Question 1

The helium fusion process works by fusing two helium nuclei into one beryllium nucleus.

Accepted Answer

A) True 
 B)False

Question 2

Which of the following types of data provide evidence that helps us understand the life tracks of low- mass stars?

Accepted Answer

A)  spacecraft observations of the Sun
B)  H- R diagrams of open clusters
C)  observing a low- mass star over many years
D)  H- R diagrams of globular clusters

Question 3

After a supernova event occurring in a high- mass star, what is left behind?

Accepted Answer

A)  always a black hole
B)  always a neutron star
C)  always a white dwarf
D)  either a white dwarf or a neutron star
E)  either a neutron star or a black hole

Question 4

Stars spend about 90% of their lifetime on the main sequence.

Accepted Answer

A) True 
 B)False

Question 5

Where would a brown dwarf be located on an H- R diagram?

Accepted Answer

A)  in the lower left corner of the H- R diagram
B)  below and to the right of the lowest part of the main sequence
C)  above and to the left of the highest part of the main sequence
D)  in the upper right corner of the H- R diagram

Question 6

Most interstellar clouds remain stable in size because the force of gravity is opposed by within the cloud.

Accepted Answer

A)  thermal pressure
B)  stellar winds
C)  radiation pressure
D)  degeneracy pressure

Question 7

Which two energy sources can help a star maintain its internal thermal pressure?

Accepted Answer

A)  nuclear fusion and gravitational contraction
B)  nuclear fusion and chemical reactions
C)  nuclear fission and gravitational contraction
D)  nuclear fusion and nuclear fission
E)  chemical reactions and gravitational contraction

Question 8

What happens when a main- sequence star exhausts its core hydrogen fuel supply?

Accepted Answer

A)  The star becomes a neutron star.
B)  The core shrinks while the rest of the star expands.
C)  The entire star shrinks in size.
D)  The core immediately begins to fuse its helium into carbon.

Question 9

Stars with high masses live longer than stars with lower masses.

Accepted Answer

A) True 
 B)False

Question 10

What does the CNO cycle and the hydrogen proton- proton cycle have in common? Choose the best answer to the question.

Accepted Answer

A)  They both are ways to fuse hydrogen nuclei to make helium.
B)  They both trigger at the same temperature.
C)  They are both nuclear reactions; the CNO cycle makes carbon, nitrogen, and oxygen, and the proton cycle makes helium.
D)  They are both cycles in star lives.

Question 11

At approximately what temperature can helium fusion occur?

Accepted Answer

A)  100,000 K
B)  100 billion K
C)  1 million K
D)  100 million K
E)  10 million K

Question 12

What kind of gas cloud is most likely to give birth to stars?

Accepted Answer

A)  a cold, low- density gas cloud
B)  a cold, dense gas cloud
C)  a hot, low- density gas cloud
D)  a hot, dense gas cloud

Question 13

The main source of energy for a star as it grows in size to become a red giant is _ _.

Accepted Answer

A)  hydrogen fusion in a shell surrounding the central core
B)  hydrogen fusion in the central core
C)  gravitational contraction
D)  helium fusion in the central core

Question 14

Photographs of many young stars show long jets of material apparently being ejected from their poles.

Accepted Answer

A) True 
 B)False

Question 15

The most massive stars generate energy at the end of their lives by fusing iron in their cores.

Accepted Answer

A) True 
 B)False

Question 16

All stars that become supernovae will leave behind a neutron star.

Accepted Answer

A) True 
 B)False

Question 17

Which process is required to allow a gravitationally- collapsing gas cloud to continue to collapse?

Accepted Answer

A)  The cloud must collide with other clouds.
B)  The cloud must radiate much of its thermal energy.
C)  The cloud must trap most of its thermal energy.
D)  New dust particles must continually be made in the cloud.

Question 18

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. During which stage does the star have an inert (non- burning) helium core?

Accepted Answer

A)  iii
B)  vi
C)  viii
D)  iv
E)  vii

Question 19

Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusion or fission?

Accepted Answer

A)  oxygen
B)  iron
C)  silicon
D)  hydrogen

Question 20

The figure above shows the abundance of elements in the galaxy relative to hydrogen. Why does iron have a higher abundance than nearby elements?

Accepted Answer

A)  It has a higher density than other elements, and thus becomes locked away in dust.
B)  It is the end product of core fusion in massive stars, and can only be destroyed in rare supernova fusion reactions.
C)  It does not; this apparent higher abundance is due to iron's many spectral lines making it easier to find.

Exam 13: Star Stuff

All stars that become supernovae will leave behind a neutron star.

Correct AnswerverifiedShow Answer

What happens when a main- sequence star exhausts its core hydrogen fuel supply?

Correct AnswerverifiedShow Answer

Which of the following types of data provide evidence that helps us understand the life tracks of low- mass stars?

Correct AnswerverifiedShow Answer

What kind of gas cloud is most likely to give birth to stars?

Correct AnswerverifiedShow Answer

The main source of energy for a star as it grows in size to become a red giant is _ _.

Correct AnswerverifiedShow Answer

Which two energy sources can help a star maintain its internal thermal pressure?

Correct AnswerverifiedShow Answer

What does the CNO cycle and the hydrogen proton- proton cycle have in common? Choose the best answer to the question.

Correct AnswerverifiedShow Answer

Where would a brown dwarf be located on an H- R diagram?

Correct AnswerverifiedShow Answer

Stars with high masses live longer than stars with lower masses.

Correct AnswerverifiedShow Answer

After a supernova event occurring in a high- mass star, what is left behind?

Correct AnswerverifiedShow Answer

Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusion or fission?

Correct AnswerverifiedShow Answer

The figure above shows the abundance of elements in the galaxy relative to hydrogen. Why does iron have a higher abundance than nearby elements?

Correct AnswerverifiedShow Answer

Photographs of many young stars show long jets of material apparently being ejected from their poles.

Correct AnswerverifiedShow Answer

Which process is required to allow a gravitationally- collapsing gas cloud to continue to collapse?

Correct AnswerverifiedShow Answer

Stars spend about 90% of their lifetime on the main sequence.

Correct AnswerverifiedShow Answer

At approximately what temperature can helium fusion occur?

Correct AnswerverifiedShow Answer

The helium fusion process works by fusing two helium nuclei into one beryllium nucleus.

Correct AnswerverifiedShow Answer

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. During which stage does the star have an inert (non- burning) helium core?

Correct AnswerverifiedShow Answer

The most massive stars generate energy at the end of their lives by fusing iron in their cores.

Correct AnswerverifiedShow Answer

Most interstellar clouds remain stable in size because the force of gravity is opposed by within the cloud.

Correct AnswerverifiedShow Answer

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