What must be done to calculate the enthalpy of reaction? Check all that apply. The first equation must be halved. The first equation must be reversed. The second equation must be halved. The second equation must be reversed. The third equation must be halved. The third equation must be reversed.

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.