You have 1 mole of a substance, and it has a mass of 142 g. after some analysis, you determine that it is ionic, but you do not know what the substance is. All you do know of the formula is X2SO4. What is the density of the unknown substance, X?

Which theory was contradicted by experiments with the photoelectric effect? light spreads out after it passes through a small opening. as soon as light strikes metal, electrons will be ejected. visible light, regardless of color, will cause the ejection of electrons when striking metal. the kinetic energy of ejected electrons depends on the frequency of light that strikes the metal.