How many electrons are there

At 300 mm hg, a gas has a volume of 380 l, what is the volume at standard pressure

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.

All motion is caused by force? true or false