Answer B is false. An element is a type of atom and you do not need to combine two atoms to get a specific element. Combining two atoms will leave you with a compound not an element.
Answer;
-Carbon-14 decays into nitrogen-14.
-Once a living thing dies, it no longer takes in carbon.
-Carbon-14 dating works for fossils as old as 50,000 years.
Explanation;
-Geologists do not use carbon-based radiometric dating to determine the age of rocks. Carbon dating only works for objects that are younger than about 50,000 years, and most rocks of interest are older than that.
-Carbon dating is used by archaeologists to date trees, plants, and animal remains; as well as human artifacts made from wood and leather; because these items are generally younger than 50,000 years.
-Carbon-14 has a half life of 5730 years, meaning that 5730 years after an organism dies, half of its carbon-14 atoms have decayed to nitrogen atoms.
Facilitated diffusion therefore allows polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, to cross the plasma membrane. Two classes of proteins that mediate facilitated diffusion are generally distinguished: carrier proteins and channel proteins.
Explanation:
As I think option D is the correct one.
I'm pretty sure that would be the spinal cord. Hope this helps. :)
