Scientists have discovered a moon rock, and they determine that there is about 50% of uranium remaining. Use the reference diagram to determine the age of the moon rock. Explain your answer.
To determine the age of the moon rock, we can use the concept of radioactive decay. Uranium-238 decays into lead-206 with a half-life of 4.5 billion years. Since the moon rock contains 50% uranium, we can assume that half of the original uranium has decayed into lead-206.
Based on the diagram:
- 50% uranium remaining corresponds to 0.5 N
- 50% uranium decayed corresponds to 0.5 D
This means that the ratio of parent uranium to daughter lead is 1:1. From the diagram, we can see that this corresponds to 1 half-life (t1/2) or 4.5 billion years.
Therefore, the age of the moon rock is 4.5 billion years. This is the amount of time it would take for 50% of the original uranium to decay into lead-206, as indicated by the diagram.