It is known that one gram of carbon from a living plant which contains a definite proportion of carbon-14 decays at a rate of 15 disintegration per minute. a specimen which was formed from a living plant a long time ago shows 15 disintegration every 4 minutes from one gram of carbon present in it.
Given that the count rate from carbon-14 begins to fall only when tree dies, estimate the age of the specimen. (the half life of carbon-14 is 5000 years)
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Answer:
Specimen is now at15 disintegrations/4 min
Starting from 15 disintegrations / min when it was still living
After one half life:
it would have been 15 disintegrations per 2 minutes
After a 2nd half life:
15 disintegrations per 4 minutes
Thus, the specimen had went through 2 half lives.
So 5000*2 = 10000 years
