Chapter U1.15, Problem 9E

Interpretation Introduction

Interpretation:

Out of the given objects found at an ancient campsite which can be used to determine the age of the site is to be selected and explained.

Concept introduction:

Carbon - 14 is a radioactive isotope of carbon that has a half - life of 5730 years. This means that it will take 5730 years for half of a carbon - 14 sample to decay into nitrogen - 14. This aspect of carbon - 14 is used to detect age of carbon fossil by the process known as carbon dating.

Answer to Problem 9E

The following objects can be used to determine the age of the campsite:

1. An axe with a stone blade and a wooden handle
2. Ashes of a campfire
3. A jawbone of a deer

All these objects have carbon in them so they can be used to find out age of the site through carbon dating.

Explanation of Solution

Radioactive isotopes are unstable. To become stable they eject a particle from the nucleus. The process of ejecting particles from the nucleus of an atom is called radioactive decay.

Carbon - 14 is a radioactive isotope of carbon that has a half - life of 5730 years. This means that it will take 5730 years for half of a carbon - 14 sample to decay into nitrogen - 14 and another 5730 years for remaining half of carbon - 14 to decay. As long as things are alive carbon - 14 builds up to a steady level. When the things die, carbon - 14 starts to decay at this rate.

By measuring the remaining amount of carbon - 14 compared to the amount of stable carbon, the age of the sample can be calculated. This process is known as carbon dating.

Out of the objects obtained from the campsite, those objects that have carbon in them can be used to determine the age of site. All living things have some amount of carbon in them.

1. An axe with a wooden handle can be used as the wood in the handle is made of carbon product. It comes from plant so has carbon - 14 in it.
2. Ashes of a campfire will have carbon in it as some wood/ leaves must have been used to create fire. So it can be used for carbon dating.
3. Jawbones of a deer have carbon - 14. So it can surely be used to determine the age of site.

Clay pot and arrowhead are non - living things so they cannot be used to determine age of the site..

Conclusion

Carbon dating is a useful technique in the hands of scientists to detect age of a fossils, archaeological sites, artifacts and ancient human remains.