A rock was found to have 25 per cent potassium-40 remaining - VCE - SSCE Biology - Question 12 - 2002 - Paper 1
Question 12
A rock was found to have 25 per cent potassium-40 remaining.
The approximate age of the rock is
A. 0.65 million years.
B. 1.3 million years.
C. 2.6 million years.
D.... show full transcript
Worked Solution & Example Answer:A rock was found to have 25 per cent potassium-40 remaining - VCE - SSCE Biology - Question 12 - 2002 - Paper 1
Step 1
Determine the Remaining Potassium-40
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Given that 25% of potassium-40 remains, this indicates the rock has completed three half-lives of decay, as each half-life reduces the quantity of potassium-40 by half.
Step 2
Calculate the Age of the Rock
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The half-life of potassium-40 is approximately 1.3 million years. Hence, the total age of the rock can be estimated as follows:
