AST 101 - LESSON 10 EXAM QUESTIONS WITH CORRECT ANSWERS LATEST UPDATE 2026
Shown below here is the track on the H-R diagram of a star like the Sun. At Point A the star is -
Answers fusing hydrogen in a shell around a collapsing core.
Submit
From the same H-R diagram above, at Point B, the star is - Answers fusing helium in its core and
hydrogen in a shell.
From the same H-R diagram above, at Point C, the star is - Answers has a stable, inert carbon core
and essentially no hydrogen or helium.
A supernova occurs when - Answers a massive star fuses through successively heavier elements until
it has an iron core, which will not release energy from fusion.
Consider a young globular star cluster where all the cluster stars formed at about the same time. If
you were to observe this star cluster over several billion years, you would see - Answers many
supernovae early on, and then no more.
Why are red giant stars rare compared to main-sequence stars? - Answers The amount of time a red
giant lasts is small compared to the lifespan of a main-sequence star.
Why doesn't a high-mass star fuse its iron into heavier elements, like uranium? - Answers No mass-
energy is released due to the fusion of iron.
In the dying stages of our Sun, it will fuse helium into carbon. After that, what will occur? - Answers
The core contracts, but the carbon never fuses.
Listed following are characteristics that describe either high-mass or low-mass stars. Match these
characteristics to the appropriate category. - Answers High-mass stars:
late in-life fuse carbon into heavier elements
have higher fusion rate during main sequence life
end life as supernova
Low-mass stars:
the Sun is an example
have longer lifetimes
final corpse is a white dwarf
end life as a planetary nebula
Provided following are various stages during the life of a high-mass star. Rank the stages based on
when they occur, from first to last. - Answers contracting cloud of gas and dust, protostar, main
sequence star, red supergiant, supernova, neutron star
Provided following are various elements that can be produced during fusion in the core of a high mass
main sequence star. Rank these elements based on when they are produced, from first to last. -
Answers helium, carbon, oxygen, iron
The diagram indicates that the third most abundant element in the Milky Way Galaxy is _____. -
Answers oxygen
According to the diagram, the approximate abundance of oxygen atoms in the galaxy is __________. -
Answers 1/1000 that of hydrogen
According to the diagram, what is the most abundant element with an atomic number greater than or
equal to 20? - Answers iron
Based on the diagram, which of the following statements best describes the observed pattern of
abundances for elements with an atomic number between 6 and 20? - Answers There is a general
trend of decreasing abundance with increasing atomic number, but elements with even atomic
numbers tend to be more abundant than those with odd atomic numbers.
According to current understanding, the two most abundant elements in the universe were made
__________. - Answers in the Big Bang
In Part D, you saw that elements with even atomic numbers tend to be more abundant than
neighboring elements with odd atomic numbers. What nuclear process explains why this is the case? -
Answers Starting from carbon (atomic number is 6), the most common nuclear reactions involve the
fusion of an additional helium nucleus.
The observational data for the element abundances agree quite well with what we expect based on
our current understanding of nuclear fusion and stellar evolution. But imagine the data had turned
out to be different. Which of the following differences, if it had actually been observed, would have
Shown below here is the track on the H-R diagram of a star like the Sun. At Point A the star is -
Answers fusing hydrogen in a shell around a collapsing core.
Submit
From the same H-R diagram above, at Point B, the star is - Answers fusing helium in its core and
hydrogen in a shell.
From the same H-R diagram above, at Point C, the star is - Answers has a stable, inert carbon core
and essentially no hydrogen or helium.
A supernova occurs when - Answers a massive star fuses through successively heavier elements until
it has an iron core, which will not release energy from fusion.
Consider a young globular star cluster where all the cluster stars formed at about the same time. If
you were to observe this star cluster over several billion years, you would see - Answers many
supernovae early on, and then no more.
Why are red giant stars rare compared to main-sequence stars? - Answers The amount of time a red
giant lasts is small compared to the lifespan of a main-sequence star.
Why doesn't a high-mass star fuse its iron into heavier elements, like uranium? - Answers No mass-
energy is released due to the fusion of iron.
In the dying stages of our Sun, it will fuse helium into carbon. After that, what will occur? - Answers
The core contracts, but the carbon never fuses.
Listed following are characteristics that describe either high-mass or low-mass stars. Match these
characteristics to the appropriate category. - Answers High-mass stars:
late in-life fuse carbon into heavier elements
have higher fusion rate during main sequence life
end life as supernova
Low-mass stars:
the Sun is an example
have longer lifetimes
final corpse is a white dwarf
end life as a planetary nebula
Provided following are various stages during the life of a high-mass star. Rank the stages based on
when they occur, from first to last. - Answers contracting cloud of gas and dust, protostar, main
sequence star, red supergiant, supernova, neutron star
Provided following are various elements that can be produced during fusion in the core of a high mass
main sequence star. Rank these elements based on when they are produced, from first to last. -
Answers helium, carbon, oxygen, iron
The diagram indicates that the third most abundant element in the Milky Way Galaxy is _____. -
Answers oxygen
According to the diagram, the approximate abundance of oxygen atoms in the galaxy is __________. -
Answers 1/1000 that of hydrogen
According to the diagram, what is the most abundant element with an atomic number greater than or
equal to 20? - Answers iron
Based on the diagram, which of the following statements best describes the observed pattern of
abundances for elements with an atomic number between 6 and 20? - Answers There is a general
trend of decreasing abundance with increasing atomic number, but elements with even atomic
numbers tend to be more abundant than those with odd atomic numbers.
According to current understanding, the two most abundant elements in the universe were made
__________. - Answers in the Big Bang
In Part D, you saw that elements with even atomic numbers tend to be more abundant than
neighboring elements with odd atomic numbers. What nuclear process explains why this is the case? -
Answers Starting from carbon (atomic number is 6), the most common nuclear reactions involve the
fusion of an additional helium nucleus.
The observational data for the element abundances agree quite well with what we expect based on
our current understanding of nuclear fusion and stellar evolution. But imagine the data had turned
out to be different. Which of the following differences, if it had actually been observed, would have
