Deck 6: Earth

Question 1

A rock has a density of 2 g/cm³. If another rock has twice as much mass but the same volume, its density must be _____ g/cm³.

A) 0.5
B) 2
C) 4
D) 8

Answer 1

0.5

Question 2

A spherical rock has a density of 3 g/cm ³. If another rock has the same mass but is twice as wide, its density must be _____ g/cm ³.

A) 3/8
B) 3/4
C) 3/2
D) 6

Answer 2

3/8

Question 3

The radius of Earth is

A) larger at the poles.
B) larger at the equator.
C) the same everywhere.
D) not known.

Answer 3

larger at the equator.

Question 4

Density is calculated as

A) mass times volume.
B) mass divided by volume.
C) volume divided by mass.
D) mass times gravity.

Question 5

The average density of Earth is __________.

A) about 5.5 g/cm³
B) about 5.5 cm³/g
C) about 1 g/cm³
D) about 1 cm³/g

Question 6

The typical density for a rock found on the surface of Earth is ________ the average density of Earth overall.

A) greater than
B) less than
C) about equal to

Question 7

Why are Earth and other planets spherical while smaller bodies such as most asteroids are not?

A) Asteroids were never molten, and so never underwent differentiation.
B) The larger mass of a planet produces enough gravity to pull it into a round shape.
C) The atmosphere of a planet is heavy enough to push the planet into a round shape.
D) Earth and other planets formed from planetesimals pulled together by gravity into circular orbits.
E) It is the nature of massive objects to pull themselves into spherical shapes.

Question 8

What is the geometric shape of Earth?

A) a perfect sphere
B) an oblate spheroid
C) a prolate ellipsoid
D) an annular toroid
E) flat

Question 9

Rocks that include silicon and oxygen as major components are called ____.

A) silicons
B) silicates
C) dioxides
D) di-silicons
E) silicides

Question 10

What is a silicate?

A) rocks that include silicon and oxygen as major components
B) low-density rocks frequently found on the surface of Earth
C) quartz
D) silicon dioxide
E) All of these choices are correct.

Question 11

What is olivine?

A) silicate rock that makes up much of the mantle
B) silicate rock found mostly on the surface of Earth
C) iron-based non-silicate rock that is green in color
D) lithium dioxide
E) None of these choices are correct.

Question 12

The Moon has an average density of 3.3 g/cm³. From this number, what can we infer about the composition of the Moon?

A) Its composition is mostly metals and water ice.
B) Its composition is mostly silicates, with some iron.
C) Its composition is exactly the same as Earth's.
D) Its composition is entirely silicates.
E) None of these choices are correct.

Question 13

What are the most common elements composing Earth?

A) hydrogen and helium
B) carbon and nitrogen
C) oxygen and silicon
D) uranium and plutonium

Question 14

The outer core of Earth extends out to a little over halfway to the surface of Earth. The volume of the core is therefore about _________ the volume of Earth.

A) 1/64
B) 1/8
C) 1/4
D) 1/2

Question 15

From the center outward, the correct order of the zones of Earth is

A) solid core, mantle, liquid core, crust, atmosphere.
B) liquid core, solid core, crust, mantle, atmosphere.
C) solid core, liquid core, mantle, crust, atmosphere.
D) liquid core, solid core, mantle, crust, atmosphere.

Question 16

The most abundant element in Earth's core is ___________.

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

Question 17

After an earthquake, an S-type seismic wave travels with a velocity of about 10 km/s and reaches another part of Earth in about 10 minutes. How far has the S-type wave traveled?

A) 6,000 km
B) 1,000 km
C) 600 km
D) 100 km
E) 60 km

Question 18

The interior layer just below the crust of Earth is called the _______.

A) inner core
B) outer core
C) mantle
D) troposphere

Question 19

The hotter inner core of Earth is _______ and the relatively cooler outer core is ______.

A) solid; also solid
B) liquid; also liquid
C) liquid; solid
D) solid; liquid

Question 20

Why is Earth's inner core solid?

A) due to extremely high temperature
B) due to the tremendous pressure of overlying material
C) due to the spinning of earth
D) Earth formed by liquid material piling on top of a solid sphere.

Question 21

The ___-type seismic waves can travel through liquids and solids. The ___-type seismic waves can travel through solids only.

A) S; P
B) S; S
C) P; S
D) P; P

Question 22

Scientists refer to Earth as a differentiated planet because __________.

A) the temperature in the core is higher than the temperature on the surface
B) the material in the interior of Earth is arranged by density
C) iron is more dense than silicate material
D) Earth's structure is different from the other planets

Question 23

Earthquakes generate ____ that scientists can use to deduce the internal structure of Earth.

A) seismic waves
B) weather patterns
C) magnetic fields
D) electromagnetic waves
E) lava flows

Question 24

How do earthquake-generated waves help scientists deduce the internal structure of Earth?

A) Primary waves are detected at a seismometer when they pass through solid or liquid materials.
B) Secondary waves are detected at a seismometer when they pass through solid materials.
C) The path of waves bends as they travel through material of different density.
D) Earthquake-generated waves can be detected and studied anywhere in the world.
E) All of these choices are correct.

Question 25

The uppermost layer of Earth's structure is called the ____.

A) core
B) mantle
C) crust
D) surface
E) silicate

Question 26

The uppermost layer of Earth's structure is composed of mostly ____.

A) silicates
B) olivines
C) metals
D) oxygen and nitrogen
E) All of these choices are correct.

Question 27

How has Earth's interior remained warm over its geological history?

A) radioactive decay
B) leftover heat from formation
C) Earth's proximity to the Sun
D) tidal stresses from the Moon
E) the greenhouse effect

Question 28

Why will a smaller body (the Moon, for example) cool much faster than a larger body like Earth?

A) A smaller body has a larger surface area for heat to escape through, relative to its volume.
B) A smaller body will have a smaller proportion of radioactive elements.
C) A smaller body is less likely to have an atmosphere than a larger body.
D) A smaller body will have a smaller iron core, which holds heat better than rock.

Question 29

How does the differentiation process generate heat?

A) As dense material sinks through less dense rock, it generates heat through friction.
B) As low-density rock rises to the surface, it carries heat from the interior of the planet.
C) Heat is generated by the constant bombardment of the planet by planetesimals.
D) Iron and nickel accumulating at the center of the planet concentrate the planet's heat.

Question 30

How do we know Earth has a liquid core?

A) Both S and P waves pass through it.
B) S waves pass through it, but P waves do not.
C) P waves pass through it, but S waves do not.
D) Because we have used X-rays to probe it.

Question 31

Why is the inner core solid even though it is hotter than the outer liquid core?

A) This is not unusual: hotter things tend to be more solid.
B) The great pressure at Earth's center forces the atoms in the core together, causing it to solidify.
C) Radioactivity cause liquid materials to become solid.
D) The dynamo effect causes ions in Earth's interior to become solid.

Question 32

Why do we believe Earth has an iron core?

A) Samples from deep holes are iron rich.
B) X-ray cameras show a dark, impenetrable mass at the planet's center.
C) The properties of seismic waves match those expected of a region of iron.
D) Astronomers have seen asteroid impacts sinking into the deep interior.
E) Volcanoes erupt nearly pure iron.

Question 33

About how hot is the core of Earth?

A) 15 million K
B) 15,000 K
C) 6,500 K
D) 300 K

Question 34

The interior of Earth is very hot because of ________________.

A) fusion reactions
B) the radioactive decay of elements
C) oxidation
D) internal combustion

Question 35

What might explain how the core formed?

A) asteroids hitting and penetrating
B) iron sinking to the core as the bulk of Earth melted
C) the magnetic field pulling it inward
D) Earthquakes shake the planet and the iron gradually "sifts" downward
E) The silicon of the crust decays into iron at high temperatures

Question 36

Why is the core hot?

A) from the steady decay of radioactive atoms in the rock
B) from heat left over from the planet's birth
C) The high pressure in the core drives the temperature higher.
D) from both the decay of radioactive atoms and the leftover heat
E) None of these choices are correct.

Question 37

Carbon-13 is a radioactive isotope. About half of a sample decays in 6,000 years. After how long would only 1/8 of the original carbon 13 be left?

A) 6,000 years
B) 12,000 years
C) 18,000 years
D) 24,000 years
E) 30,000 years

Question 38

How is the age of a rock determined?

A) by determining the ratio of argon to potassium
B) by counting the number of circles just like the circles on the trunk of a tree
C) by measuring the temperature of the rock
D) by measuring the amount of calcium it contains

Question 39

Suppose that we have a sample of 20 atoms of radioactive potassium which decays by half every 1.3 billion years into calcium and argon at ratios of 9:1, respectively. How many atoms of calcium do you expect to find in this sample after 1.3 billion years?

A) 18
B) 1
C) 9
D) 2

Question 40

How is the age of Earth measured?

A) by counting tree rings
B) by analyzing the strength of Earth's magnetic field
C) by studying the ratios of radioactive materials in rocks
D) by measuring the amount of heat the planet emits into space

Question 41

_________ and _________ are common in regions where subduction occurs.

A) Rifts; polarity shifts
B) Volcanoes; plate spreading
C) Auroras; the Coriolis Effect
D) Mountains; earthquakes

Question 42

The process in which two tectonic plates meet and one slips beneath another is called _____.

A) convection
B) pangea
C) subduction
D) rifting

Question 43

How fast are Earth's plates moving due to tectonic motion?

A) a few kilometers per year
B) a meters per year
C) a few centimeters per year
D) a few centimeters per century

Question 44

The process by which material heated from below rises and cooled material sinks is called ______.

A) conduction
B) convection
C) radiation
D) differentiation
E) subduction

Question 45

Within the mantle, how is heat transported outward away from the core?

A) conduction
B) convection
C) radiation
D) differentiation
E) subduction

Question 46

The circular flow of rising hot material and sinking cool material is responsible for what phenomena on and in Earth?

A) rifting
B) subduction
C) volcanic eruptions
D) earthquakes
E) All of these choices are correct.

Question 47

____ is the process in which hot mantle material drags sections of Earth's crust apart, creating new crust.

A) Subduction
B) Rifting
C) Drifting
D) Conduction
E) Ridging

Question 48

Where do we find the youngest parts of Earth's crust?

A) subduction zones
B) ridges on the ocean floor
C) at the bases of mountains
D) at the tops of mountains
E) None of these choices are correct.

Question 49

The shifting of large blocks of Earth's surface is usually referred to today as what?

A) the dynamo effect
B) continental drift
C) the Coriolis effect
D) plate tectonics

Question 50

What is happening when two plates are smashing into one another?

A) Subduction causes mountains to be built up; earthquakes and volcanoes may also occur.
B) Rifting causes mountains to be built up; earthquakes and volcanoes may also occur.
C) Precession causes mountains to be built up; earthquakes and volcanoes may also occur.
D) nothing

Question 51

Van Allen Belts exist in Earth's ___________.

A) troposphere
B) core
C) mantle
D) magnetosphere

Question 52

The ______ are two doughnut-shaped rings of charged particles trapped by Earth's magnetic field.

A) Aurora Borealis and the Aurora Australis
B) Van Allen Radiation Belts
C) jet streams
D) convection cells

Question 53

What do we mean when we say that a magnetic field has polarity?

A) A magnetic field has a north and south "poles" or directions.
B) A magnetic field is able to flip its poles over a long period of time.
C) A planetary magnetic field is aligned with the geographic poles of the planet.
D) A planetary magnetic field is strongest at the poles of the planet.
E) None of these choices are correct.

Question 54

What evidence do we have that Earth's magnetic field reverses its polarity every 250,000 years?

A) historical documents from ancient Egypt and other civilizations
B) The direction of the magnetic field is "frozen" into new crust as it cools.
C) Core samples from Antarctica show a regular change in polarity.
D) Earth's magnetic field strength and direction change constantly.
E) All of these choices are correct.

Question 55

What is the dynamo model of Earth's magnetic field?

A) Earth's magnetic field is maintained by convection in the interior of the planet, as well as its rotation.
B) Electric currents in the atmosphere (aurora) generate Earth's magnetic field.
C) Currents in Earth's oceans maintain the planet's magnetic field.
D) Earth's magnetic field changes too rapidly for it to be generated in Earth's interior.
E) None of these choices are correct.

Question 56

Why does the Moon not have a magnetic field?

A) It rotates very slowly and has a cold interior.
B) Any field the Moon could generate is overwhelmed by Earth's field.
C) The Moon lacks an atmosphere.
D) Only planets can have magnetic fields.
E) The Moon's magnetic field was destroyed by bombardment by planetesimals.

Question 57

Currents in Earth's molten iron core create the planet's magnetic field. These currents are probably caused by

A) rotational motion and radioactivity.
B) rotational motion and convection.
C) radioactivity and convection.
D) rifting and subduction.

Question 58

What causes auroras?

A) sunlight reflected off meteor dust high in the atmosphere
B) micro meteorites burning up as they sweep along Earth's magnetic field
C) particles from the Sun colliding with and exciting atoms in our upper atmosphere
D) fluorescence by upper atmospheric hydrogen atoms
E) waves in the magnetic field creating an upper atmospheric laser-like effect

Question 59

Analysis of volcanic emissions suggests that eruptions could be the source of all but which of the following gases in our atmosphere?

A) oxygen
B) nitrogen
C) water
D) carbon dioxide

Question 60

Ozone

A) is an element.
B) is a molecule consisting of two oxygen atoms and a hydrogen atom.
C) is a molecule consisting of three oxygen atoms.
D) is a molecule consisting of two oxygen atoms and a nitrogen atom.

Question 61

The composition of Earth's atmosphere today is about 78% _____, 21% _____, and about 1% __________, with trace amounts of other gases.

A) oxygen; nitrogen; water vapor
B) nitrogen; carbon dioxide; oxygen
C) oxygen; carbon dioxide; nitrogen
D) nitrogen; oxygen; argon
E) nitrogen; oxygen; carbon dioxide

Question 62

The majority of Earth's atmosphere is found within which atmospheric layer?

A) troposphere
B) stratosphere
C) ozone layer
D) van Allen Belts
E) ionosphere

Question 63

What is the troposphere?

A) the layer of the atmosphere where the weather we experience is located
B) the layer of the atmosphere containing the aurora
C) the layer of the atmosphere containing the ozone layer
D) the uppermost layer of the atmosphere
E) None of these choices are correct.

Question 64

What is the stratosphere?

A) the layer of the atmosphere where the weather we experience is located
B) the layer of the atmosphere containing the aurora
C) the layer of the atmosphere containing the ozone layer
D) the uppermost layer of the atmosphere
E) None of these choices are correct.

Question 65

Why is the Moon's average surface temperature so much lower than Earth's?

A) The Moon is much smaller than Earth and cooled more quickly.
B) The Moon has no magnetic field to prevent infrared radiation from escaping.
C) The Moon has no atmosphere to help retain heat at its surface.
D) The Moon's rotation rate is much slower than Earth's.
E) The Moon reflects more of the Sun's energy than Earth.

Question 66

What is the origin of Earth's atmosphere?

A) Gases were brought to Earth by cometary impacts.
B) Gases were released into the atmosphere by volcanic eruptions.
C) Gases were released when planetesimals impacted Earth's surface and melted it.
D) All of these choices are correct.

Question 67

The early atmosphere of Earth had more methane and ammonia than what is present today. Where did these gases go?

A) Sunlight broke methane and ammonia apart and the hydrogen escaped to space.
B) Methane and ammonia dissolved in Earth's oceans.
C) Plant life converted methane and ammonia to nitrogen and carbon through photosynthesis.
D) Cometary and planetesimal impacts provided enough energy for these gases to escape to space.

Question 68

Which gases are added to Earth's atmosphere by volcanic eruptions?

A) carbon dioxide, water vapor, and nitrogen
B) ammonia, methane, and oxygen
C) carbon dioxide, ozone, and methane
D) nitrogen, oxygen, and ammonia

Question 69

The early atmosphere of Earth had much less oxygen than today. How has Earth's oxygen abundance increased over Earth's history?

A) Plant life generated oxygen through photosynthesis.
B) Volcanic eruptions release large amounts of oxygen.
C) Ultraviolet light breaks up ozone into oxygen.
D) Cometary impacts over Earth's history have contributed oxygen to the atmosphere.
E) None of these choices are correct.

Question 70

What causes the greenhouse effect?

A) Water vapor and carbon dioxide absorb visible sunlight and warms the atmosphere.
B) Ozone absorbs solar ultraviolet radiation and warms the atmosphere.
C) Oxygen and nitrogen scatter sunlight which heats the atmosphere by its frictional passage.
D) Water vapor and carbon dioxide absorb infrared radiation from the ground and reradiate the heat toward the surface.
E) Fluorocarbons absorb infrared radiation from the Sun and heat the surface.

Question 71

What does the Greenhouse Effect cause?

A) It shields us from the Sun's ultraviolet rays.
B) It causes Earth's surface and atmosphere to be warmer than they would be otherwise.
C) It is the main source of Earth's oxygen.
D) It protects the surface of Earth from cosmic rays.

Question 72

What are the main constituents of Earth's atmosphere?

A) carbon dioxide and water vapor
B) hydrogen and helium
C) methane and ozone
D) nitrogen and oxygen

Question 73

The ozone layer protects us from

A) infrared radiation.
B) ultraviolet radiation.
C) gamma rays.
D) cosmic rays.

Question 74

In about 14,000 AD, the North Pole of Earth will point at star ________.

A) Polaris
B) Antares
C) Vega
D) Thuban

Question 75

The deflection of air and ocean currents from their original direction of motion due to the rotation of Earth is called ____.

A) precession
B) the Coriolis Effect
C) differentiation
D) circulation
E) revolution

Question 76

A pocket of air moving south in the Northern Hemisphere will be deflected ____ by the rotation of Earth?

A) to the west
B) to the east
C) upward to a higher altitude
D) downward toward the surface
E) to the south

Question 77

A pocket of air moving north in the Northern Hemisphere will be deflected ____ by the rotation of Earth.

A) to the west
B) to the east
C) upward to a higher altitude
D) downward toward the surface
E) to the south

Question 78

Why isn't Earth a perfect sphere?

A) Rotation causes the equator to bulge out.
B) Rotation causes the poles to bulge out.
C) Earth's magnetic field causes the equator to bulge out.
D) Earth is perfectly round.

Question 79

The wobble of Earth's rotational axis resulting in a change in location of the north celestial pole is called ____.

A) precession
B) the Coriolis Effect
C) revolution
D) deflection
E) differentiation

Question 80

What causes the slow wobble of Earth's rotational axis?

A) The Sun and the Moon exert unbalanced gravitational forces on Earth's equatorial bulge.
B) Continents are concentrated in the Northern Hemisphere, which creates an unbalanced rotation of Earth.
C) The Moon exerts a gravitational force on Earth's tidal bulges, creating a wobble.
D) The accumulation of ice at the poles during ice ages creates an unbalanced rotation of Earth.