Help me with my chem, multiple choice:)

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5

If 22.5 liters of oxygen reacted with excess of hydrogen, how many liters of water vapor could be produced?

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.