When a solid undergoes it takes up less space due to cooling

What is a possible quantum number set for an electron in the 3s orbital of a magnesium atom

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?

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.