Please answer all parts of the question. Thanks in advance. Question: A radioact

Question

Please answer all parts of the question. Thanks in advance.

Question:

A radioactive isotope of Carbon (Chlorine-14) decays to an isotope of Nitrogen (Nitrogen-14) in 5,730 years.

a. Imagine you find a piece of rock in an archaeological site. By analyzing the rock, you find that only 0.78125% of the Carbon-14 originally in the rock remains. How old is the rock?

b. A well-preserved piece of wood at the archaeological site has 18.75% of the Carbon-14 it must have had when it was living. Calculate when the wood was cut.

Explanation / Answer

A. The amount of carbon 14 present in sample is 0.78125%

So the amount of half lives elapsed will be

(1/2) n= 0.0078125

n log 0.5 = log 0.0078125

n = 7

So the length of time elapsed = 7 × 5730 = 40110 yrs

So the rock is 40110 years old.

B. 18.75% of carbon 14 years left in wood

By applying the same formula given above n is calculated

nlog 0.5 = 0.1875

n = 2.41

So the time will be 5730 × 2.41 = 13850 years.

The wood was cut 13850 years ago.

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.