When you were young you may have had your own theory about why plants are green. Then, as you learned more, you kept ideas that were correct, but replaced ideas that were incorrect. Atomic theory also changed as scientists improved their understanding. What incorrect idea in Bohr’s understanding of the atom was replaced in later theories? A. Atoms cannot be divided. B. An atom is mostly empty space. C. In an atom, electrons orbit the nucleus like planets orbit the sun. D. An atom includes electrons embedded in a sphere of positive charge.

answer; /// i believe the correct answer is (thrombocytopenia); (a)

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.