The girlfriend of a phs1282 student proposes to him and offers him a "golden" ring in the process. however, his girlfriend is a student in the department of accountancy and finance, and would struggle to afford a gold ring. additionally she is known to have a slightly dodgy character. after initially being flattered by the marriage proposal he therefore gets suspicious about whether the ring is actually made of gold. he therefore bring the ring to the phs「282 lab and measure its mass to be 2.80± 0.02 g and its volume to be 0.16 ± 0.03 cm3 . gold has a mass density of 19.3 g/cm3. could the ring be made of gold? (explain your answer) . brass has a mass density of 8.4 g/cm3 to 8.7 g/cm3 (depending on the composition of the alloy). could the ring be made of brass?

Which of the following are considered noble gases? a. bromine b. neon c. argon d. chlorine

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.

Estimate of the number of stars in our galaxy