PrepTest 143

Incorrect. (Lines 9-12) The Author says that it's a "fact" that glass atoms aren't in a fixed crystal structure, and in this way liquid and solid glass are "very similar." This serves as the basis for the misunderstanding that underlies the opposing view, but they don't get this wrong—rather, they misunderstand what it means.

Correct. Question Type:
Must Be True

Strategy Overview:
Review where the Author talks about the erroneous basis for the opposing point, then find an answer reflecting it

Answer Anticipation/Relevant Lines:
When the Author of a passage notes an assumption of an opposing point, it's imperative that you understand and note it. Here, you should have noted (as we did) that the Author brings up the probable misunderstanding that led to the persistent belief that glass flows like water. This showed up starting in Line 8, and the Author in that sentence talks about a misunderstanding, which is one type of assumption.

What is that misunderstanding? It's stated that the belief formed because of a misunderstanding of "the fact" that glass atoms aren't in a fixed crystal structure. It's important to really understand this statement—that glass atoms aren't in a fixed crystal structure is a fact—it's true. So that can't be the erroneous assumption—it must be an erroneous implication of this that is the basis for the persistent (wrong) belief.

The passage then says that "[i]n this respect," solid and liquid glass are similar—i.e., they have the same unfixed crystal structure—but there's a difference in that they're not thermodynamically the same.

Let's head back to the original view to see where the mistake might be. The Author presents as a fact accepted by the common belief that glass doesn't have a fixed crystal structure. And this is true of both liquid and solid glass. Does that view treat liquid and solid glass as the same? It does—it assumes they both flow. However, the Author argues that solid glass doesn't flow like liquid glass, so the difference noted between the two must be relevant—that they don't have the same thermodynamic properties.

So, in other words, the Author must believe that the belief that window glass flows is based on the mistaken belief that it does so because it has the same unfixed crystal structure as liquid glass, when what actually matters are the thermodynamic properties. Or, the shorter version, the assumption is that if solid glass has an unfixed crystal structure, it'll flow.

Answer Explanation:
(Lines 7-13; Lines 16-19) The Author draws a line between the atomic structure of glass and its thermodynamic properties. She attributes the wrong belief to a focus on the atomic structure of liquid and solid glass being the same, which is referred to as "amorphous" in Lines 17-18, and then assuming this means that they both flow. However, in reality, the thermodynamic properties are what's important, and they're different between solid and liquid glass. This answer thus reflects the Author's view on what the common belief gets wrong, so it's the correct answer.

Key Takeaway:
This question can seem very science-y, but, in reality, it ends up being about comparisons. The Author brings up a way that solid and liquid glass are similar and different. The opposing point treats them as similar. As such, they must be assuming that the similarity is relevant and the dissimilarity isn't. That's a pretty common comparison-based argument that we would see in a Strengthen or Weaken question! Focusing on that common logical element would have made this question a lot easier.

Incorrect. (Paragraph 4) The discussion of glass-making methods in the passage doesn't show up until Paragraph 4, and the discussion of what the opposing point gets wrong is in Paragraph 1. The two aren't tied together at all.

Incorrect. (Lines 35-36) The closest the passage gets to discussing this is when it brings up the impurities that might affect the medieval stained glass. However, it doesn't note that these same impurities aren't present in modern windows, nor does it offer any indication that this serves as a basis for the persistent myth.

Incorrect. (Lines 12-13) The Author notes that solid and liquid glass are thermodynamically dissimilar, so it's not an erroneous assumption that she points out in the opposing point.