Chapter 6

Question 1

Which is the most abundant gas in Earth’s atmosphere?

Answer 1

nitrogen

Question 2

What is the ratio of nitrogen to oxygen in Earth’s atmosphere?

Answer 2

4 parts nitrogen to 1 part oxygen

Question 3

The major constituents of Earth’s atmosphere are

Answer 3

77% nitrogen and 21% oxygen.

Question 4

The atmosphere that we are now breathing is the _____ atmosphere Earth has had

Answer 4

third

Question 5

Why did Earth’s earliest atmosphere, composed primarily of hydrogen and helium, not last long?

Answer 5

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

Question 6

What were the dominant gases in Earth’s second atmosphere?

Answer 6

carbon dioxide and nitrogen

Question 7

Billions of years ago, Earth’s atmosphere was composed primarily of carbon dioxide. What happened to much of this carbon dioxide?

Answer 7

dissolved into Earth’s oceans

Question 8

Earth’s atmosphere differs from those of near-neighbor planets Venus and Mars in one important respect:

Answer 8

Earth’s atmosphere has a significant fraction of oxygen

Question 9

Photosynthesis in plants on Earth maintains a balance between which of the two atmospheric gases?

Answer 9

oxygen and carbon dioxide

Question 10

The presence of oxygen in Earth’s atmosphere is thought to result directly from what type of process?

Answer 10

activity biological of plants and animals

Question 11

Ozone in the stratosphere performs an important task that protects life on Earth. What is it?

Answer 11

Ozone absorbs much of the dangerous solar ultraviolet light.

Question 12

An “ozone hole” is

Answer 12

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

Question 13

Which of the following terms does NOT label a region of Earth’s atmosphere or near-Earth environment?

Answer 13

chromosphere

Question 14

In which layer of Earth’s atmosphere is the ozone layer located?

Answer 14

stratosphere

Question 15

Ozone is a gas consisting of

Answer 15

molecules containing three oxygen atoms.

Question 16

Why does the temperature in the stratosphere increase with increasing altitude?

Answer 16

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

Question 17

What is the basic structure of Earth’s atmosphere?

Answer 17

four layers of alternating temperature profiles: temperature decreasing, then increasing, then decreasing, then increasing with altitude

Question 18

The lowest temperature in Earth’s atmosphere is about

Answer 18

200 K

Question 19

In which layer of Earth’s atmosphere does weather occur?

Answer 19

troposphere

Question 20

Earth’s magnetic field is most probably generated by

Answer 20

electric currents in Earth’s electricity-conducting molten core.

Question 21

Earth’s magnetosphere is the

Answer 21

region beyond Earth’s atmosphere where Earth’s magnetic field protects us from the solar wind.

Question 22

What causes the phenomenon of the aurora?

Answer 22

Charged particles from the magnetosphere strike atoms in the upper atmosphere, causing them to emit characteristic colors of light.

Question 23

The names we use for the Moon’s maria were

Answer 23

invented a few hundred years ago after the first telescopic observations of the Moon.

Question 24

Craters are not apparent on Earth at the present time in the abundance seen on the Moon because

Answer 24

plate tectonics has returned cratered surface layers into Earth’s interior, and weathering has obliterated the more recent craters.

Question 25

Most of the craters on the Moon were formed by

Answer 25

bombardment by interplanetary meteoritic material.

Question 26

Why do the larger craters on the Moon have central peaks?

Answer 26

The crater floor rebounded upward after the initial compression from the impact of an interplanetary rock.

Question 27

Maria are

Answer 27

ancient lava floodplains.

Question 28

Major maria on the Moon exist

Answer 28

only on the Earth-facing side.

Question 29

What is the name of a long, winding crack in a lunar mare?

Answer 29

rille

Question 30

The mountain ranges on the Moon are

Answer 30

the walls of craters caused by impacts of large objects early in the geological history of the Moon.

Question 31

What are spring tides?

Answer 31

high tides that are significantly higher than the average high tide

Question 32

Spring tides occur

Answer 32

twice a month, at full and new Moon.

Question 33

When do neap tides occur?

Answer 33

whenever the Earth-Moon line makes a 90° angle to the Earth-Sun line