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Multiple Choice
Determine the age of a bone that has a decay rate of 3.80 dis/min ⋅ g C if the ratio of 12C:14C in living organisms has a decay rate of 15.3 dis/min ⋅ g C. (t1/2 of 14C = 5730 years).
A
1.39 × 104 yr
B
1.15 × 104 yr
C
2.30 × 104 yr
D
1.39 yr
E
1.15 yr
Verified step by step guidance
1
Understand that the problem involves radioactive decay, specifically the decay of carbon-14 (14C) in a bone sample. The decay rate is given in disintegrations per minute per gram of carbon (dis/min · g C).
Use the decay rate of 14C in living organisms (15.3 dis/min · g C) as the initial activity (A0) and the decay rate in the bone (3.80 dis/min · g C) as the current activity (A).
Apply the radioactive decay formula: A = A0 * e^(-λt), where λ is the decay constant and t is the time elapsed. Rearrange the formula to solve for t: t = (1/λ) * ln(A0/A).
Calculate the decay constant (λ) using the half-life formula: λ = ln(2) / t1/2, where t1/2 is the half-life of 14C (5730 years).
Substitute the values of A0, A, and λ into the rearranged decay formula to calculate the age of the bone (t).