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Moon Rocks In one of the rocks brought back from the Moon,
Chapter 32, Problem 73GP(choose chapter or problem)
Problem 73GP
Moon Rocks In one of the rocks brought back from the Moon, it is found that 80.5% of the initial potassium-40 in the rock has decayed to argon-40. (a) If the half-life for this decay is 1.20 × 109 years, how old is the rock? (b) How much longer will it take before only 10.0% of the original potassium-40 is still present in the rock?
Questions & Answers
QUESTION:
Problem 73GP
Moon Rocks In one of the rocks brought back from the Moon, it is found that 80.5% of the initial potassium-40 in the rock has decayed to argon-40. (a) If the half-life for this decay is 1.20 × 109 years, how old is the rock? (b) How much longer will it take before only 10.0% of the original potassium-40 is still present in the rock?
ANSWER:
Step 1 of 3
The radioactive decay of potassium- 40 can be used to determine the age of a Moon rock.
The number of radioactive nuclei in a sample is calculated from equation and decay constant from equation 32-10.