Astronomy Exam 2 Part 2
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In a supernova explosion
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A. the star may shine as brightly as billions of stars.
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B. elements heavier than iron are formed.
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C. material that later formed the Earth and us humans was distributed between the stars
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D. matter is ejected at tens of thousands of kilometers per second.
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E. All of the above.
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There’s so much to learn about the universe because it continues to change and has very mysterious things. For example there is a mysterious form of matter that cannot be detected by normal means. The Astron 100 class gives you a lot of information about our universe. Test out what you know by taking the test below.
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- 2.
The most important characteristic of a star for determining its lifetime is its
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A. temperature
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B. color
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C. distance from the main sequence
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D. radius
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E. mass
Correct Answer
A. E. massExplanation
The most important characteristic of a star for determining its lifetime is its mass. The mass of a star determines its internal pressure and temperature, which in turn determines the rate at which nuclear fusion reactions occur in its core. These fusion reactions provide the energy that allows a star to shine. A star with a higher mass will have a higher core temperature and a faster rate of fusion, leading to a shorter lifetime. Conversely, a star with a lower mass will have a lower core temperature and a slower rate of fusion, resulting in a longer lifetime. Therefore, the mass of a star is crucial in determining how long it will live.Rate this question:
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- 3.
Which of the following nuclear fuels does an one solar mass star use over the course of its entire evolution?
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A. hydrogen and helium
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B. hydrogen
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C. hydrogen, helium and carbon
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D. hydrogen, helium, carbon, and neon
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E. hydrogen, helium, carbon, neon, and oxygen
Correct Answer
A. A. hydrogen and heliumExplanation
A one solar mass star primarily uses hydrogen as its nuclear fuel during the main sequence phase of its evolution. As hydrogen fuses into helium in the star's core, it releases a tremendous amount of energy through nuclear fusion reactions. This process continues until the hydrogen in the core is depleted. At this point, the star begins to evolve and expand, and helium fusion starts to occur in the core. However, the primary nuclear fuels used over the entire evolution of a one solar mass star are hydrogen and helium.Rate this question:
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- 4.
Which of the following stars is most dense?
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A. a supergiant star
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B. a white dwarf
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C. a main sequence star
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D. a giant star
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E. the sun
Correct Answer
A. B. a white dwarfExplanation
A white dwarf is the correct answer because it is the remnant core of a star that has exhausted its nuclear fuel. It is very dense because it has a mass similar to that of the Sun but is compressed into a much smaller volume, about the size of Earth. This high density is a result of gravitational forces that are no longer balanced by the outward pressure from nuclear fusion.Rate this question:
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- 5.
Which of the following can escape from inside the event horizon of a black hole?
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A. particles of matter.
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B. particles of antimatter.
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C. visible light.
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D. X-rays.
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E. None of the above.
Correct Answer
A. E. None of the above.Explanation
Particles of matter, particles of antimatter, visible light, and X-rays cannot escape from inside the event horizon of a black hole. The event horizon is the boundary beyond which nothing, not even light, can escape the gravitational pull of the black hole. Therefore, any form of matter or energy that crosses the event horizon is trapped inside the black hole, making the correct answer E. None of the above.Rate this question:
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- 6.
A white dwarf is supported against collapse by
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A. neutron drip.
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B. neutrino pressure.
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C. electron degeneracy pressure.
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D. neutron degeneracy pressure.
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E. a central black hole.
Correct Answer
A. C. electron degeneracy pressure.Explanation
A white dwarf is supported against collapse by electron degeneracy pressure. This is because the white dwarf is composed of degenerate matter, where electrons are packed so tightly that they cannot occupy the same quantum state, leading to an increase in pressure. This pressure counteracts the force of gravity, preventing the white dwarf from collapsing further. Neutron drip, neutrino pressure, neutron degeneracy pressure, and a central black hole do not play a role in supporting a white dwarf against collapse.Rate this question:
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- 7.
Which element from the following list does not liberate energy when ”burned” via nuclear fusion in the center of a star?
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A. helium
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B. carbon.
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C. iron.
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D. silicon.
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E. neon.
Correct Answer
A. C. iron.Explanation
Iron does not liberate energy when burned via nuclear fusion in the center of a star because it is the most stable element with the highest binding energy per nucleon. Fusion reactions involving iron require more energy to occur than they release, making it an end point for nuclear fusion in stars.Rate this question:
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- 8.
Which of the following is true of pulsars?
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A. They have very strong magnetic fields.
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B. They rotate very rapidly.
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C. They are neutron stars.
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D. They have a density approximately equal to the density of an atomic nucleus.
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E. All of the above are true.
Correct Answer
A. E. All of the above are true.Explanation
All of the statements A, B, C, and D are true regarding pulsars. Pulsars have very strong magnetic fields, they rotate very rapidly, they are neutron stars, and they have a density approximately equal to the density of an atomic nucleus. Therefore, the correct answer is E, All of the above are true.Rate this question:
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- 9.
A neutron star is expected to spin rapidly because
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A. it has high orbital velocities.
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B. it has high densities.
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C. it has high temperatures.
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D. it conserved angular momentum when it collapsed.
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E. the energy from the supernova explosion that formed them made them spin faster.
Correct Answer
A. D. it conserved angular momentum when it collapsed.Explanation
When a neutron star forms, it is a result of a massive star collapsing under its own gravity. As the star collapses, its angular momentum is conserved, which means that the rotational speed increases. This is similar to an ice skater spinning faster when they pull their arms in. Therefore, the correct answer is D, it conserved angular momentum when it collapsed.Rate this question:
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- 10.
If two stars have the same spectral type, then they must have approximately the same
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A. mass.
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B. parallactic distance.
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C. surface temperature.
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D. chemical composition.
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E. luminosity.
Correct Answer
A. C. surface temperature.Explanation
If two stars have the same spectral type, it means that they have similar patterns of spectral lines, indicating that they have similar surface temperatures. The spectral type of a star is determined by its surface temperature, so if two stars have the same spectral type, it implies that they have approximately the same surface temperature. The other options, such as mass, parallactic distance, chemical composition, and luminosity, are not necessarily related to the spectral type of a star.Rate this question:
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Aug 22, 2024Quiz Edited by
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Apr 29, 2010Quiz Created by
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