What is one difference between Group 2 and Group 15 of the Periodic Table of Elements?

When the volume and number of particles of a gas are constant which of the following is also constant

Stage in which a typical star has completely stopped fusion

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.