ACT Practice Test 4 doc

ACT Practice Test 4
READING
Passage XIII
HUMANITIES: The following passage is
excerpted from A Short History of Western
Civilization by John Harrison, Richard Sulli-
van, and Dennis Sherman. (©1990 by
McGraw-Hill. Reprinted by permission.)
Enlightenment ideas were put forth by
a variety of intellectuals who in France came
to be known as the philosophes. Philosophes
is French for philosophers, and in a sense
these thinkers were rightly considered [5]
philosophers, for the questions they dealt
with were philosophical: How do we discov-
er truth? How should life be lived? What is
the nature of God? But on the whole the
term has a meaning different from the usual [10]
meaning of “philosopher.” The philosophes
were intellectuals, often not formally trained
or associated with a university. They were
usually more literary than scientific. They
generally extended, applied, popularized, or [15]
propagandized ideas of others rather than
originating those ideas themselves. The
philosophes were more likely to write plays,
satires, pamphlets or simply participate in
verbal exchanges at select gatherings than to [20]
write formal philosophical books.
It was the philosophes who developed
the philosophy of the Enlightenment and

spread it to much of the educated elite in
Western Europe (and the American [25]
colonies). Although the sources for their
philosophy can be traced to the Scientific
Revolution in general, the philosophes were
most influenced by their understanding of
Newton, Locke, and English institutions. [30]
The philosophes saw Newton as the
great synthesizer of the Scientific Revolution
who rightly described the universe as
ordered, mechanical, material, and only
originally set in motion by God, who since [35]
then has remained relatively inactive. New-
ton’s synthesis showed to the philosophes
that reason and nature were compatible:
Nature functioned logically and discernibly,
and what was natural was also reasonable. [40]
Newton exemplified the value of reasoning
based on concrete experience. The
philosophes felt that his empirical method-
ology was the correct path to discovering
truth. [45]
John Locke (1632-1704) agreed with
Newton but went further. This English
thinker would not exempt even the mind
from the mechanical laws of the material
universe. In his Essay Concerning Human [50]
Understanding (1691), Locke pictured the
human brain at birth as a blank sheet of
paper on which nothing would ever be writ-

ten except sense perception and reason.
What human beings become depends on [55]
their experiences—on the information
received through the senses. Schools and
social institutions could therefore play a
great role in molding the individual from
childhood to adulthood. Human beings [60]
were thus by nature far more malleable
than had been assumed. This empirical
psychology of Locke rejected the notion
that human beings were born with innate
ideas or that revelation was a reliable [65]
source of truth. Locke also enunciated lib-
eral and reformist political ideas in his Sec-
ond Treatise of Civil Government (1690),
which influenced the philosophes. On the
whole, Locke’s empiricism, psychology and [70]
politics were appealing to the philosophes.
England, not coincidentally the coun-
try of Newton and Locke, became the
admired model for many of the
philosophes. They tended to idealize it, but [75]
England did seem to allow greater individ-
ual freedom, tolerate religious differences,
and evidence greater political reform than
other countries, especially France. England
seemed to have gone furthest in freeing [80]
itself from traditional institutions and
accepting the new science of the seven-
teenth century. Moreover, England’s

approach seemed to work, for England was
experiencing relative political stability and [85]
prosperity. The philosophes wanted to see
in their own countries much of what Eng-
land already seemed to have.
Many philosophes reflected the influ-
ence of Newton, Locke, and English insti- [90]
tutions, but perhaps the most representa-
tive in his views was Voltaire (1778). Of all
leading figures of the Enlightenment, he
was the most influential. Voltaire, the son
of a Paris lawyer, became the idol of the [95]
French intelligentsia while still in his early
twenties. His versatile mind was sparkling;
his wit was mordant. An outspoken critic,
he soon ran afoul of both church and state
authorities. First he was imprisoned in the [100]
Bastille; later he was exiled to England.
There he encountered the ideas of Newton
and Locke and came to admire English par-
liamentary government and tolerance. In
Letters on the English (1732), Elements of [105]
the Philosophy of Newton (1738), and other
writings, he popularized the ideas of New-
ton and Locke, extolled the virtues of Eng-
lish society, and indirectly criticized French
society. Slipping back into France, he was [110]
hidden for a time and protected by a
wealthy woman who became his mistress.
Voltaire’s facile mind and pen were never

idle. He wrote poetry, drama, history,
essays, letters, and scientific treatises— [115]
ninety volumes in all. Few people in history
have dominated their age intellectually as
did Voltaire.
99. According to the passage, the philosophes can best be described as:
A. writers swept up by their mutual admiration of John Locke.
B. professors who lectured in philosophy at French universities.
C. intellectuals responsible for popularizing Enlightenment ideas.
D. scientists who furthered the work of the Scientific Revolution.
100. Based on information provided in the passage, which of the following would most
likely have been written by Voltaire?
F. A treatise criticizing basic concepts of the Scientific Revolution
G. A play satirizing society in France
H. A collection of letters mocking the English Parliament
J. A sentimental poem expounding the virtues of courtly love
101. According to the passage, Locke felt that schools and social institutions could “play
a great role in molding the individual” (lines 58-59) because:
A. human beings were born with certain innate ideas.
B. human nature becomes more malleable with age.
C. society owes each individual the right to an education.
D. the human mind is chiefly influenced by experience.
102. Based on the information in the passage, which of the following best describes
Newton’s view of the universe?
I. -The universe was initially set in motion by God.
II. -Human reason is insufficient to understand the laws of nature.
III. -The universe operates in a mechanical and orderly fashion.
F. I only
G. I and II only
H. I and III only

J. II and III only
103. According to the passage, which of the following works questioned the idea that
revelation was a reliable source of truth?
A. Letters on the English
B. Second Treatise of Civil Government
C. Elements of the Philosophy of Newton
D. Essay Concerning Human Understanding
104. The passage supports which of the following statements concerning the relationship
between Newton and Locke?
F. Locke’s psychology contradicted Newton’s belief in an orderly universe.
G. Locke maintained that Newton’s laws of the material universe also applied to
the human mind.
H. Newton eventually came to accept Locke’s revolutionary ideas about the
human mind.
J. Newton’s political ideas were the basis of Locke’s liberal and reformist
politics.
105. According to the passage, the philosophes believed that society should:
I. -allow individuals greater freedom.
II. -free itself from traditional institutions.
III. -tolerate religious differences.
A. I only
B. I and II only
C. II and III only
D. I, II, and III
106. It can be inferred from the passage that the authors regard England’s political
stability and economic prosperity as:
F. the reason that the philosophes did not idealize England’s achievement.
G. evidence that political reforms could bring about a better way of life.
H. the result of Voltaire’s activities after he was exiled to England.
J. an indication that the Scientific Revolution had not yet started there.

107. The passage suggests that the French political and religious authorities during the
time of Voltaire:
A. allowed little in the way of free speech.
B. overreacted to Voltaire’s mild satires.
C. regarded the philosophes with indifference.
D. accepted the model of English parliamentary government.
108. As it is used in the passage, treatises (line 115) most nearly means:
F. formal agreements about trade or peace made between two or more countries.
G. extensive written discussions or examinations of specific topics.
H. documents detailing agreements on specific issues.
J. narratives designed to teach moral lessons.
Passage XIV
NATURAL SCIENCE: This passage is taken
from “The Quasar 3C 273” by Thierry Cour-
voisier and E. Ian Robinson. It originally
appeared in Scientific American, June 1991,
Volume 264. Reprinted by permission.
The quasar 3C 273 lies about one-fifth
of the way from the Earth to the edge of the
known universe. Of all the objects in the
cosmos, only a few other quasars surpass the
energy and activity of 3C 273. On an average [5]
day, it is more luminous than 1,000 galaxies,
each containing 100 billion stars. During
one remarkable day in February, 1988, the
quasar erupted with a burst of radiation
equivalent to lighting up stars the size of our [10]
sun at the rate of 10 million per second.
By monitoring 3C 273 in all domains of
the electromagnetic spectrum and by

observing variations in its luminosity,
astronomers have begun to understand [15]
quasars and the physical processes that
power them.
Since quasars were first identified some
28 years ago, astronomers have come to real-
ize that quasars are the cores of extremely [20]
active galaxies. Quasars are unmatched in
luminosity and hence are the most distant
objects that can be detected in the universe.
One of the most important discoveries
about quasars is that their luminosity can [25]
vary greatly over periods of less than a year.
This variability led investigators to the con-
clusion that the tremendous energy of
quasars is radiated from a region many
times smaller than the cores of ordinary [30]
galaxies.
Quasars are powered by the gravitation-
al energy that is released as gas and dust fall
toward their massive, dense centers. Some of
this energy channels particles into beams, [35]
blasting material out into the host galaxy at
speeds close to that of light. Most of the
energy is converted into radiation by a wide
range of physical processes, probably occur-
ring at different distances from the core. Yet [40]
quasars exhibit many phenomena that can-
not be explained, and they remain one of
the most puzzling objects in the universe.

On the whole, we know more about 3C
273 than any other quasar. It possesses a [45]
very wide range of properties, not all of
which are shared by all quasars. The wealth
of activity displayed by 3C 273, however, is a
key in helping astronomers understand the
phenomena at work in quasars. [50]
The task of observing 3C 273 is as chal-
lenging as it is rewarding. After traveling
through space for more than a billion years,
only a tiny fraction of the radiation from 3C
273 reaches the Earth. Capturing this radia- [55]
tion requires frequent observations using a
battery of ground-based telescopes and
satellite-borne instruments.
The effort began more than a century
ago. The object known today as 3C 273 was [60]
first recorded on photographic plates as
astronomers surveyed the stars in the con-
stellation Virgo. It looked like nothing more
than an ordinary, moderately bright star.
Then in 1962, Cyril Hazard and his col- [65]
leagues at Sydney University discovered that
the starlike object occupied the same posi-
tion in the sky as a strong source of radio
waves. The radio emitter had been previous-
ly identified as 3C 273, which stood for [70]
number 273 in the Third Cambridge Cata-
logue of Radio Sources. Objects such as 3C
273 were subsequently described as quasi-

stellar radio sources, or quasars.
In 1963, Maarten Schmidt of the [75]
Mount Wilson and Palomar Observatories
deduced that the quasar 3C 273 was about
three billion light-years away from the
Earth. The implications of this discovery
were extraordinary. The quasar was by far [80]
the most luminous and distant object ever
observed. Soon a few other quasars were
identified that seemed to be even farther
and brighter than 3C 273. At the time, many
of Schmidt’s colleagues had good reason to [85]
question these results. Yet as modern
astronomers review the evidence collected
during the past 28 years, we find little room
to doubt that Schmidt was right.
109. According to the passage, astronomers study quasars and the physical processes that
power them by:
A. observing 3C 273 through ground-based telescopes.
B. monitoring the electromagnetic spectrum of 3C 273.
C. enlarging satellite photographs of distant galaxies.
D. investigating phenomena that cannot be easily explained.
110. According to the passage, what characteristic of quasars makes them the most
distant objects that can be detected in the universe?
F. Their density
G. Their size
H. Their luminosity
J. Their puzzling behavior
111. According to the passage, which of the following describes a characteristic of
quasars?

I They blast material out into host galaxies.
II They convert gravitational energy into radiation.
III. -They possess cores the size of ordinary galaxies.
A. I only
B. I and II only
C. II and III only
D. I, II, and III
112. The passage suggests that observing 3C 273 is as “challenging as it is rewarding”
(lines 51-52) because:
F. there are many unexplained phenomena related to quasars.
G. very little radiation from 3C 273 actually reaches the Earth.
H. scientists have been attempting to study 3C 273 for over a century.
J. the technology required to observe 3C 273 is still being developed.
113. As it is used in line 46, the word properties most likely means:
A. characteristics.
B. possessions.
C. objects.
D. resources.
114. The passage suggests that which of the following is true concerning the growth of
scientific knowledge about quasars?
F. Despite some early skepticism, scientists today still believe that Schmidt’s
conclusions are accurate.
G. While Hazard’s discovery was immediately accepted, Schmidt’s deductions
were ridiculed by his colleagues.
H. Although Hazard’s discovery has proved significant, much remains
questionable regarding Schmidt’s deductions from that data.
J. While Hazard’s discovery was an accident, Schmidt’s discovery was the result
of careful analysis.
115. From the passage, it is most reasonable to conclude that observers originally
thought that quasar 3C 273 was:

A. a radio emitter.
B. a nearby galaxy.
C. an ordinary star.
D. a typical quasar.
116. In the passage, which of the following is NOT a fact provided about quasar 3C 237?
F. It is typically more luminous than 1,000 galaxies.
G. Its luminosity can vary, with some extreme peaks of radiation production.
H. All quasars have the same properties as 3C 237.
J. Radiation from 3C 237 takes more than a billion years to reach Earth.
Passage XV
NATURAL SCIENCE: The following passage
is excerpted from “The Transformer” by John
W. Coltman. (©1988 by Scientific American.)
The transformer is an essential compo-
nent of modern electric power systems.
Simply put, it can convert electricity with a
low current and a high voltage into electric-
ity with a high current and low voltage (and [5]
vice versa) with almost no loss of energy.
The conversion is important because elec-
tric power is transmitted most efficiently at
high voltages but is best generated and used
at low voltages. Were it not for transformers, [10]
the distance separating generators from
consumers would have to be minimized,
many households and industries would
require their own power stations, and elec-
tricity would be a much less practical form [15]
of energy.
In addition to its role in electric power

systems, the transformer is an integral com-
ponent of many things that run on electrici-
ty. Desk lamps, battery chargers, toy trains, [20]
and television sets all rely on transformers to
cut or boost voltage. In all its multiplicity of
applications, the transformer can range from
tiny assemblies the size of a pea to behe-
moths weighing 500 tons or more. This arti- [25]
cle will focus on the transformers in power
systems, but the principles that govern the
function of electrical transformers are the
same regardless of form or application.
The English physicist Michael Faraday [30]
discovered the basic action of the trans-
former during his pioneering investigations
of electricity in 1831. Some fifty years later,
the advent of a practical transformer, con-
taining all the essential elements of the [35]
modern instrument, revolutionized the
infant electric lighting industry. By the turn
of the century, alternating-current power
systems had been universally adopted and
the transformer had assumed a key role in [40]
electrical transmission and distribution.
Yet the transformer’s tale does not end
in 1900. Today’s transformers can handle
500 times the power and 15 times the volt-
age of their turn-of-the-century ancestors; [45]
the weight per unit of power has dropped by
a factor of ten and efficiency typically

exceeds 99 percent. These advances reflect
the marriage of theoretical inquiry and
engineering that first elucidated and then [50]
exploited the phenomena governing trans-
former action.
Faraday’s investigations were inspired
by the Danish physicist Hans Christian Oer-
sted, who had shown in 1820 that an electric [55]
current flowing through a conducting mate-
rial creates a magnetic field around the con-
ductor. At the time, Oersted’s discovery was
considered remarkable, since electricity and
magnetism were thought to be separate and [60]
unrelated forces. If an electric current could
generate a magnetic field, it seemed likely
that a magnetic field could give rise to an
electric current.
In 1831, Faraday demonstrated that in [65]
order for a magnetic field to induce a cur-
rent in a conductor, the field must be chang-
ing. Faraday caused the strength of the field
to fluctuate by making and breaking the
electric circuit generating the field; the same [70]
effect can be achieved with a current whose
direction alternates in time. This fascinating
interaction of electricity and magnetism
came to be known as electromagnetic
induction. [75]
117. According to the passage, the first practical transformer was developed in:
A. 1820.

B. 1831.
C. 1881.
D. 1900.
118. The passage suggests that advances in the efficiency of the transformer are:
F. based solely on Faraday’s discovery of electromagnetic induction.
G. due to a combination of engineering and theoretical curiosity.
H. most likely at a peak that cannot be surpassed.
J. found in transformers that weigh 500 tons or more.
119. According to the passage, Oersted’s discovery concerning the production of a
magnetic field was considered remarkable because:
A. the transformer had not yet been universally adopted.
B. Faraday had already demonstrated that this was impossible.
C. scientists believed that there was no relationship between electricity and
magnetism.
D. it contradicted the established principles of electromagnetism.
120. Which of the following is NOT true of transformers today as compared to the first
transformers?
F. they are lighter in weight.
G. they are many times more powerful.
H. they operate at a much lower voltage.
J. they are almost completely efficient.
121. According to the passage, Oersted’s discovery proved that:
A. magnetism and electricity are unrelated forces.
B. a magnetic field can induce an electric current.
C. all materials that conduct electricity are magnetic.
D. an electric current can create a magnetic field.
122. According to the passage, one function of the transformer is to:
F. convert electricity into the high voltages best for transmission.
G. create the magnetic fields used in industry.
H. minimize the distance between generators and consumers.

J. protect electric power systems from energy loss.
123. Which of the following statements is best supported by the passage?
A. Faraday was the first to show how an electric current can induce an electric
field.
B. Oersted was the first to utilize transformers in a practical application, by using
them to power electric lights.
C. Oersted coined the term “electromagnetic induction.”
D. Faraday demonstrated that when a magnetic field is changing, it can produce an
electric current in a conducting material.
124. According to the passage, electricity would be a much less practical form of energy
if there were no transformers because:
F. generating electricity would become much more expensive.
G. there would be no dependable source of electric power.
H. generators would have to be built close to the consumers they supply.
J. industries and households would have to be supplied with the same power.
Passage XVI
NATURAL SCIENCE: This passage from a
textbook about the solar system discusses
research examining the possibility of life on
Mars.
When the first of the two Viking Lan-
ders touched down on Martian soil on July,
1976, and began to send camera images back
to Earth, the scientists at the Jet Propulsion
Laboratory could not suppress a certain [5]
nervous anticipation, like people who hold a
ticket to a lottery they have a one-in-a-mil-
lion chance of winning. The first photo-
graphs that arrived, however, did not con-
tain any evidence of life. What was revealed [10]

was merely a barren landscape littered with
rocks and boulders. The view resembled
nothing so much as a flat section of desert—
in fact, the winning entry in a contest at
J.P.L. for the photograph most accurately [15]
predicting what Mars would look like was a
snapshot taken from a particularly arid sec-
tion of the Mojave Desert.
The scientists were soon ready to turn
their attention from visible life to microor- [20]
ganisms. The twin Viking Landers carried
experiments designed to detect organic com-
pounds. Researchers thought it possible that
life had developed on early Mars just as it is
thought to have developed on Earth, through [25]
the gradual chemical evolution of complex
organic molecules. To detect biological
activity, Martian soil samples were treated
with various nutrients that would produce
characteristic by-products if life forms were [30]
active in the soil. The results from all three
experiments were inconclusive. The fourth
experiment heated a soil sample to look for
signs of organic material but found none, an
unexpected result because at least organic [35]
compounds from the steady bombardment
of the Martian surface by meteorites were
thought to have been present.
The absence of organic materials, some
scientists speculated, was the result of intense [40]

ultraviolet radiation penetrating the atmos-
phere of Mars and destroying organic com-
pounds in the soil. Although Mars’ atmos-
phere was at one time rich in carbon dioxide
and thus thick enough to protect its surface [45]
from the harmful rays of the Sun, the carbon
dioxide had gradually left the atmosphere
and been converted into rocks. This means
that even if life had gotten a start on early
Mars, it could not have survived the expo- [50]
sure to ultraviolet radiation when the atmos-
phere thinned. Mars never developed a pro-
tective layer of ozone as Earth did.
Despite the disappointing Viking
results, there are those who still keep open [55]
the possibility of life on Mars. They point
out that the Viking data cannot be consid-
ered the final word on Martian life because
the two landers only sampled limited—and
uninteresting—sites. The Viking landing [60]
sites were not chosen for what they might tell
of the planet’s biology. They were chosen
primarily because they appeared to be safe
for landing a spacecraft. The landing sites
were on parts of the Martian plains that [65]
appeared relatively featureless from orbital
photographs.
The type of terrain that these
researchers suggest may be a possible hiding
place for active life has an Earthly parallel: [70]

the ice-free region of southern Victoria
Land, Antarctica, where the temperatures in
some dry valleys average below zero. Organ-
isms known as endoliths, a form of blue-
green algae that has adapted to this harsh [75]
environment, were found living inside cer-
tain translucent, porous rocks in these
Antarctic valleys. The argument based on
this discovery is that if life did exist on early
Mars, it is possible that it escaped worsening [80]
conditions by similarly seeking refuge in
rocks. Skeptics object, however, that Mars in
its present state is simply too dry, even com-
pared with Antarctic valleys, to sustain any
life whatsoever. [85]
Should Mars eventually prove to be
barren of life, as some suspect, then this
would have a significant impact on the cur-
rent view of the chemical origins of life. It
could be much more difficult to get life [90]
started on a planet than scientists thought
before the Viking landings.
125. The word suppress, as used in line 5, most nearly means:
A. oppose.
B. vanquish.
C. prohibit.
D. stifle.
126. According to the passage, scientists treated Martian soil samples with nutrients in
order to:
F. test for the presence of life-forms.

G. verify the results of their experiments.
H. investigate ways of starting life on other planets.
J. find evidence of meteorite bombardment.
127. According to the passage, scientists expected organic compounds to be present on
Mars as a result of:
A. alien civilizations.
B. ultraviolet radiation.
C. meteor bombardment.
D. atmospheric activity.
128. The passage suggests that an important difference between Mars and Earth is that,
unlike Earth, Mars:
F. accumulated organic compounds in its soil.
G. lies in the path of harmful rays of ultraviolet radiation.
H. once possessed an atmosphere rich in carbon dioxide.
J. could not sustain any life that developed.
129. According to the passage, the surface of Mars most resembles:
A. southern Florida.
B. the Mojave desert.
C. southern Victoria Land.
D. the ice valleys of Antarctica.
130. The main point of the second paragraph (lines 19-38) is that:
F. scientists were disappointed by the inconclusive results of their experiments.
G. theories about how life developed on Earth were shown to be flawed.
H. there was no experimental confirmation that life exists on Mars.
J. meteorite bombardment of the Martian surface is less constant than scientists
predicted.
131. The researchers’ argument that life may exist in Martian rocks rests on the idea that:
A. life evolved in the same way on two different planets.
B. organisms may adopt identical survival strategies in similar environments.
C. life developed in the form of a blue-green algae on Mars.

D. organisms that survived in Antarctica could survive on Mars.
132. According to the passage, the results of the Viking Mission could eventually have a
“significant impact” (line 88) because:
F. future expeditions to Mars may take samples from many different sites.
G. current theories about how life began on Earth may have to be changed.
H. scientists may be forced to acknowledge that life does not exist on other
planets.
J. the focus of research into the evolution of life may shift to Antarctica.
133. According to the passage, any organic materials that existed on Mars were probably
destroyed by:
I ultraviolet radiation.
II carbon dioxide in the atmosphere.
III. -the absence of a layer of ozone.
A. I only
B. I and II only
C. I and III only
D. I, II, and III
134. Which of the following statements is best supported by the fourth paragraph (lines
54-67)?
F. The Viking Mission was unsuccessful due to poor selection of landing sites.
G. The results of the Viking mission do not prove that Mars is devoid of life.
H. The detection of life on Mars was not a primary objective of the Viking
mission.
J. Scientists were not expecting to discover life on the Martian plains.
Passage XVII
NATURAL SCIENCE: The following passage
is excerpted from “Earth’s Ozone Shield
Under Threat” by France Bequette (© Unesco
Courier, June 1990).
The ozone layer, the tenuous layer of

gas that surrounds our planet between
twelve and forty-five kilometers above our
surface, is being rapidly depleted. Seasonally
occurring holes have appeared in it over the [5]
Poles, and, more recently, over the temper-
ate regions of the Northern Hemisphere.
The threat is a serious one since the ozone
layer traps almost all in-coming ultraviolet
radiation, which is harmful to all living [10]
organisms—humans, animals, and plants.
Even though the ozone layer is twenty-
five kilometers thick, the atmosphere in it is
very tenuous, and the total amount of
ozone, compared with other atmospheric [15]
gases, is quite small. If all of the ozone in a
vertical column reaching up through the
atmosphere were to be compressed to sea-
level pressure, it would form a layer only a
few millimeters thick [20]
Detailed study of the ozone layer began
comparatively recently, the earliest observa-
tions being made in 1930 by the English sci-
entist Sydney Chapman. These initial obser-
vations were taken up by the World Meteo- [25]
rological Organization (WMO), which
established the Dobson network of one
hundred observation stations. Since 1983,
on the initiative of WMO and the United
Nations Environment Programme (UNEP), [30]
seven of these stations have been entrusted

with the task of making long-term forecasts
of the likely evolution of our precious
shield.
In 1958, the researchers who perma- [35]
nently monitor the ozone content of the
layer above the South Pole began to observe
several seasonal variations. From June there
was a slight reduction in ozone content that
reached a minimum in October. In Novem- [40]
ber, there was a sudden increase in the ozone
content. The fluctuations appeared to result
from the natural phenomena of wind effects
and temperature change.
However, although the October mini- [45]
mum remained constant until 1979, the
total ozone content over the Pole was steadi-
ly diminishing until, in 1985, public opinion
was finally roused by reports of a “hole” in
the ozone layer and observations were [50]
intensified. The culprits responsible for the
hole had already been identified as being
supersonic aircraft, such as Concorde,
(although these have now been exonerated)
and the notorious compounds known as [55]
chlorofluorocarbons, or CFCs. Synthesized
in 1928 by chemists working at General
Motors in the United States, CFCs are com-
pounds of atoms of chlorine and fluorine.
Having the advantage of being non-flam- [60]
mable, non-toxic and non-corrosive, they

came into widespread use in the 1950s.
They are widely used in refrigerators, air-
conditioners, the “bubbles” in the foam
plastic used, for example, in car seats, and [65]
as insulation in buildings….
In 1989, they represented a market
valued at over $1.5 billion and a labor force
of 1.6 million. Of the twenty-five countries
producing CFCs, the United States, France, [70]
the United Kingdom, Japan and Germany
accounted for three-quarters of the total
world production of some 1.2 million tons.
These figures give some idea of the
importance of the economic interests that [75]
are at stake in any decision to ban the
industrial use of CFCs. But, with CFCs
incriminated by scientists, the question
arose as to whether we were prepared to
take the risk of seeing an increase in the [80]
number of cases of skin cancer, eye ail-
ments such as cataracts, or even a lowering
of the human immune defense system, all
effects that would follow further depletion
of the ozone layer…. [85]
Ozone Layer was the first world agree-
ment aimed at halting the production of
CFCs. As more evidence emerged concern-
ing the seriousness of the threat, it became
apparent that the protocol was not strin- [90]
gent enough and, year by year, its severity

was increased until in 1990 in London, sev-
enty countries agreed to stop all produc-
tion of CFCs by the year 2000….
Unfortunately, even if the entire world [95]
were to agree today to halt all production
and use of CFCs, this would not provide an
immediate solution to the problem. A single
molecule of chlorine can destroy from
10,000 to 100,000 molecules of ozone. Fur- [100]
thermore, CFCs have a lifespan of between
75 and 400 years, and they take ten years to
reach the ozone layer. In other words, what
we are experiencing now results from CFCs
emitted ten years ago. [105]
Industrialists are now urgently search-
ing for substitute products. Some, such as
propane, are too dangerous because they
are flammable; others, the HCFCs, might
prove to be toxic and to contribute to the [110]
greenhouse effect, i.e., to the process of
global warming. Nevertheless, nobody can
say that the situation will not right itself,
whether in the short term or long term, if
we ourselves lend a hand. [115]
135. As it is used in the passage, the term tenuous (lines 1 and 14) most likely means:
A. thin.
B. dangerous.
C. substantial.
D. fragile.
136. According to the passage, the public first became aware of the depletion of ozone

layer in:
F. 1930.
G. 1958.
H. 1979.
J. 1985.
137. According to the passage, all of the following contribute to fluctuations in the
content of the ozone layer EXCEPT:
A. supersonic aircraft.
B. chlorofluorocarbons.
C. temperature changes.
D. wind effects.
138. The main point of the seventh paragraph (lines 67-73) is to:
F. highlight the amount of CFCs produced every year.
G. criticize the countries responsible for producing CFCs.
H. indicate the economic interests at stake in the CFC debate.
J. list the most important members of the Montreal Protocol.
139. According to the passage, alternatives to using CFCs may be difficult to find
because substitute products
I. may prove to be toxic.
II. are too dangerous to use.
III. contribute to global warming.
A. II only
B. II and III only
C. I and II only
D. I, II, and III
140. According to the passage, forecasts about the future of the ozone layer are made by:
F. the WMO.
G. the Dobson network.
H. the Montreal Protocol.
J. the UNEP.

141. Based on information in the passage, which of the following would be the most
likely result if all production of CFCs were to end today?
A. Scientists would have to replace the quantities of ozone already lost.
B. The ozone layer would only return to normal levels after 75 years.
C. Scientists would also have to destroy all chlorine molecules in the atmosphere.
D. The benefits would not be experienced for another ten years.
142. According the passage, the ozone layer is:
F. a few millimeters thick.
G. twelve kilometers thick.
H. twenty-five kilometers thick.
J. over twenty-five kilometers thick.
143. Which of the following statements is best supported by the fourth paragraph (lines
35-44)?
A. The ozone layer undergoes seasonal variations in density.
B. The number of CFCs in the atmosphere increases from June to October.
C. The ozone layer over the South Pole is more at risk than in other areas.
D. The first studies of ozone layer depletion underestimated its severity.
144. The main conclusion reached in the passage about the threat to the ozone layer is
that:
F. the cost of banning CFCs altogether may make it an impractical answer.
G. finding alternative products to CFCs may provide a long-term remedy to the
situation.
H. halting production of CFCs is unlikely to produce a solution to the problem.
J. agreements between CFC-producing countries need to be more strictly
enforced.