Q.

The ratio of C14C12 in a piece of wood is 18 part that of atmosphere. If half life of C14 is 5730 years, the age of wood sample is ______ years.                 [2024]


Ans.

(17190)

                C14 is radioactive and undergoes first order decay. In a piece of wood amount of C14 decreases because of radioactive decay but amount of C12 remains same. So if ratio of C14C12 in a piece of wood is 18, this implies ratio of amount C14 remained in the wood to the initial amount is 18.

                In first order reaction equal percentage of reaction is completed in equal time interval. Thus concentration gets halved after every t1/2.

                1t1/212t1/214t1/218

                To get to (18)th value of initial amount, it takes 3t1/2 time i.e.

                3×5730years=17190years