1. Seismic waves are used to probe Earth's deep interior and determine its structure. 2. The typical density of rocks in Earth's crust is 3.0 grams per cubic centimeter. 3. The density of rocks in Earth's mantle ranges from 2.7 to 5.2 grams per cubic centimeter.

1. Assignment Name: Fraknoi/Morrison/Wolff, Voyages Through the Universe 3e, Ch 7
Total Possible: 20.0Time Spent: 00:18:24
How do we probe the deep interior of Earth to determine its interior structure?
a. By drilling deep wells down to the center.
b. With radar pulses from the largest radio telescope.
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c. By monitoring seismic waves.
d. Through analysis of volcanic lava coming up from Earth's core.
e. By sending high-energy gamma ray pulses through Earth.
status: correct (1.0)
correct: c
your answer: c
feedback: Correct.
What is the typical density of rocks from Earth's crust?
a. 1.0 grams per cubic centimeter
b. 2.5 grams per cubic centimeter
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c. 3.0 grams per cubic centimeter
d. 5.5 grams per cubic centimeter
e. 7.9 grams per cubic centimeter
status: correct (1.0)
correct: c
your answer: c
feedback: Correct.
What is the density of the rocks of Earth's mantle?
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a. 0.9 grams per cubic centimeter

2. b. 1.0 grams per cubic centimeter
c. 2.7 to 3.3 grams per cubic centimeter
d. 3.5 to 5.2 grams per cubic centimeter
e. 7.9 to 14 grams per cubic centimeter
status: correct (1.0)
correct: d
your answer: d
feedback: Correct.
Why do mantle rocks have a higher density than crust rocks?
a. As Earth formed the higher-density pieces came together first.
b. When Earth was molten the lower-density materials quot;floatedquot; to the surface.
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c. A large impact shattered the surface rocks and lowered their density.
d. Sunlight warms and expands the surface rocks, giving them a lower density.
Atmospheric gases are absorbed by surface rocks, giving them a lower
e. density.
status: correct (1.0)
correct: b
your answer: b
feedback: Correct.
Which of the following is the most accurate description of Earth's metallic core?
a. Earth's core is solid.
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b. Earth's core is liquid.
c. Earth's outer core is solid and the inner core is liquid.

3. d. Earth's outer core is liquid and the inner core is solid.
Earth's outer core is solid, the intermediate core is liquid, and inner core is
e. solid.
status: correct (1.0)
correct: d
your answer: d
feedback: Correct.
What is the most likely source of Earth's magnetic field?
a. The solid iron core of Earth is a permanent magnet.
b. A current-carrying coil of wire is wrapped around Earth's core.
6 A circulating electric current flows through the salty water of Earth's
c. oceans.
Charged particles of the solar wind flow into one pole of Earth and out the
d. other pole.
Moving material in the liquid outer core sets up a circulating electric
e. current.
status: correct (1.0)
correct: e
your answer: e
feedback: Correct.
Which description best describes the extent of Earth's magnetosphere?
Earth's magnetosphere extends out about 10 Earth radii on the Sunward
a. side, and about 60 Earth radii on the side away from the Sun.
Earth's magnetosphere extends out about 60 Earth radii on the Sunward
b. side, and about 10 Earth radii on the side away from the Sun.
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c. Earth's magnetosphere extends out to 3 Earth radii in all directions.
d. Earth's magnetosphere extends out to 6.5 Earth radii in all directions.
e. Earth's magnetosphere extends out about 10 Earth radii in all directions.

4. status: correct (1.0)
correct: a
your answer: a
feedback: Correct.
Which type of rock has solidified from a molten state?
a. igneous
b. sedimentary
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c. metamorphic
d. primitive
e. acid
status: correct (1.0)
correct: a
your answer: a
feedback: Correct.
Where might you find primitive rocks?
a. On Earth's moon.
b. On a small asteroid.
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c. In Earth's crust.
d. On Mars.
e. On Mercury.
status: correct (1.0)
correct: b
your answer: b
feedback: Correct.

5. What is the typical speed of a moving tectonic plate?
a. About 1 kilometer per hour.
b. A few meters per hour.
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c. A few kilometers per month.
d. A few meters per year.
e. A few centimeters per year.
status: correct (1.0)
correct: e
your answer: e
feedback: Correct.
What powers plate tectonics?
a. Tidal forces due to the Moon.
b. Tidal forces due to the Sun.
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c. Ocean currents due to seasonal solar heating.
d. Convective cells in Earth's mantle.
e. Differential rotation of Earth's interior.
status: correct (1.0)
correct: d
your answer: d
feedback: Correct.
What is convection?
a. The upward flow of warm material and downward flow of cooler material.
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b. The transfer of energy by electromagnetic radiation.

6. c. The transfer of energy through contact of adjacent material.
The transfer of energy from a low-temperature object to a high-
d. temperature object.
e. Being found guilty of a crime.
status: correct (1.0)
correct: a
your answer: a
feedback: Correct.
What happens at a subduction zone?
Rising magma fills the gap between diverging oceanic plates to form new
a. oceanic crust.
b. An oceanic plate slides beneath a continental plate.
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c. Two continental plates collide.
d. One plate slides alongside of another plate.
e. The impacting body is vaporized.
status: correct (1.0)
correct: b
your answer: b
feedback: Incorrect. Correct.
Along which type of plate boundary has the Alps mountain range of southern
Europe formed?
a. A rift zone.
14 b. A subduction zone.
c. Two plates sliding past one another (a strike-slip boundary).
d. The collision of two continental plates.

7. e. A divergent zone.
status: correct (1.0)
correct: d
your answer: d
feedback: Correct.
How did the volcanic Hawaiian Island chain form?
a. From the impact of a large asteroid.
b. Due to a hot spot under the moving Pacific Plate.
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c. At the boundary between two colliding oceanic plates.
d. Along a subduction zone.
e. Along a rift zone.
status: correct (1.0)
correct: b
your answer: b
feedback: Correct.
The ozone layer high in Earth's atmosphere absorbs sunlight of which band of
wavelengths:
a. Ultraviolet
b. Infrared
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c. Visible
d. Microwave
e. Radio
status: correct (1.0)
correct: a

8. your answer: a
feedback: Correct.
How does the total mass of liquid water on Earth compare to the total mass of the
atmosphere?
a. Both have about the same mass.
b. The atmosphere has about twice as much mass.
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c. The atmosphere has about 300 times as much mass.
d. Water has about twice as much mass.
e. Water has about 300 times as much mass.
status: correct (1.0)
correct: e
your answer: e
feedback: Correct.
Which greenhouse gas is increasing by about 0.5% per year in Earth's
atmosphere?
a. water vapor
b. nitrogen
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c. carbon dioxide
d. oxygen
e. argon
status: correct (1.0)
correct: c
your answer: c
feedback: Correct.

9. Which of the following is evidence supporting an extraterrestrial impact as the
cause of the extinction of the dinosaurs (and many other species) 65 million years
ago?
a. Most dinosaur fossils are found buried in rock.
A 65-million-year-old, 200-km-diameter buried crater located in southern
b. Mexico.
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Iridium enriched sediments deposited all over the world 65 million years
c. ago.
d. All of the above.
e. Choices b & c above.
status: correct (1.0)
correct: e
your answer: e
feedback: Correct.
What is the estimated number of Earth-crossing asteroids that are big enough to
kill hundreds of millions of people if they collide with Earth?
a. 10
b. 50
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c. 120
d. 330
e. 1100
status: correct (1.0)
correct: e
your answer: e
feedback: Correct.