Geology 109 Exam 1 Questions and Answers Verified
100% Correct|
Which of the following are correct about red giant stars? (select all that apply)
-These are very young stars that are cool because fusion has not started in them.
-They form as a star expands and the surface cools.
-They are among the stars with the hottest surfaces.
-They evolve from medium-sized stars.
-They evolve from large stars.
-Heavy elements like uranium and thorium form in their interiors. - answers -They form as a
star expands and the surface cools. -They evolve from medium-sized stars.
Red giants form by expansion and cooling of the surface of a medium-sized star.
Put the following stages in the evolution of a medium-sized star in the correct time order,
placing the first stage on the top and the last stage on the bottom.
List of terms to organize:
-Prostar
-Planetary Nebula
-Main sequence Star
-Molecular Cloud
-Red Giant - answers molecular cloud --> protostar --> main sequence star --> red giant -->
planetary nebula
Medium stars condense into a protostar out of cosmic gas and dust. As the protostar gathers more
debris it becomes a main sequence star. Near the end of its life the star will grow into a red giant,
and finally the outer layers will be shed, creating a planetary nebula. Supernovas and black holes
only form from large stars.
Which kind of stars have the longest lifetimes (~10 billion years)?
-Medium-sized stars like our Sun.
-Large stars about 10 times larger than the Sun. - answers Medium-sized stars like our Sun
The larger the star, the faster the star uses its fuel.
A giant molecular cloud is best described by which statement?
,-It is a hot mass of ionized gas that cannot collapse to form a star.
-It is the ejected shell from a dying red giant star.
-It is a cool mass of gas and dust that can be light years across.
-It is a cloud of gas and dust violently ejected from a supernova explosion. - answers It is a cool
mass of gas and dust that can be light years across.
A molecular cloud is a grouping of cool gas and dust. Not to be confused with a planetary nebula
that forms from the death of a medium-sized star.
Which of the following is correct about the nebulas we see in the sky today? (select all that
apply)
-They formed during the "Big Bang."
-They are concentrations of interstellar gas and dust.
-Many are the birth grounds of stars.
-Some form when stars explode. - answers -They are concentrations of interstellar gas and dust.
-Many are the birth grounds of stars.
-Some form when stars explode.
The nebulas we see today are concentrations of gas and dust that give rise to new stars. Some of
these nebulas formed by supernovas.
A "star" that shines, but not as a result of nuclear reactions, is called a __________.
-T-Tauri star
-nebula
-protostar
-supernova
-planetismal - answers protostar
Protostars shine because of the heat produced by friction as debris collapses onto the forming
star. The T-tauri stage of a star begins with the onset of nuclear fusion. A nebula shines because
of surrounding stars and planetismals do not shine at all.
Condensation in the solar nebula and accretion of planets is thought to have occurred about how
many years ago?
-4,500 y
-4,500,000 y
,-450,000,000 y
-4,500,000,000 y - answers 4,500,000,000 y
Ages from meteorites suggest condensation occurred 4.5 billion years ago.
Most of the mass of the solar nebula resided in materials which __________.
-did not condense to form solids.
-condensed to form ice.
-condensed to form silicate materials.
-condensed to form metals. - answers did not condense to form solids
Most of the material in the Solar System (more than 99%) resides in the Sun and therefore, did
not condense to form any solids.
What were the most common solids that condensed from the solar nebular gases?
-They were silicates that lacked water.
-They were silicates that contained water.
-They consisted of carbonaceous material.
-They were made of iron.
-They were water ice. - answers They were water ice.
Water ice is the most common condensate in the Solar System. It may not be the most common
in the inner Solar System, but the asteroid belt and beyond contains a vast amount of water ice.
Examples of highly refractory materials are __________.
(hint: there's 3) - answers tungsten (W), osmium (Os), & zirconium (Zr)
Refractory elements are those that condense at high temperatures. Volatile elements condense at
low temperatures.
Which list is made of very volatile materials?
-helium (He), argon (Ar), ammonia (NH3), and methane (CH4)
-iron (Fe), nickel (Ni), and iron sulfide (FeS)
-tungsten (W), osmium (O), and zirconium (Zr)
-sodium (Na), potassium (K), and rubidium (Rb)—the alkalies - answers helium (He), argon
(Ar), ammonia (NH3), and methane (CH4)
, Helium, argon, methane, and ammonia are very volatile elements and only condense at
extremely cold temperatures.
Why are the inner planets depleted (poor) in volatile elements?
-Their constituents condensed at lower temperatures.
-Their constituents condensed at high temperatures.
-They formed from portions of the nebula depleted in these elements.
-They are not depleted in volatiles.
-Hydrogen is not stable inside the orbit of Mars. - answers Their constituents condensed at
higher temperatures.
The inner planets are enriched in refractory elements and depleted in volatile elements because
these planets formed near the Sun where it was too hot for volatile elements to condense, but was
not too hot for condensation of refractory elements.
Which of the following is involved in collisional accretion?
-The selective condensation of elements at different temperatures.
-The aggregation of planetismals when they impact one another.
-The hydrodynamic collapse of nebular gases.
-The gradual change of the gravitational constant. - answers The aggregation of planetismals
when they impact one another.
Collisional accretion is the gradual growing of material by colliding. This process does not have
to do with materials changing their state from gas to solid (condensation), a nebula becoming
smaller by collapse, or the gravitational constant changing (it is constant for a reason).
Which of the following are true about planetary accretion? (select all that apply)
-As these particles accreted, the planets became hot as kinetic energy was converted to thermal
energy.
-The planets grew larger and larger via low-speed collisions and sticking.
-The planets became internally differentiated to different degrees.
-The particles that accreted to form the planets were in orbit around the Sun. - answers -As these
particles accreted, the planets became hot as kinetic energy was converted to thermal energy.
-The planets grew larger and larger via repeated impact.
-The planets became internally differentiated to different degrees.
-The particles that accreted to form the planets were in orbit around the Sun.
100% Correct|
Which of the following are correct about red giant stars? (select all that apply)
-These are very young stars that are cool because fusion has not started in them.
-They form as a star expands and the surface cools.
-They are among the stars with the hottest surfaces.
-They evolve from medium-sized stars.
-They evolve from large stars.
-Heavy elements like uranium and thorium form in their interiors. - answers -They form as a
star expands and the surface cools. -They evolve from medium-sized stars.
Red giants form by expansion and cooling of the surface of a medium-sized star.
Put the following stages in the evolution of a medium-sized star in the correct time order,
placing the first stage on the top and the last stage on the bottom.
List of terms to organize:
-Prostar
-Planetary Nebula
-Main sequence Star
-Molecular Cloud
-Red Giant - answers molecular cloud --> protostar --> main sequence star --> red giant -->
planetary nebula
Medium stars condense into a protostar out of cosmic gas and dust. As the protostar gathers more
debris it becomes a main sequence star. Near the end of its life the star will grow into a red giant,
and finally the outer layers will be shed, creating a planetary nebula. Supernovas and black holes
only form from large stars.
Which kind of stars have the longest lifetimes (~10 billion years)?
-Medium-sized stars like our Sun.
-Large stars about 10 times larger than the Sun. - answers Medium-sized stars like our Sun
The larger the star, the faster the star uses its fuel.
A giant molecular cloud is best described by which statement?
,-It is a hot mass of ionized gas that cannot collapse to form a star.
-It is the ejected shell from a dying red giant star.
-It is a cool mass of gas and dust that can be light years across.
-It is a cloud of gas and dust violently ejected from a supernova explosion. - answers It is a cool
mass of gas and dust that can be light years across.
A molecular cloud is a grouping of cool gas and dust. Not to be confused with a planetary nebula
that forms from the death of a medium-sized star.
Which of the following is correct about the nebulas we see in the sky today? (select all that
apply)
-They formed during the "Big Bang."
-They are concentrations of interstellar gas and dust.
-Many are the birth grounds of stars.
-Some form when stars explode. - answers -They are concentrations of interstellar gas and dust.
-Many are the birth grounds of stars.
-Some form when stars explode.
The nebulas we see today are concentrations of gas and dust that give rise to new stars. Some of
these nebulas formed by supernovas.
A "star" that shines, but not as a result of nuclear reactions, is called a __________.
-T-Tauri star
-nebula
-protostar
-supernova
-planetismal - answers protostar
Protostars shine because of the heat produced by friction as debris collapses onto the forming
star. The T-tauri stage of a star begins with the onset of nuclear fusion. A nebula shines because
of surrounding stars and planetismals do not shine at all.
Condensation in the solar nebula and accretion of planets is thought to have occurred about how
many years ago?
-4,500 y
-4,500,000 y
,-450,000,000 y
-4,500,000,000 y - answers 4,500,000,000 y
Ages from meteorites suggest condensation occurred 4.5 billion years ago.
Most of the mass of the solar nebula resided in materials which __________.
-did not condense to form solids.
-condensed to form ice.
-condensed to form silicate materials.
-condensed to form metals. - answers did not condense to form solids
Most of the material in the Solar System (more than 99%) resides in the Sun and therefore, did
not condense to form any solids.
What were the most common solids that condensed from the solar nebular gases?
-They were silicates that lacked water.
-They were silicates that contained water.
-They consisted of carbonaceous material.
-They were made of iron.
-They were water ice. - answers They were water ice.
Water ice is the most common condensate in the Solar System. It may not be the most common
in the inner Solar System, but the asteroid belt and beyond contains a vast amount of water ice.
Examples of highly refractory materials are __________.
(hint: there's 3) - answers tungsten (W), osmium (Os), & zirconium (Zr)
Refractory elements are those that condense at high temperatures. Volatile elements condense at
low temperatures.
Which list is made of very volatile materials?
-helium (He), argon (Ar), ammonia (NH3), and methane (CH4)
-iron (Fe), nickel (Ni), and iron sulfide (FeS)
-tungsten (W), osmium (O), and zirconium (Zr)
-sodium (Na), potassium (K), and rubidium (Rb)—the alkalies - answers helium (He), argon
(Ar), ammonia (NH3), and methane (CH4)
, Helium, argon, methane, and ammonia are very volatile elements and only condense at
extremely cold temperatures.
Why are the inner planets depleted (poor) in volatile elements?
-Their constituents condensed at lower temperatures.
-Their constituents condensed at high temperatures.
-They formed from portions of the nebula depleted in these elements.
-They are not depleted in volatiles.
-Hydrogen is not stable inside the orbit of Mars. - answers Their constituents condensed at
higher temperatures.
The inner planets are enriched in refractory elements and depleted in volatile elements because
these planets formed near the Sun where it was too hot for volatile elements to condense, but was
not too hot for condensation of refractory elements.
Which of the following is involved in collisional accretion?
-The selective condensation of elements at different temperatures.
-The aggregation of planetismals when they impact one another.
-The hydrodynamic collapse of nebular gases.
-The gradual change of the gravitational constant. - answers The aggregation of planetismals
when they impact one another.
Collisional accretion is the gradual growing of material by colliding. This process does not have
to do with materials changing their state from gas to solid (condensation), a nebula becoming
smaller by collapse, or the gravitational constant changing (it is constant for a reason).
Which of the following are true about planetary accretion? (select all that apply)
-As these particles accreted, the planets became hot as kinetic energy was converted to thermal
energy.
-The planets grew larger and larger via low-speed collisions and sticking.
-The planets became internally differentiated to different degrees.
-The particles that accreted to form the planets were in orbit around the Sun. - answers -As these
particles accreted, the planets became hot as kinetic energy was converted to thermal energy.
-The planets grew larger and larger via repeated impact.
-The planets became internally differentiated to different degrees.
-The particles that accreted to form the planets were in orbit around the Sun.
