Chapter 39, Problem 20A

To determine

The reason for carbon dating method useless for old coins but not for old pieces of adobe bricks.

Explanation of Solution

Introduction:

The amount of the carbon reduces with time due to radioactive process. The process of predicting the age of object because of present amount of the carbon in the object is called the carbon dating.

The age of all the objects can be found that consist the carbon in its chemical composition. If the carbon is not present in the object then the age of the object cannot be predicted.

The amount of the carbon in old metal coins is absent. So, the age of old coins cannot be found by using carbon dating. The adobe bricks consists the amount of carbon, so the method of carbon dating is useful for age prediction.

Conclusion:

Thus, the carbon dating is useless in dating old coins because the old coins are made of metals and the carbon is absent in the metal coins.