SMT 314 - Introduction to Cosmology » Fall 2020 » HW 12

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Question #1
A P-P chain reaction has the final products of (mark all correct answers):,,
A.   energy
B.   deuterium
C.   Helium
D.   neutrinos
Question #2
A hydrogen nucleus is but a single __________.
A.   atom
B.   neutron
C.   electron
D.   proton
Question #3
As a protostar is formed from a cloud of gas and becomes a pre-main-sequence star, which of the following does not occur?
A.   The protons begin to fuse.
B.   The cloud contracts due to gravity.
C.   The pressure of the gas increases.
D.   The temperature of the gas increases.
E.   The density of the gas increases.
Question #4
Brown dwarfs emit electromagnetic radiation primarily at _________ wavelengths (use the common name, like x-ray or gamma ray).
A.   infrared
B.   microwaves
C.   radio waves
D.   ultraviolet
Question #5
Forms of the same element having different numbers of neutrons are called ________.
A.   isotope
B.   protons
C.   atom
D.   compound
Question #6
Nuclear reactions occur throughout almost the entire Sun, interior to the photosphere, because of the high temperature of the gas everywhere within the Sun.
A.   FALSE
B.   TRUE
Question #7
Pre-main-sequence stars generate energy (heat) predominantly through the process of [a] (two words). Hint: Jupiter, Saturn & Neptune do the same thing to create internal heat, and it's not nuclear fusion, because planets can't do that.
A.   gravitational contraction
B.   gravitational expansion
C.   gravitational force
D.   gravitational collapse
Question #8
The Sun produces most of its energy through a set of reactions known as the [a]-[b] [c].
A.   proton-proton-chain
B.   proton-neutron-chain
C.   proton-neutron-bond
D.   proton-proton-bond
Question #9
What parameters must be equal to obtain hydrostatic equilibrium? (Choose all correct answers),,
A.   temperature
B.   mass
C.   pressure
D.   gravity
Question #10
Which one of the following statements about the birth of stars is false?
A.   Contracting balls of gas with masses below about 75 Jupiter masses actually end up as brown dwarfs, not main-sequence stars.
B.   Gravitational contraction of a pre-main-sequence star ceases once nuclear reaction begin.
C.   During gravitational contraction, the temperature in the core of a pre-main-sequence star decreases.
D.   Stars form from gaint clouds of gas and dust whose collapse and fragmentation (clumping) are due to gravity.
Question #11
Why is it best to view interstellar clouds in infrared or radio wavelengths?
A.   those wavelengths can see the coronas of new stars.
B.   those wavelengths can see the hot stars behind the dust .
C.   those wavelengths are best to view very dim nebulae.
D.   those wavelengths can travel farther distances and see far away.
Question #12
The number of protons, neutrons, and electrons in a neutral atom of is, respectively (A neutral atom is one that has the same number of protons & electrons. In other words, it is not an ion.)
A.   26, 30, 26
B.   30, 26, 26
C.   26, 30, 56
D.   26, 56, 26
E.   30, 26, 30

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