Show Para
Hide Para
Paragraph for Questions 27–29: C is absorbed by living organisms during photosynthesis. The
C content is constant in living organism once the plant or animal dies, the uptake of carbon dioxide by it ceases and the level of
C in the dead being, falls due to the decay which
C undergoes
C →
N+β− The half-life period of
C is 5770 years. The decay constant (λ) can be calculated by using the following formula λ =
The comparison of the
β− activity of the dead matter with that of the carbon still in circulation enables measurement of the period of the isolation of the material from the living cycle. The method however, ceases to be accurate over periods longer than 30,000 years. The proportion of
C to
C in living matter is 1 :
1012.
Solution:
Fossils are the geological remains of a once-living organism. To calculate the age of fossils carbon dating method is used. Carbon- 14 is used to determine the age of fossils. The formation of
614C by neutron capture takes place in the upper atmosphere. This
614C is absorbed by living organisms.
714N+01n→614C+11H Since
614C keeps decaying along with regular intake, its content stays constant in living organisms. Once the plant or animal dies, the uptake of carbon dioxide by it ceases and the level of
614C in the dead organism falls due to the decay of
614C.
614C→714N+β− The half-life period of
614C is
5760yr so decay constant can be calculated by using the formula
λ= The comparison of the
β - activity of the dead matter with that of the carbon still in circulation gives us the idea of the period of the isolation from the living cycle.
Carbon dating method is useful to determine the age of the fossils that are 6000 years or more old.
© examsnet.com