Why should scientists perform experiments? a. to understand a hypothesis b. to answer questions about right and wrong c. to answer specific questions d. to impress their coworkers i believe i know the answer i just need it to be explained

Select all of the statements which are true. electrons are located in shells or orbits around the atom. electrons orbit slowly around the atom. electrons travel in one flat path around the nucleus of an atom. the valence of an atom is determined by the number of electrons in the atom's outermost shell.