Unit Test — Unit test Answers

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Which phrase describes the relative age of a rock?

A
uses the law of superposition to determine which rock is older or younger
B
can determine the age based on location of a rock within the same layer
C
requires only one rock to determine the age
D
can provide the exact age of a rock
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Which best explains a primary reason for the inability of life to exist in Earth’s early atmosphere?

A
There was insufficient energy from material collisions to change their density.
B
High temperatures during Precambrian time caused surface water evaporation.
C
Volcanic eruptions and comet collisions added different gases to the atmosphere.
D
Available oxygen was used to help create an ozone layer within Earth’s atmosphere.
5

The image shows flat sedimentary rock layers in the foreground and angled sedimentary rock layers in the background.

Question illustration
A
They cracked at an angle.
B
They were deposited at an angle.
C
They were deposited vertically and then shifted by a geologic event.
D
They were deposited horizontally and then shifted by a geologic event.
6

For which object would a geologist use carbon-14 dating to determine age?

A
The bones of animals
B
Rocks older than 50,000 years old
C
Types of Sedimentary rocks
D
Parts of Volcanic rock
7

Which best describes eras and periods?

A
Eras have a smaller time span than periods.
B
Eras and periods are independent of each other.
C
Eras and periods both appear at the start of the Cambrian period.
D
Eras were more recently established on the time scale than periods.
8

After two half-lives, how much of the original material has decayed?

A
25 percent
B
50 percent
C
75 percent
D
100 percent
9

Which correctly lists the three isotopes that geologists measure to determine the age of an organism’s remains?

A
argon, nitrogen, and carbon-12
B
carbon-14, nitrogen, and carbon-12
C
nitrogen, potassium, and carbon-14
D
carbon-12, potassium, and argon
10

Which is the first step in the process during the formation of molded fossils?

A
Sediment hardens into rock.
B
Sediment is eroded from rock.
C
Organisms are buried under sediment.
D
Organisms' shapes are preserved in rock.
12

Which information can be determined using half-life?

A
age of material
B
type of particle released
C
percentage of rock that has aged
D
number of radioactive particles left
13

Which evidence suggests that several mass extinctions have occurred during Earth's history?

A
Fossils provide information about water level and temperature.
B
Many fossils demonstrate that organisms have changed over time.
C
Fossils of the same species have been found on distant continents.
D
Many fossils of organisms that are no longer living have been discovered.
14

The image shows cross-cutting relationships. B, W, E, and K represent rock layers, and Q represents a fault.

Question illustration
A
Layer K is the oldest.
B
Layer W is the youngest.
C
Fault Q occurred before layer K was deposited.
D
Layers B, W, and E were deposited after fault Q occurred.
15

Study the diagram of the geologic time scale.Which method is most likely used to identify what happened before the start of the Paleozoic era?

Question illustration
A
Scientists study fossils from the Jurassic period.
B
Scientists observe index fossil records of the Mesozoic era.
C
Scientists examine fossil evidence during the Precambrian time.
D
Scientists explore the emergence of mammals and humans in the Cenozoic era.
16

Which statement explains one reason why unconformities occur?

A
Rocks along a fault break and move.
B
Igneous rock forms at Earth’s surface.
C
No sediment is deposited over a long time.
D
Igneous rock forms between sedimentary layers.
17

Which statement accurately describes radioactive dating?

A
Geologists use only one type of radioactive dating.
B
Geologists compare parent and daughter elements to determine rock type.
C
Geologists will measure how stable multiple parent elements can decay into multiple daughter elements.
D
Geologist compare the observed abundance of naturally occurring radioactive isotopes and their decay products using decay rates.
18

Which unit of geologic time is the oldest?

A
Cenozoic
B
Mesozoic
C
Ordovician
D
Precambrian
19

Study the image about geologic time.

Question illustration
A
Quaternary
B
Neogene
C
Paleogene
D
Cenozoic
20

What happens to soft parts of organisms when cast fossils form?

A
They decay.
B
They petrify.
C
They form carbon films.
D
They become part of the fossil.
22

What does the geologic time scale confirm about the Cretaceous period?

A
It ended during the Cenozoic era.
B
It ended during the Mesozoic era.
C
It started before Precambrian time.
D
It started before the Cambrian period.
23

In which situation is the principle of cross-cutting relationships useful in determining relative age?

A
A fault breaks through sedimentary layers.
B
Fossils of two different species are found in different rock layers.
C
Sedimentary layers form over millions of years in a lake bottom.
D
Lava flows form on top of one another from several eruptions over time.
24

Which statement describes what happens to elements during radioactive decay?

A
They release energy.
B
They gain new particles.
C
They lose energy at a varying rate.
D
They have a consistent number of particles.

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