To glass researchers it seems somewhat strange that many people throug

Question

To glass researchers it seems somewhat strange
that many people throughout the world share the
persistent belief that window glass flows slowly
downward like a very viscous liquid. Repeated in
  (5)   reference books, in science classes, and elsewhere,
the idea has often been invoked to explain ripply
windows in old houses. The origins of the myth are
unclear, but the confusion probably arose partly from
a misunderstanding of the fact that the atoms in glass
  (10)   are not arranged in a fixed crystal structure. In this
respect, the structure ofliquid glass and the structure
of solid glass are very similar, but thermodynamically
they are not the same. Glass does not have a precise
freezing point; rather, it has what is known as a glass
  (15)   transition temperature, typically a range of a few
hundred degrees Celsius. Cooled below the lower
end of this range, molten glass retains an amorphous
atomic structure, but it takes on the physical properties
of a solid.

(20)   However, a new study debunks the persistent
belief that stained glass windows in medieval cathedrals
are noticeably thicker at the bottom because the glass
flows downward. Under the force of gravity, certain
solid materials including glass can, in fact, flow
  (25)   slightly. But Brazilian researcher Edgar Dutra Zanotto
has calculated the time needed for viscous flow to
change the thickness of different types of glass by a
noticeable amount, and, according to his calculations,
medieval cathedral glass would require a period well
  (30)   beyond the age of the universe.

The chemical composition of the glass determines
the rate of flow. Even germanium oxide glass, which
flows more easily than other types, would take many
trillions of years to sag noticeably, Zanotto calculates.
  (35)   Medieval stained glass contains impurities that could
lower the viscosity and speed the flow to some degree,
but even a significant difference in this regard would
not alter the conclusion, since the cathedrals are only
several hundred years old. The study demonstrates
  (40)   dramatically what many scientists had reasoned earlier
based on information such as the fact that for glass to
have more than a negligible ability to flow, it would
have to be heated to at least 350 degrees Celsius.

The difference in thickness sometimes observed
  (45)   in antique windows probably results instead from
glass manufacturing methods. Until the nineteenth
century, the only way to make window glass was to
blow molten glass into a large globe and then flatten it
into a disk. Whirling the disk introduced ripples and
  (50)   thickened the edges. To achieve structural stability,
it would have made sense to install these panes in
such a way that the thick portions were at the bottom.
Later, glass was drawn into sheets by pulling it from
the melt on a rod, a method that made windows more
  (55)   uniform. Today, most window glass is made by
floating liquid glass on molten tin. This process makes
the surface extremely flat.    1 
 1. Which one of the following most accurately states the main point of the passage?

(A) Zanotto's research has proven that the amount of time required for viscous flow to change the thickness of medieval cathedral glass would be greater than the age of the universe.
(B) The technology of window-glass production has progressed substantially from medieval stainedglass techniques to today's production of very flat and very unifonn panes.
(C) After years of investigation motivated partly by a common misunderstanding about the structure of glass, scientists have developed ways of precisely calculating even extremely slow rates of gravity-induced flow in solids such as glass.
(D) Recent research provides evidence that although solid glass flows slightly under the influence of gravity, such flow is only one of several factors that have contributed to noticeable differences in thickness between the top and the bottom of some old windows.
(E) Contrary to a commonly held belief, noticeable differences in thickness between the top and the bottom of some old glass windows are not due to the flowing of solid glass, but probably result instead from old glassworking techniques.

2 
 2. The passage most helps to answer which one of the following questions?

(A) What is one way in which seventeenth-century windowpane manufacturing techniques differ from those commonly used in medieval times?
(B) What is one way in which nineteenth-century windowpane manufacturing techniques differ from those commonly used today?
(C) Was glass ever used in windows prior to medieval times?
(D) Are unevenly thick stained-glass windowpanes ever made of germanium oxide glass?
(E) How did there come to be impurities in medieval stained glass?

3 
 3. Which one of the following best summarizes the author's view of the results of Zanotto's study?

(A) They provide some important quantitative data to support a view that was already held by many scientists.
(B) They have stimulated important new research regarding an issue that scientists previously thought had been settled.
(C) They offer a highly plausible explanation of how a mistaken hypothesis came to be widely believed.
(D) They provide a conceptual basis for reconciling two scientific views that were previously thought to be incompatible.
(E) They suggest that neither of two hypotheses adequately explains a puzzling phenomenon.

4 
 4. The passage suggests that the atomic structure of glass is such that glass will

(A) behave as a liquid even though it has certain properties of solids
(B) be noticeably deformed by the force of its own weight over a period of a few millennia
(C) behave as a solid even when it has reached its glass transition temperature
(D) flow downward under its own weight if it is heated to its glass transition temperature
(E) stop flowing only if the atoms are arranged in a fixed crystalline structure

5 
 5. The author of the passage attributes the belief that window glass flows noticeably downward over time to the erroneous assumption that

(A) the atomic structure of solid glass is crystalline rather than amorphous
(B) the amorphous atomic structure of glass causes it to behave like a very viscous liquid even in its solid form
(C) methods of glass making in medieval times were similar to the methods used in modern times
(D) the transition temperature of the glass used in medieval windows is the same as that of the glass used in modern windows
(E) liquid glass and solid glass arc thermodynamically dissimilar

6 
 6. Which one of the following is most analogous to the persistent belief about glass described in the passage?

(A) Most people believe that the tendency of certain fabrics to become wrinkled cannot be corrected during the manufacturing process.
(B) Most people believe that certain flaws in early pottery were caused by the material used rather than the process used in manufacturing the pottery.
(C) Most people believe that inadequate knowledge of manufacturing techniques shortens the life span of major appliances.
(0) Most people believe that modern furniture made on an assembly line is inferior to individually crafted furniture.
(E) Most people believe that modern buildings are able to withstand earthquakes because they arc made from more durable materials than were older buildings.

7 
 7. The passage suggests that which one of the following statements accurately characterizes the transition temperature of glass?

(A) It is higher for medieval glass than for modern glass.
(B) It has only recently been calculated with precision.
(C) Its upper extreme is well above 350 degrees Celsius.
(B) It does not affect the tendency of some kinds of glass to flow downward.
(E) For some types of glass, it is a specific temperature well below 350 degrees Celsius.

RC Butler 2023  -  Practice Two RC Passages Everyday.   
Passage # 26 Date: 17-Feb-2023
 This question is a part of RC Butler 2023 .  Click here for Details

Source:   LSAT Official PrepTest 75   
 Difficulty Level:   650-700

SejalT · Answer

In question 6, option B talks about material used rather that the manufacturing technique? Can you please explain this?

bv8562 · Answer

Please provide the OA for question 4. Thanks!

Sajjad1994 · Answer

Explanation

6. Which one of the following is most analogous to the persistent belief about glass described in the passage?

Explanation

The question is asking for a situation similar to the mistaken belief about glass. The persistent mistaken belief was based on a misunderstanding of the structure of glass, while the real cause of thicker glass at the base of windows was the manufacturing process. The correct answer will match this logic.

A. No.  This does not match the passage. The passage does not discuss correction as an issue in the misunderstanding.

B.  Yes.   This matches the mistaken attribution of an effect to the glass itself rather than the manufacturing process.

C. No.  This does not match the passage. The passage makes no mention of a shortened life span.

D. No.  This does not match the passage. The passage does not discuss quality in relation to the mistaken belief.

E. No.  This does not match the passage. The passage does not discuss durability.

Answer: B

Sajjad1994 · Answer

Explanation

4. The passage suggests that the atomic structure of glass is such that glass will

Explanation

The correct answer will be supported by something the passage says about the atomic structure of glass. The passage notes that glass does not have a fixed atomic structure.

A. No.  This is contradicted by the passage. At the end of the first paragraph, the author asserts that glass will behave as a solid.

B. No.  This is contradicted by the passage. In the second paragraph, the author discusses Zanotto’s study results showing that it would take far more than a few millennia for glass to move in a noticeable way.

C. No.  The passage states that glass behaves as a solid when it’s cooled below the transition temperature.

D.  Yes.   In the third paragraph, the passage states that glass could have the ability to flow when raised to over 350 degrees Celsius.

E. No.  This is contradicted by the passage. In the first paragraph, the author discusses that glass does not have a fixed crystalline structure, but still behaves as a solid.

Answer: D

Utkersh · Answer

Sajjad1994 , can you please post explanations of Q5 and Q7?

Sajjad1994 · Answer

Explanation

5. The author of the passage attributes the belief that window glass flows noticeably downward over time to the erroneous assumption that

Difficulty Level:   650

Explanation

The question is asking about the reason that the author gives for people believing that glass flows noticeably downward. In the first paragraph, the author states that the mistaken belief is likely due to a misunderstanding about glass’s lack of crystalline structure.

A. No.  While the confusion is related to the lack of crystalline structure, it arises out of a knowledge that there is no crystalline structure and misunderstanding about the consequences of that fact.

B.  Yes.   The author states that the cause is likely a misunderstanding of the consequences of a lack of crystalline structure.

C. No.  The author does not discuss glassmaking methods in the first paragraph.

D. No.  The author’s discussion of transition temperatures is in a different part of the passage and is unrelated to the mistaken belief people held.

E. No.  The language in this answer choice is tempting, but the author argues that the misunderstanding stems from an assumption that liquid and solid glasses are similar rather than dissimilar.

Answer: B

Sajjad1994 · Answer

Explanation

7. The passage suggests that which one of the following statements accurately characterizes the transition temperature of glass?

Difficulty Level:   650-700

Explanation

The correct answer will be the statement best supported by the passage’s discussion of the transition temperature of glass. The passage states that this is a range of a few hundred degrees Celsius, below which glass behaves as a solid.

A. No.  The passage does not provide relative transition temperatures.

B. No.  The passage does not indicate that Zanotto calculated the temperature precisely, merely that he has calculated the time needed for a noticeable flow.

C.  Yes.   The passage states that glass would need to be heated to at least 350 degrees for any sort of noticeable flow, and given that the range is a few hundred degrees, the top end of the range would need to be a few hundred degrees above.

D. No.  This is unsupported by the passage. Glass within the transition temperature range would be able to flow downward.

E. No.  This is contradicted by the passage. The passage states that it is a range of a few hundred degrees, not a specific temperature.

Answer: C

RahulJain293 · Answer

Sajjad1994 Could you please advise on Q3?

Vandanaa · Answer

Hi Sajjad,

I understand in Q3 why A is the correct answer choice, but I am not able to wrap my head around why option E is wrong?

"E -  They suggest that neither of two hypotheses adequately explains a puzzling phenomenon. "

Vishal_Jain · Answer

Hello  Vandanaa ,
For question 3 option E is wrong because there is no two hypotheses in the passage.

There is a commonly held belief among people that glass tends to flow down because of its " Not fixed structure" thereby behaving as a liquid though it appears to be solid. --->  Hypotheses or belief

The scientists are strange about this that feel in order for glass to flow downward it must atleast be heated to "glass transition temperature" above 350 Celsius (Look lines 39 to 43). ---->  scientists objecting the belief

So, in a way Zanotto's study confirm that for glass to significantly flow downward it takes much time than few millennia. Thereby, siding with scientists or bolstering their argument through his quantitative data.

This is explains why Option A is right and Option E is wrong.

Hopefully my answer helps.

Thanks & Regards 
Vishal Jain.

siddhantvarma · Answer

Sajjad1994  Please provide OE for question 3. Thanks!

To glass researchers it seems somewhat strange that many people throug

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To glass researchers it seems somewhat strange that many people throug

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