Chapter 6 Homework

Rank these materials based on their abundance in Earth's atmosphere, with the most common material at the top.

1. Nitrogen 2. Oxygen 3. Argon 4. Carbon dioxide 5. Hydrogen

List the following elements in order from most common to least common in Earth's crust

1. Oxygen 2. Silicon 3. Iron 4. Hydrogen

Create a subsea rift by placing the following steps in their proper order, from start to finish.

1. mantle material is heated deep within earth 2. heated material rises pushing existing material up and sideways 3. adjacent plates are driven apart 4. mantle material seeps between plates forming new crust

Describe the process of plate subduction and the creation of a mountain range by arranging the statements in a sensible order.

1. mantle material is heated deep within earth and rises 2. new crust forms at the mid-oceanic ridge pushing the plate sideways 3. at the other edge an ocean plate is driven below a continental plate 4. the interaction wrinkles the continental plate

Put the steps in order to follow the path of energy that heats Earth through the greenhouse effect.

1. visible sunlight is absorbed by earths surface warming it 2. Earth emits blackbody radiation with a peak in the infrared 3. CO2 and H2O in the atmosphere absorb infrared radiation 4. The absorbed infrared light is reradiated some toward space and some toward earth further heating it 5. Earth is now receiving sunlight and the light from the atmosphere earth gets hotter

The asteroid Ceres has a mass of 9.4 × 1020 kg and a volume of about 4.7 × 1020 L (liters). It has an average density (ρ = MV) of about ____.

2 kgL

The half-life of potassium-40 is about 1.3 billion years. If a rock containing 200,000 atoms of potassium-40 was formed 3.9 billion years ago, today we would expect it to contain ___ thousand atoms of potassium.

25

Which of the following is evidence for global warming?

A clear correlation between carbon dioxide levels and Earth's temperature

Match each effect with a cause. A hole in the ozone layer appears annually over Antarctica The global temperature has increased by about 1 degree C since 1880 The ozone hole has been getting smaller since about 2001 It's warmer on cloudy nights

A hole in the ozone layer appears annually over Antarctica - Pollutants reach the polar stratospheric clouds and break up ozone molecules. The global temperature has increased by about 1 degree C since 1880 - There is 20% more carbon dioxide in the air than in 1880 The ozone hole has been getting smaller since about 2001 - Atmospheric pollutants in consumer products have been banned. It's warmer on cloudy nights - Water vapor is a greenhouse gas

Select all of the objects that would be pulled into a spherical shape by gravity, if found out in space.

A solar system-sized cloud of gas A house-sized pool of water

Select all of the objects that cannot be pulled into a spherical shape by gravity, if found out in space.

A typical asteroid in the asteroid belt. The icy nucleus of a comet.

A trans-Neptunian object (TNO) and an asteroid have the same volume, but the mass of the asteroid is three times as much as that of the TNO. Therefore, we expect the density of the asteroid to be _____ times _____. (Choose two.)

Bigger 3

What causes an aurora?

Charged particles from the Sun interact with our magnetic field, exciting ions in Earth's atmosphere, which then emit light.

Select all the pieces of evidence below that support the idea that Earth's atmosphere was formed by the impact of comets.

Comets are formed of frozen water and gases. Collisions with comets would have been more common in the distant past when comets were more common.

Why is Earth's mantle molten and its outer core liquid, while this is not true of the Moon or Mars? (Select all that apply.)

Earth formed hot and has a high ratio of volume to surface area. Long-lived radioactive elements are in Earth in large quantities.

Why is the surface of Earth warmer than the surface of the Moon?

Earth has an atmosphere, and the Moon doesn't.

Both Earth and the asteroid Gaspra are made of the same materials. Earth is spherical, but Gaspra is not. Why? (Select all that apply.)

Earth is a large, very massive body. Gaspra has a very low mass.

Select all the choices that describe Earth's mantle.

Essentially solid but can flow Mostly olivine (a mineral of Fe, Mg, Si, and O)

Select all the observations that lead us to believe that Earth's interior is hot.

Every 100 m we dig into Earth, the temperature goes up 2 K. Earth has active volcanoes.

Mars is about one and a half times farther from the Sun than Earth is. Which of the following could raise the surface temperature of Mars?

Having a denser atmosphere, especially with greenhouse gases

In convection, why does heated material rise?

Heating decreases density, causing that material to float upward.

Select each atmospheric effect below that is caused by human activity.

Increasing amounts of carbon dioxide in the atmosphere Formation of a hole in the ozone layer

Mars spins at nearly the same rate as Earth, but is much smaller in diameter and lower in mass. Why does it have a much weaker magnetic field than Earth? Select all that apply.

It has a much smaller iron core. It has cooled off inside.

Select all of the following that correctly describe how water vapor behaves in Earth's atmosphere.

It helps remove carbon dioxide from the atmosphere. It can form tiny ice crystals. It is found almost exclusively in the troposphere.

What is happening to Earth's magnetic field?

It is getting weaker and might eventually reverse.

Why is Earth's outer core liquid?

It is hot enough to melt iron.

Select the statements that accurately describe Earth's atmosphere.

It once had little O2 and much more CO2. Oxygen is present because of bacteria and ancient plants.

Venus has nearly the same mass and diameter as Earth and spins much more slowly. Select all that explain why it has a much weaker magnetic field.

It spins too slowly.

Select the correct descriptions of Earth's outer core.

Liquid (flowing) About 2300 km wide Mostly iron and nickel

Select all the answers that are true about changes in Earth's magnetic field.

Magnetic reversals occur erratically. Changes in Earth's magnetic field explain the stripes of opposite polarity on the ocean floor. The magnetic field hasn't changed direction in about 780,000 years.

Match the components in the atmosphere with their approximate percentage by volume.

Nitrogen - 78% Oxygen - 21% Water vapor - a few percent Carbon dioxide - less than 0.1% Argon - about 1%

Ozone is considered air pollution when we breath it. Why is it useful to have in the stratosphere?

Ozone absorbs ultraviolet light from the Sun, protecting us from the harmful ultraviolet rays.

Match the terms to their definitions. Radioactive decay Radioactive dating Daughter Atom Half-life

Radioactive decay - The spontaneous breakdown of unstable atomic nuclei into smaller nuclei Radioactive dating - A procedure by which scientists measure the age of a sample based on the ratios of parent and daughter atoms Daughter atom - A product of radioactive decay, which may or may not be radioactive itself Half-life - The average length of time for half of the radioactive particles to decay

____ generate(s) heat in Earth's interior, much as happens in a nuclear reactor.

Radioactive elements

Match the feature of the inner core to its cause or the evidence for it.

Solid rather than liquid or gas - Too much pressure to be anything else Made of iron and nickel - The densest materials sink to the core Radius is about 1200 km - Seismic wave detection patterns

Select all of the following that describe the Van Allen radiation belts.

The belts are doughnut shaped regions around Earth. The belts are caused by Earth's magnetic field. The belts are dangerous to humans.

Why does Earth have an equatorial bulge?

The rotation of Earth causes material near the equator to move away from Earth's rotational axis.

Select all that happen to charged particles from the Sun when they encounter Earth's magnetic field.

They move in spirals around the magnetic field lines and can create auroras. Some are deflected by the magnetic field and go around Earth. Many are trapped in the Van Allen belts.

Match the layers of Earth's atmosphere to their descriptions.

Troposphere - The lowest layer of Earth's atmosphere; water vapor circulates, causing weather. Stratosphere - From 12 km to 50 km, this stable layer includes the ozone layer. Ozone layer - This layer absorbs ultraviolet light.

True or false: Volcanic eruptions show us that Earth's interior is hot.

True

Why does humid air (rich with water vapor) tend to rise up in the atmosphere.

Water vapor weighs less than most of the other molecules in the atmosphere.

The choices each represent a property of P or S seismic waves. Select the properties of S waves.

Wave motion is perpendicular to direction of travel. Travel more slowly than the other

Venus has almost the same size and density as Earth. Is it likely to have a solid inner core as well?

Yes, it will have nearly the same pressure squeezing down on its core as Earth does.

Lines representing a magnetic field ____.

always run from one pole to the other (e.g., north to south)

Select the gases below which were common in Earth's atmosphere in the distant past, but are not common anymore.

ammonia methane

Magnetic lines of force ____. (Select all that apply.)

are imaginary lines used to depict the shape and strength of a magnetic field show the direction that compass needles would point emanate from one end of a magnet and loop around it, returning to the other end

Earth has a _______ radius at the equator than at the poles as a result of ______ and ______

bigger inertia rotation

Ultraviolet radiation from the Sun ____. (Choose all that apply.)

can cause sunburns and other tissue damage can destroy living organisms

The early atmosphere of Earth may have formed from ____. (Choose all that apply.)

cometary impacts on Earth gases escaping from the interior of Earth

We can find the number of years since a rock solidified by ____.

comparing the amounts of radioactive elements with their daughter elements

Traveling upward from Earth's surface through the layers of atmosphere, the temperature ___ through the troposphere, then ___ through the stratosphere.

decreases increases

True or false: The Van Allen belts trap radioactive particles.

false

_____ is the force that pulls Earth into a nearly spherical shape.

gravity

A planet with a magnetic field must ____. (Select all that apply.)

have a convecting core be rotating relatively quickly have a core that can conduct electricity

Over the past 800,000 years, an ___ in the levels of carbon dioxide in Earth's atmosphere leads to rising temperatures on Earth.

increase

Electrical currents in the molten (outer) iron core of Earth create Earth's _______ field.

magnetic

To find the average density of a planet, we need to find the planet's ____.

mass and radius

The average density of an object, ρ, is its ____.

mass/volume

The most common element in Earth's crust, by mass, is ____.

oxygen

Silicates at Earth's surface are composed primarily of ____. (Select all that apply.)

oxygen silicon

Most continental mountain ranges on Earth are formed where ____.

plates collide and wrinkle

____ occurs when two tectonic plates pull apart (or the plate breaks and pulls apart), and mantle rock rises up into the gap to form new crust. This often happens in the middle of the oceans. (Select all that apply.)

rifting rift valley

_________ waves, which travel through Earth and can be detected all over the world, are generated by earthquakes.

seismic

Scientists infer the interior structure of Earth by measuring ____, which are generated by earthquakes and travel through the body of the planet.

seismic waves

Rocks, more technically referred to as compounds of oxygen and silicon called ______ , are the most common materials in Earth's crust.

silicates

What is the composition of Earth's mantle?

silicates

It is more difficult to breathe on top of a mountain because ____.

the density of the air is much lower than at sea level

Convection in the mantle can occur because ____.

the material in the mantle can flow. Material heated by the core can rise

The greenhouse effect ____. (Select all that apply.)

traps infrared radiation in the atmosphere slows the rate at which energy that heats Earth is lost (radiated into space) is stronger when there is more water vapor and carbon dioxide in the atmosphere

Rain droplets form from water vapor that condenses at low temperature and then capture atmospheric carbon dioxide as they fall toward the ground. This process is at work in the ____, where most of Earth's atmospheric water vapor is found.

troposphere

The majority of Earth's atmosphere is found in the ____.

troposphere