Which isotope is appropriate for dating rocks that are billions of years old a. carbon-12 b. carbon-14 c. uranium-238 d. oxygen-16

Option (C)

Explanation: Uranium- 238 is an unstable isotope of uranium. It is one of the most effective isotope used for radioactive dating in order to determine the age of a rock that is about billions of years old. It contains an unstable nucleus that undergoes continuous decay, until it reaches a stable environment. It has a half life of approximately 4.5 billion years and majority of the uranium that are present on earth at present are all uranium- 238 and they are constantly decaying. When uranium completely decays, it then gets converted into lead, which is a stable element.

The most common radioactive method used to date rocks is Uranium-Lead dating method.

Thus, the correct answer is option (C).