Posted by Sandhya on Sunday, April 20, 2008 at 1:53pm.
Do you have an answer?
Yes. But it is incorrect
R = 1.34 Bq = 1.34 decays / second Mass of sample = 7.02 g
For 14 C T 1/2 = 5700 years (approximate value)
= 5700 x 365 x 24 x 60 x 60 =1.8 x 10 11 seconds
T 1/2 = 0.6931 / λ
λ = 0.6931 / 1.8 x 10 11 = 3.86 x 10 -12 per second
Number of atoms contained in 7.02 g of carbon (12 C atoms)
= (7.02 x 6.023 x 10 23) /14 = 3.02 x 10 23
14 C atoms / 12 C atoms = 1.23 x 10-12
No of 14 C atoms (radioactive) = No of 12 C atoms x 1.23 x 10-12
N0 = 3.02 x 10 23 x 1.23 x 10-12 = 3.7146 x 10 11
R = Nλ
N = R/λ = 1.34 / 3.86 x 10 -12 = 3.4715 x 10 11
t = 3.323 x 5700 x In (3.4715 x 10 11 / 3.7146 x 10 11 ) = 557 years