Is silicon (si) or hydrogen (h) more abundant? i think it's hydrogen, but i can't

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.

The diagram below shows the movement of particles. what does this piece of evidence best support? the collision theory the maxwell-boltzmann distribution the effect of pressure on reaction rates the effect of temperature on reaction rates

Which statement best describes the he properties of iconic compounds ?