Question

which phrase describes the element carbon-14?
○ decays at an unknown rate
○ found in an organisms remains
○ forms from the breakdown of nitrogen-14
○ is measured to determine the age of sedimentary rocks

Explanation:

• Option 1: Carbon - 14 has a known half - life (decay rate), so this is incorrect.
• Option 2: Carbon - 14 is present in the remains of once - living organisms (organic matter), and this is a key characteristic related to radiocarbon dating.
• Option 3: Carbon - 14 is formed from the interaction of cosmic rays with nitrogen - 14 in the atmosphere, not from the breakdown of nitrogen - 14.
• Option 4: Carbon - 14 dating is used for dating organic materials (like fossils), not sedimentary rocks (which are dated using other methods like radiometric dating with elements like uranium - lead for rocks).

Answer:

B. found in an organism's remains