AnswersCentral 25-26 CR SCI 100A FallUnit Test

Unit Test — Cumulative exam Answers

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

A
The first birds emerged on Earth.
B
Mammals were in search of food.
C
Animals with shells emerged on Earth
D
Treelike ferns first began to grow and populate.
2
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Which phrase best describes igneous rocks?

A
form when lava and magma cool
B
accumulate sediments following erosion
C
require heat and pressure to be formed
D
consist of many sediment layers
3

Observable matter makes up about what percentage of the universe?

A
5%
B
10%
C
50%
D
95%
4

Which type of reaction does this diagram represent?

Question illustration
A
a chain reaction that is caused by nuclear fission
B
a chain reaction that is caused by nuclear fusion
C
a decrease in energy that is caused by nuclear fission
D
an increase in energy that is caused by nuclear fusion
5

Which statement best explains why Earth’s outer core is in liquid form?

A
The iron-nickel alloy melts due to hot temperatures.
B
The outer core has a tarry consistency.
C
This region is less dense when compared to the mantle.
D
This region is under extreme pressure from the weight of other layers.
6

What was discovered in 1965 and is believed to be leftover thermal energy from the big bang?

A
red shift
B
the Eagle Nebula
C
the Doppler effect
D
background radiation
7

How long ago do scientists believe the continents formed Pangaea?

A
about 135 million years ago
B
about 180 million years ago
C
about 300 million years ago
D
about 4.5 billion years ago
8

Which coal field location is related to coal fields in the United States and supports the theory of continental drift?

A
India
B
Africa
C
Australia
D
Europe
9

Which statement is an example of an observation a scientist would make to classify a rock?

A
A rock is larger than other rocks.
B
A rock was found in a stream.
C
A rock is formed from molten lava.
D
A rock cracks in half after a rainstorm.
10

Which best describes nuclear fusion?

A
A nucleus spontaneously splits and absorbs energy.
B
Two nuclei spontaneously combine and absorb energy.
C
A nucleus collides with a neutron and splits, releasing energy.
D
Nuclei combine to form a heavier nucleus, releasing energy.
11

Study the image of this rock.

Question illustration
A
jagged
B
oval
C
round
D
smooth
12

Why do scientists study seismographs?

A
to learn about different rock samples
B
to determine the location of an epicenter
C
to analyze mineral content from Earth’s crust
D
to observe temperature changes on Earth’s surface
13

Which example is indirect evidence used to study Earth’s interior?

A
composition of minerals in a rock
B
age of a rock from within Earth
C
location of an earthquake’s epicenter
D
texture of different core samples
14

The table shows the thickness, top density, and bottom density of the different layers of the Earth. Thickness (km)Density (g/cm3)Types of Rock FoundTopBottomCrust302.22.9Silicic rocksUpper mantle7203.44.4PeridotiteLower mantle2,1714.45.6Magnesium and silicon oxidesOuter core2,2599.912.2Iron+oxygenInner core1,22112.813.1Iron+oxygen

A
As depth increases, the density of the layers increases.
B
As depth increases, the density of the layers decreases.
C
As depth increases, the thickness of the layers increases.
D
As depth increases, the thickness of the layers decreases.
15

Which best describes what forms in nuclear fission?

A
two smaller, more stable nuclei
B
two larger, less stable nuclei
C
one smaller, less stable nucleus
D
one larger, more stable nucleus
16

What determines the length of a geologic time period?

A
fossil record
B
material density
C
meteors and rocks
D
radioactive materials
17

Which process forms sedimentary rock in the rock cycle after sediments accumulate and combine?

A
Sediments undergo heat and pressure.
B
Sedimentary rock weathers and erodes.
C
Sediments compact and cement together.
D
Sedimentary rock experiences cooling and melting.
18

Consider the three equations below.Which statement do these reactions best support?

Question illustration
A
Beta decay occurs only in certain atoms.
B
Alpha decay occurs only in certain atoms.
C
Chain reactions play important roles in the process of nuclear fission.
D
Nuclear fusion plays an important role in making elements that are heavier than helium.
19

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.
20

What happened to the giant landmass that Wegener described?

A
The pieces remained the same shape over time.
B
The pieces moved quickly to their current locations.
C
The pieces moved toward one another and created mountains.
D
The pieces broke apart and drifted away from one another over time.

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