Which of the following best defines density? a measure of how much a single particle weighs , , , a measure of how much a single particle weighs , ,

a measure of the amount of particles in a block of a substance , a measure of the amount of particles in a block of a substance , ,

a measure of how much space a block of substance occupies , , , a measure of how much space a block of substance occupies , ,

a measure of the amount of mass in a given amount of space

Match the atomic particles with their characteristics. 1. made of two protons and two neutrons neutron 2. similar to an electron; positive charge neutrino 3. orbits nucleus; negative charge positron 4. bundle of energy; zero charge proton 5. found in nucleus; positive charge meson 6. very unstable; +, -, or zero charge gamma 7. found in nucleus; zero charge electron 8. negative particle; negative charge beta 9. atomic energy converted to mass alpha

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

Some material consisting of a collection of microscopic objects is kept at a high temperature. a photon detector capable of detecting photon energies from infrared through ultraviolet observes photons emitted with energies of 0.3 ev, 0.5 ev, 0.8 ev, 2.0ev, 2.5ev, and 2.8ev. these are the only photon energies observed. (a) draw and label a possible energy-level diagram for one of the microscopic objects, which has four bound states. on the diagram, indicate the transitions corresponding to the emitted photons. explain briefly. (b) would a spring–mass model be a good model for these microscopic objects? why or why not? (c) the material is now cooled down to a very low temperature, and the photon detector stops detecting photon emissions. next, a beam of light with a continuous range of energies from infrared through ultraviolet shines on the material, and the photon detector observes the beam of light after it passes through the material. what photon energies in this beam of light are observed to be significantly reduced in intensity (“dark absorption lines”)? explain briefly.