossil age which is about one billion years old is the Potassium-Argon method (⁴⁰K-⁴⁰Ar).

Potassium-Argon method is generally used to date fossils which are more than 1.2 billion years old as its half life is almost about 1.2 billion years. Potassium is highly radioactive, which converts into Argon and becomes stable.

Uranium and Carbon are also highly radioactive whereas Lead and Nitrogen are stable elements.

¹⁴C-¹⁴N is not an efficient method as it has a half life of only about 5700 years.

Thus the correct answer is option (4).