Why do you have to we use carbon-14 to measure the half-life of a decaying tree? (1 point)

Question

All once-living things contain carbon-14 and
• the amount begins to increase when the tree dies.
All once-living things contain carbon-14 and the amount begins to decrease when the tree dies.
All once-living things contain uranium-238 and
• the amount begins to increase when the tree dies.
All once-living things contain uranium-238 and the amount begins to decrease when the tree dies.

Answer 1

The correct answer is:

All once-living things contain carbon-14 and the amount begins to decrease when the tree dies.

Carbon-14 is a radioactive isotope that is present in the atmosphere and absorbed by living organisms. When an organism dies, it stops taking in carbon-14, and the existing carbon-14 in its tissues begins to decay at a known rate, allowing scientists to measure the time since death by assessing the remaining amount of carbon-14.