ROBERTS REVIEW I PHYSICS 10601. The nearest star is over one parsec distant.a. Trueb. False2. The proper motion of a star is its true velocity through space.a. Trueb. False3. The "solar constant" refers to the observation that the Sun's brightness does not ever change.a. Trueb. False4. The 21-centimeter emission of hydrogen is the result of the electron making a transition from its very highest energy level to the next level down.a. Trueb. False5. All else being equal, the hotter a star is, the brighter it will be.a. Trueb. False6. Solar neutrinos, observed on Earth, originate in the solar corona.a. Trueb. False7. Emissions from molecules are the only means we have for determining the conditions inside a molecular cloud.a. Trueb. False8. Spectral type M stars are cooler than type O.a. Trueb. False9. A spectral type A main sequence star is brighter than a type B main sequence star.a. Trueb. False10. The fusion of hydrogen is difficult to produce because four hydrogen atoms must collide simultaneously in order to fuse into helium.a. Trueb. False11. The temperature inside a molecular cloud is typically colder than other interstellar matter.a. Trueb. False12. Interstellar matter is distributed very evenly through the galaxy.a. Trueb. False13. When describing the properties of stars, solar units of mass and radius are often used.a. Trueb. False14. One parsec is a little over 200,000 A.U.a. Trueb. False15. The Sun's density is about the same as Saturn's.a. Trueb. False16. Heavy elements are not seen in interstellar gas because they go into making interstellar dust.a. Trueb. False17. Starlight sometimes is polarized as it passes through the interstellar medium because dustparticles are spherical.a. Trueb. False18. Almost all stars have radii between about 0.1 and 10 times the radius of the Sun.a. Trueb. False19. Star A and star B have the same apparent magnitude. Star A is twice as distant as star B. Therefore, star A has twice the luminosity as star B.a. Trueb. False20. Emission nebulae glow because they absorb ultraviolet light from nearby hot stars.a. Trueb. False21. There are absorption lines seen in the Sun's spectrum corresponding to 83 different elements.a. Trueb. False22. A type G star is hotter than a type K.a. Trueb. False23. A type B star is hotter than a type A.a. Trueb. False24. The chromosphere is faint because of its low density.a. Trueb. False25. Molecular clouds are much warmer than typical interstellar gas clouds.a. Trueb. False26. Dark dust clouds radiate mainly in the radio portion of the electromagnetic spectrum.a. Trueb. False27. A G2 star is cooler than a G3.a. Trueb. False28. Hydrogen lines are weak in both very hot and very cool stars.a. Trueb. False29. Atomic nuclei are held together by the strong force.a. Trueb. False30. A magnitude 2 star is 100 times as bright as a magnitude 12 star.a. Trueb. False31. Why couldn't you stand on the Sun's surface?a. You could stand on the surface.b. The Sun doesn't have a solid surface.c. The Sun's surface is too highly magnetized for anything to survive there.d. You could stand on it, if a sufficiently protective spacesuit could be designed.32. Which of the following best describes the size and distance relationship of our Sun and the nearest star?a. Two beachballs separated by 100 city blocks.b. Two grains of sand separated by 100 light years.c. Two golfballs separated by 100 kilometers.d. Two baseballs separated by 100 yards.33. Why are dark dust clouds largely misnamed?a. They contain much more gas than dust.b. The appearance of a cloud is an illusion; dust is scattered very evenly throughout the Galaxy.c. Dust clouds are not dark but emit significant amounts of visible light. They just look dark compared to the bright stars.d. all of the abovee. none of the above34. How would sunspots appear if you could magically remove them from the Sun?a. Because sunspots are dark spots, they would be invisible against the blackness of space.b. They would shine brightly.c. They would not appear any differently than on the surface of the Sun.d. They would shine only with reflected sunlight.35. Of the many complex molecules found in interstellar space, most are based on which element?a. Hydrogen.b. Silicon.c. Oxygen.d. Carbon.36. What effect does dust have on visible light passing through it?a. It dims and reddens it.b. It completely blocks all visible light from passing through.c. All light is turned bluish in color.d. It makes the light coming from stars appear to twinkle.37. What is the average temperature of interstellar gas and dust?a. 3Kb. 100 Kc. 1,000 Kd. 10,000 Ke. 0 K38. The light we see from the Sun comes from which layer?a. chromosphereb. photospherec. coronad. convective zone39. Which of the following spectral types is the hottest?a. G2.b. G3.c. G4.d. G5.40. The density of interstellar dust is extremely low but it can block starlight because:a. most of this matter is found surrounding stars and not dispersed in the regions between the stars.b. interstellar dust particles are equal in size to wavelengths of visible light.c. there is about 100 times more gas than there is dust.d. interstellar dust particles have elongated shapes.41. What is the meaning of the "solar constant"?a. the regularity of the sunspot cycleb. the surface features of the Sun never changec. the size of the Sun never changesd. the solar energy reaching Earth per unit area per unit timee. the constancy of the proton-proton cycle that produces the energy of the Sun42. Spectra of stars often show narrow absorption lines from interstellar matter. What type of interstellar matter produces these?a. dustb. neutral gasc. ionized gasd. molecules43. Interstellar absorption lines are narrow primarily because:a. there is very little interstellar matterb. molecules always produce narrow absorption linesc. most of the matter is ionizedd. the matter is at a low temperature44. A nearby star has a parallax of 0.2 arc seconds. What is its distance?a. 0.1 pcb. 0.2 pcc. 0.5 pcd. 2 pce. 5 pc45. What information does 21-centimeter radiation provide about the gas cloud that emitted it?a. radial velocityb. densityc. temperatured. all of the abovee. none of the above46. When the chromosphere can be seen during a solar eclipse, what is its color?a. whiteb. bluec. yellowd. greene. red47. What is the net result of the proton-proton chain?a. 2 heliums are fused into 1 carbon, 1 neutrino + energyb. 4 hydrogens are fused into 1 helium, 2 neutrinos + energyc. 2 hydrogens and 1