Unit Test — Unit test Answers

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1
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Which best explains how scientists confirmed that the moon formed around the same time as Earth?

A
Scientists determined the approximate age of fossils from the moon and Earth.
B
Scientists used radioactive dating to study the age of material from the moon and Earth.
C
Scientists explored the cycle of condensation and evaporation over time on the moon and Earth.
D
Scientists analyzed the content of gases that were part of the atmospheres on the moon and Earth.
2
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The diagram illustrates radioactive decay.

Question illustration
A
Structure 1 is an unstable atom that turns into structure 2, a new atom.
B
Structure 1 is a stable element that breaks down into structure 2, an unstable element.
C
Structure 1 is a radioactive element that loses particles to create structure 2, released energy.
D
Structure 1 is a radioactive atom that decays into structure 2, half of the original unstable element.
3

Which method preserves an image of a leaf?

A
The leaf turns into rock over time.
B
Tree sap flows over the leaf and preserves it.
C
Sediment covers the leaf and leaves an imprint on the rock.
D
As the leaf decomposes, carbon from the leaf is left on the rock.
4

Study the timeline.

Question illustration
A
5 million years
B
200 million years
C
1.5 billion years
D
4.5 billion years
5

Which is an example of a trace fossil?

A
animal burrow
B
skin of organism
C
preserved bone
D
petrified wood
6

Which characteristic of potassium makes it useful for dating rocks?

A
It has a long half-life.
B
It decays at an unknown rate.
C
It produces lead as it breaks down.
D
It can be used to date all types of rock.
7

What determines the length of a geologic time period?

A
fossil record
B
material density
C
meteors and rocks
D
radioactive materials
8

Which statement describes potassium-argon dating?

A
Potassium-40 decays into argon gas over time.
B
Argon breaks down into other elements and compounds.
C
Potassium-40 becomes stable when trapped in rocks.
D
Argon is unstable and will decay into potassium-40 over time.
9

The image shows locations of fossils from different geologic periods in Virginia.Which association correctly links the time period with the location of the fossils?

Question illustration
A
Pennsylvanian eastern and western Virginia
Option A
B
Cambrian throughout southern Virginia
Option B
C
Tertiary eastern Virginia
Option C
D
Quaternary eastern and western Virginia
Option D
10

Which statement accurately describes a half-life?

A
A rock’s size is determined by half-life.
A
All stable and unstable elements have a half-life.
A
An atom of an element becomes half its original size in a half-life.
A
A half-life is the time required for half of a radioactive element to decay.
11

Which important event in Earth’s history occurred during the Jurassic period?

T
The first birds emerged on Earth.
M
Mammals were in search of food.
A
Animals with shells emerged on Earth
T
Treelike ferns first began to grow and populate.
13

Which statement describes the law of superposition?

A
Sedimentary rocks were originally in horizontal layers.
B
In horizontal rock layers, each layer is younger than the one below it.
C
Rock layers must be in existence before something can happen to them.
D
Rocks that are not in horizontal layers were shifted by some geologic event.
14

Which phrase describes faults?

A
cause gaps in the geologic record
B
cause rocks to break and move
C
are older than surrounding rocks
D
are igneous rocks that form beneath Earth’s surface

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