Which is correct about the effectiveness of carbon dating?
A. It only works for rocks that formed more than about 6,000 years ago
B. It only works for organisms that died less than about 6,000 years ago
C. It only works for rocks that formed more than about 60,000 years ago
D. It only works for organisms that died less than about 60,000 years ago
D. It only works for organisms that died less than about 60,000 years ago
The correct answer is D. It only works for organisms that died less than about 60,000 years ago. Carbon dating is effective for determining the age of organic materials, such as bones, wood, and charcoal. It relies on measuring the amount of carbon-14 present in the sample, which decays at a predictable rate over time. However, carbon dating is not accurate for materials that are older than approximately 60,000 years because the remaining carbon-14 levels become too low to measure accurately.
To determine the correct answer about the effectiveness of carbon dating, we need to understand how carbon dating works. Carbon dating is a method used to estimate the age of organic materials, such as bones or artifacts, based on the decay of radioactive carbon isotope (carbon-14).
Carbon-14 is a naturally occurring isotope that is continuously produced in the Earth's atmosphere. When an organism is alive, it absorbs carbon-14 along with other forms of carbon from the environment. However, once the organism dies, it no longer takes in carbon-14. Over time, the carbon-14 in the organism's remains will gradually decay, and the ratio of carbon-14 to carbon-12 will decrease.
Now let's evaluate the given statements to determine which one is correct:
A. It only works for rocks that formed more than about 6,000 years ago.
This statement is incorrect since carbon dating is primarily used for estimating the age of organic materials, not rocks. Carbon dating is ineffective for dating rocks because rocks do not absorb carbon-14 from the atmosphere.
B. It only works for organisms that died less than about 6,000 years ago.
This statement is incorrect as well. Carbon dating can be used to estimate the age of organic materials that died within the last 50,000 years. After about 50,000 years, there is not enough carbon-14 left in the remains for accurate dating.
C. It only works for rocks that formed more than about 60,000 years ago.
This statement is incorrect for the same reason as statement A. Carbon dating does not work for rocks, so the age of rocks cannot be estimated accurately using this method.
D. It only works for organisms that died less than about 60,000 years ago.
This statement is correct. Carbon dating is most effective for estimating the age of organic materials that died between approximately 500 and 50,000 years ago. After about 50,000 years, the amount of carbon-14 left in the remains becomes too minuscule for accurate dating.
Therefore, the correct answer is option D: It only works for organisms that died less than about 60,000 years ago.