How many particles are in 400 grams of NaCl

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

If two objects at different te,peraure are in contact with each other what happens to their temperature

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.