chapter 6a

Why does the temperature in the stratosphere increase with increasing altitude? A) The stratosphere is heated by solar ultraviolet radiation absorbed by the ozone layer. B) Charged particles from the magnetosphere collide with atoms in the stratosphere, depositing energy. C) Higher altitudes are closer to the Sun and are therefore heated more by it. D) The stratosphere is heated by solar infrared radiation absorbed by carbon dioxide and water vapor.

A) The stratosphere is heated by solar ultraviolet radiation absorbed by the ozone layer.

Earth's thermosphere is the A) outermost atmospheric layer in which ultraviolet light from the Sun ionizes atoms. B) intermediate atmospheric layer in which ultraviolet light from the Sun is absorbed by ozone (O3) molecules. C) region of the magnetosphere in which trapped high-energy charged particles spiral along magnetic field lines. D) layer of molten iron and nickel below the mantle.

A) outermost atmospheric layer in which ultraviolet light from the Sun ionizes atoms.

The atmosphere that we are now breathing is the _____ atmosphere Earth has had. A) third B) second C) seventh D) first

A) third

How was the Mid-Atlantic Ridge formed? A) Two crustal plates slid past each other in a transverse fault. B) The weight of sediments caused the ocean floor to sink, and the ridge resulted from slumping toward the center of this basin. C) Molten rock pushed up from Earth's interior and forced two crustal plates apart. D) Two crustal plates collided, causing one plate to buckle, forming the ridge, while the other plate was thrust down beneath it.

C) Molten rock pushed up from Earth's interior and forced two crustal plates apart.

Roughly how much denser was Earth's second atmosphere (i.e., how much gas was there in it?) compared with today's atmosphere? A) same density as the present atmosphere B) 1/10 as dense C) twice as dense D) 100 times denser

D) 100 times denser

The major constituents of Earth's atmosphere are A) 95% carbon dioxide and some water vapor. B) about equal amounts of methane, ammonia, water vapor, and carbon dioxide, C) 77% oxygen and 21% nitrogen. D) 77% nitrogen and 21% oxygen.

D) 77% nitrogen and 21% oxygen.

Which of the following statements about Earth is true? A) The oxygen in Earth's atmosphere was created by the evaporation of seawater and its dissociation into hydrogen and oxygen by solar UV light. B) Earth has always had an oxygen-rich atmosphere, which was one reason that life could develop on Earth. C) Out-gassing by volcanic eruptions converted the carbon-dioxide-rich atmosphere into an oxygen-rich atmosphere, thus creating conditions in which life could develop. D) Life developed in a carbon-dioxide-rich atmosphere and then converted it into an oxygen-rich atmosphere.

D) Life developed in a carbon-dioxide-rich atmosphere and then converted it into an oxygen-rich atmosphere.

The internal structure of Earth is a A) core of solid rock extensively enriched in iron, surrounded by a solid mantle of pure rock. B) large, solid iron core surrounded by a thick, flexible mantle of rock. C) core of rock and iron, surrounded by a mantle of liquid hydrogen. D) large core of iron, partly solid and partly molten, surrounded by a thick, flexible mantle of rock.

D) large core of iron, partly solid and partly molten, surrounded by a thick, flexible mantle of rock.

Why did Earth's earliest atmosphere, composed primarily of hydrogen and helium, not last long? A) Hydrogen is highly reactive, and it soon became bound into chemical compounds in Earth's rocks. B) Hydrogen and helium are light gases, and they soon escaped into space. C) Biological activity very quickly combined the hydrogen with oxygen to form water. D) The hydrogen soon became dissolved in Earth's oceans.

B) Hydrogen and helium are light gases, and they soon escaped into space.

Ozone in the stratosphere performs an important task that protects life on Earth. What is it? A) Ozone absorbs the solar wind as it streams into Earth, thereby protecting life from dangerous ionizing radiation. B) Ozone absorbs much of the dangerous solar ultraviolet light. C) Ozone acts as a disinfectant, killing dangerous viruses and bacteria that drift in all the time from space before they can reach Earth. D) Ozone absorbs infrared radiation, thereby providing a comfortable atmospheric temperature on the surface of Earth.

B) Ozone absorbs much of the dangerous solar ultraviolet light.

Photosynthesis is a chemical process that takes place in green plants. What is its effect on our atmosphere? A) Photosynthesis consumes carbon dioxide from our atmosphere but produces carbon dioxide at the end of the process and thus has little effect on our atmosphere. B) Photosynthesis consumes carbon dioxide from our atmosphere and produces oxygen. C) Photosynthesis consumes oxygen from our atmosphere and produces carbon dioxide. D) Photosynthesis consumes both water vapor and carbon dioxide from our atmosphere and produces nitrogen.

B) Photosynthesis consumes carbon dioxide from our atmosphere and produces oxygen.

An "ozone hole" is A) a region centered on the equator where ozone levels are always very low because of destruction by direct sunlight. B) a region of the stratosphere above the South Pole where ozone levels occasionally drop to very low levels. C) the name given to small pits or holes on the aluminum surface of an aircraft, etched by the corrosive ozone encountered in the stratosphere and requiring regular maintenance. D) a permanent region of very low ozone content in the stratosphere centered over the south pole that has been there for thousands of years; the resulting transparency to UV radiation accounts for the lack of life forms there.

B) a region of the stratosphere above the South Pole where ozone levels occasionally drop to very low levels.

What were the dominant gases in Earth's second atmosphere? A) nitrogen and oxygen B) carbon dioxide and nitrogen C) methane and ammonia D) hydrogen and helium

B) carbon dioxide and nitrogen

Which of the following events would NOT be a consequence of the destruction of the ozone layer on Earth? A) large-scale (perhaps total) destruction of life on Earth B) large-scale freezing of the oceans C) drastic increase in ultraviolet radiation at Earth's surface D) elimination of the rise in temperature in the stratosphere

B) large-scale freezing of the oceans

Why is the core of Earth made up predominantly of the heavy element iron? A) Chemical processes refined iron from iron oxides and other compounds in primordial rocks at the high temperatures of Earth's core, similar to present-day iron ore processing. B) Nuclear reactions in the very hot early core of Earth produced iron from lighter elements by nuclear fusion. C) The heavy elements sank slowly to the center during early molten phases in Earth's geological history. D) The heavy elements came together first out of the primordial dust and gas to form the initial Earth because of their greater density and gravitational attraction, and this core then attracted lighter rocks to its surface.

C) The heavy elements sank slowly to the center during early molten phases in Earth's geological history.

Why is it that terrestrial planets are thought to have dense iron cores? A) Thermonuclear reactions produced iron as a fusion product in the earlier phases of planetary evolution (thermonuclear accretion). B) During the formation of the planets, heavy elements accumulated first, followed by the accretion of lighter elements onto them (bimodal accretion). C) The planets were molten early in their life, and the heavy elements sank and lighter materials floated to the surface (planetary differentiation). D) Magnetism in the iron was sufficiently powerful to pull iron atoms to the center as the planet formed (magnetic sorting).

C) The planets were molten early in their life, and the heavy elements sank and lighter materials floated to the surface (planetary differentiation).

Ozone is a gas consisting of A) molecules containing combinations of oxygen and nitrogen atoms and electrons. B) a mixture of several chlorofluorocarbon gases (CFCs). C) molecules containing three oxygen atoms. D) ionized oxygen atoms, positively charged.

C) molecules containing three oxygen atoms.

Earth's stratosphere is warmer than the layers above and below it because A) the methane released when we burn fossil fuel collects in this layer and absorbs infrared light. B) warm air heated by contact with the ground rises into the stratosphere and heats it. C) ozone in the stratosphere absorbs specific wavelengths of ultraviolet radiation from the Sun. D) carbon dioxide in the stratosphere absorbs infrared light radiated outward by the ground.

C) ozone in the stratosphere absorbs specific wavelengths of ultraviolet radiation from the Sun.

One of the major differences between Earth and its neighboring planets Venus and Mars is the lack of large quantities of CO2 in its atmosphere. If all three planets were originally formed with significant quantities of this gas in their atmospheres, where is the majority of this CO2 on Earth at the present time? A) dissociated by UV and visible sunlight into carbon and oxygen that now exist in abundance as separate chemicals B) concentrated high in the atmosphere where it contributes to the greenhouse effect C) dissolved in seawater, a situation that cannot arise on the neighboring planets. D) locked up in carbonate and carbon-rich rocks and minerals formed in the sea and on Earth's surface

D) locked up in carbonate and carbon-rich rocks and minerals formed in the sea and on Earth's surface

What are the major layers of Earth's atmosphere in the correct order from the surface upward? A) stratosphere, mesosphere, thermosphere, troposphere B) mesosphere, troposphere, thermosphere, stratosphere C) thermosphere, mesosphere, troposphere, stratosphere D) troposphere, stratosphere, mesosphere, thermosphere

D) troposphere, stratosphere, mesosphere, thermosphere

The San Andreas fault in California is an example of A) two tectonic plates pushing directly against one another. B) an upthrust due to a hot spot in Earth's mantle. C) a spreading center, where two tectonic plates are being pushed away from each other. D) two tectonic plates sliding past each other.

D) two tectonic plates sliding past each other.