Number 8 pls

What does x represent in the formula for the compound xcl4?

Iron (3) oxide will decompose in the presence of hydrogen gas and heater to produced iron and digydrogen monoxide white a balanced chemical equation

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.