You need 2.5 mol of iron (fe) for an experiment. how many grams of iron must you measure out?

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change?

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.

Answer asap : ( a. how does mucus prevent the entry of pathogens? b. describe two ways white blood cells protect us from pathogens.