Question

Measurements of Carbon-14 in a skull indicate that 25% of the original amount remain. The half-life of Carbon-14 is 5,730 years. How old is the fossil?

A. 1,432 years old

B. 11,460 years old

C. 5,730 years old

D. 2,865 years old

Answer 1

B i think hope this helped hopefully right

Answer 2

B. 11,460 years old

Step-by-step explanation:

Half-life describes how long it takes for a sample to be reduced by 50%.

Half-Life of Carbon-14

Every isotope of different elements has different half-lives. The question states that the half-life of Carbon-14 is 5,730 years. This means that if there is a 100g sample of Carbon-14, then it will take 5,730 years for the sample to become 50g. Then, it will take another 5,730 for the sample to be reduced to 25g.

Determining Age

So, the age of a sample, or fossil, can be determined based on how many half-lives it has been through. We know that 25% of the sample remains. Starting at 100%, it takes one half-life to reach 50% and then a second half-life to reach 25%. This means that the sample of Carbon-14 has been through 2 half-lives. Since we know the length of the half-life, we can multiply 2 by 5,730 to determine the age of the sample.

• 2 * 5730 = 11460

The fossil is 11,460 years old.