Question

The half-life of thorium-232 is 14 billion years. A rock with 50% of its thorium-232 remaining is: 3. 5 billion years old. 14 billion years old. 28 billion years old

Answer 1

Answer: 28 billion

Explanation: To get the age of the rock, the half-life of thorium-232, which is 14 billion years, is to be multiplied to the number of half-lives it has passed. The answer is 28 billion.