posted by Emily .
Scientists can determine the age of ancient objects by a method called radio carbon dating.
The bombardment of the upper atmosphere
by cosmic rays converts nitrogen to a radioactive isotope 14C of carbon with a half-life of
about 5710 years. Vegetation absorbs carbon dioxide through the atmosphere and animal life assimilates 14C through food chains.
When a plant or animal dies it stops replacing its carbon and the amount of 14C begins
to decrease through radioactive decay. Therefore, the level of radioactivity must also decay
exponentially. A parchment fragment was
discovered that had about 15% as much 14C
radioactivity as does plant material on Earth
Estimate the age of the parchment.
1. t = 15601 years
2. t = 15645 years
3. t = 15628 years
4. t = 15689 years
5. t = 15667 years
2) t=15645 years