Question

In the Potassium - Argon system, Potassium breaks down into both Argon and calcium.

Why not use the Potassium - Calcium system?
a. 40Ca derived from Potassium cannot be distinguished for existing 40Ca.
b. Calcium cannot be measured by a mass spectrometer.
c. Potassium cannot be measured by a mass spectrometer.
d. Calcium is lost by pressure.
e. Calcium is too big

Answer 1

The Potassium - Argon system is used for dating rocks based on the decay of potassium into argon. The Potassium - Calcium system is not used for dating because of various reasons.

Step-by-step explanation:

The Potassium - Argon system is used for dating nonorganic materials such as rocks because the decay of potassium into argon can be measured. Potassium-40 decays by positron emission and electron capture to form Argon-40 with a half-life of 1.25 billion years. The age of a rock can be determined by measuring the amount of Argon-40 gas that escapes from the rock sample.

In contrast, Potassium - Calcium system is not used for dating because:

1. 40Ca derived from Potassium cannot be distinguished from the existing 40Ca in the environment.
2. Calcium cannot be measured by a mass spectrometer.
3. Calcium is lost under pressure.
4. Calcium is a larger atom compared to Argon, making it more difficult to measure accurately.