How many electrons are in the outermost energy shell of a calcium atom?

Which characteristics can be used to differentiate star systems? check all that apply.

The bohr model of the atom explained why emission spectra are discrete. it could also be used to explain the photoelectric effect. which is a correct explanation of the photoelectric effect according to the model?

Elaborate on the reason(s) that matter is said to move even as in a solid state. select one: a. the particles are bound through intermolecular forces but are able to move past each other with relative freedom. b. the particles have sufficient energy to become an ionized gas and are in the most common state of matter in the universe. c. the particles are not able to move out of their positions relative to one another, but do have small vibrational movements. d. the particles are not bound to one another, move quickly, have a low density, and are able to spread apart from one another if unconstrained.