Question : 41.What force(s) responsible for the collapse of an interstellar cloud?A.nuclearB.gravityC.electricD.magneticE.both : 1777240

41.What force(s) are responsible for the collapse of an interstellar cloud?
A.nuclear
B.gravity
C.electric
D.magnetic
E.both c and d

42.Star clusters are important to the study the stellar evolution because stars in a given cluster have the same
A.temperature.
B.mass.
C.age.
D.luminosity.

43.Why do higher mass stars live shorter lives on the main sequence than lower mass stars?
A.Higher mass stars burn through their nuclear fuel faster.
B.Lower mass stars don't get their energy from that same nuclear fusion source as higher mass stars.
C.Higher mass stars have less hydrogen fuel to burn.
D.Lower mass stars spend a longer time evolving to the main-sequence.
E.All of the above are false.

44.Why do nuclear fusion reactions only take place in the interior of a star?
A.The magnetic fields are strongest there.
B.The temperature is the hottest in the center.
C.The density of material is very high in the center.
D.Both (b) and (c)
E.FALSE; Nuclear fusion reactions can take place in the core and corona where temperatures are high enough.

45.What characteristic of a star primarily determines its location on the main sequence?
A.age
B.distance from the galactic center
C.mass
D.space motion
E.radius

46.The proton-proton chain
A.combines two hydrogen nuclei to produce a single helium nucleus and energy.
B.splits a helium nucleus to produce 4 hydrogen nuclei and energy.
C.is the mechanism that increases the temperature between the photosphere and corona of the sun.
D.is the interactions between protons in Earth's atmosphere that produces auroras.
E.produces energy in the core of the sun in the form of gamma-rays, positrons, and neutrinos.

47.Helioseismology shows that deeper layers of gas in the sun rotate at different speeds. When different parts of an object rotate at different rates it is called
A.the dynamo effect.
B.lagging.
C.reconnection.
D.differential rotation.
E.the Zeeman effect.

48.The sun creates its energy by the process of
A.nuclear fission.
B.nuclear fusion.
C.convection.
D.conduction.
E.radiation.

49.The proton-proton chain needs high temperature because
A.of the ground state energy of the hydrogen atom.
B.of the presence of helium atoms.
C.the protons must overcome the Coulomb barrier.
D.of the need for low density.
E.the neutrinos carry more energy away than the reaction produces.

50.Which of the following is suggested as the best explanation of the missing solar neutrinos?
A.The sun is fusing helium but not hydrogen.
B.Nuclear reactions do not produce neutrinos as fast as theory predicts.
C.The sun may contain matter we haven't yet identified.
D.Neutrinos may oscillate between three different flavors.
E.None of the above

51.In the proton-proton chain
A.no neutrinos are produced.
B.energy is released because a helium nucleus has a greater mass than a hydrogen nucleus.
C.no photons are produced.
D.carbon serves as a catalyst for the nuclear reaction.
E.energy is produced in the form of gamma rays and the velocity of the created nuclei.

52.The capture of too few solar neutrinos by Davis in the solar neutrino experiment
A.has been disproved by the results of later experiments.
B.can be explained if the sun is not undergoing thermonuclear fusion of hydrogen in its core.
C.indicates that the sun's core is much hotter than expected.
D.indicates that the sun's core is convective.
E.none of the above