Passage
A mineral is a naturally occurring solid formed by inorganic processes. Since the internal structure and chemical composition of a mineral are difficult to determine without the aid of sophisticated tests and apparatus, the more easily recognized physical properties are used in identification.
Most people think of a crystal as a rare commodity, when in fact most inorganic solid obJects are composed of crystals. The reason for this misconception is that most crystals do not exhibit their crystal form: the external form of a mineral that reflects the orderly internal arrangement of its atoms. Whenever a mineral forms without space restrictions, individual crystals with well-formed crystal faces will develop Some crystals, such as those of the mineral quartz, have a very distinctive crystal form that can be helpful in identification. However, most of the time, crystal growth is interrupted because of competition for space, resulting in an intergrown mass of crystals, none of which exhibits crystal form.
Although color is an obvious feature of a mineral, it is often ,an unreliable diagnostic property. Slight impurities in the common mineral quartz, for example, give it a variety of colors, including pink, purple (amethyst), white, and even black. When a mineral, such as quartz, exhibits a variety of colors, it is said to possess exotic coloration. Exotic coloration is usually caused by the inclusion of impurities, such as foreign ions, in the crystalline structure Other minerals for example, sulfur, which is yellow, and malachite, which is bright green-are said to have inherent coloration because their color is a consequence of their chemical makeup and does not vary significantly.
Streak is the color of a mineral in its powdered form and is obtained by rubbing a mineral across a plate of unglazed porcelain. Whereas the color of a mineral often varies from sample to sample, the streak usually does not and is therefore the more reliable property.
Luster is the appearance or quality of light reflected from the surface of a mineral Minerals that have the appearance of metals, regardless of color, are said to have a metallic luster Minerals with a nonmetallic luster are described by various adjectives, including vitreous (glassy), pearly, silky, resinous, and earthy (dull).
One of the most useful diagnostic properties of a mineral is hardness, the resistance of a mineral to abrasion or scratching. This property is determined by rubbing a mineral of unknown hardness against one of known hardness, or vice versa A numerical value can be obtained by using Mohs'scale of hardness, which consists of ten minerals arranged in order from talc, the softest, at number one, to diamond, the hardest, at number ten. Any mineral of unknown hardness can be compared with these or with other objects of known hardness. For example, a fingernail has a hardness of 2.5, a copper penny 5, and a piece of glass 5.5. The mineral gypsum, which has a hardness of two, can be easily scratched with your fingernail. On the other hand, the mineral calcite, which has a hardness of three, will scratch your fingernail but will not scratch glass Quartz, the hardest of the common minerals, will scratch a glass plate.
The tendency of a mineral to break along planes of weak bonding is called cleavage. Minerals that possess cleavage are identified by the smooth, flat surfaces produced when the mineral is broken. The simplest type of cleavage is exhibited by the micas. Because the micas have excellent cleavage in one direction, they break to form thin, flat sheets. Some minerals have several cleavage planes, which produce smooth surfaces when broken, while others exhibit poor cleavage, and still others exhibit no cleavage at all. When minerals break evenly in more than one direction, cleavage is described by the number of planes exhibited and the angles at which they meet. Cleavage should not be confused with crystal form. When a mineral exhibits cleavage, it will break into pieces that have the same configuration as the original sample does. By contrast, quartz crystals do not have cleavage, and if broken, would shatter into shapes that do not resemble each other or the original crystals. Minerals that do not exhibit cleavage are said to fracture when broken. Some break into pieces with smooth curved surfaces resembling broken glass. Others break into splinters or fibers, but most fracture irregularly.
Video Script
Hi everyone! Welcome to TOEFL Reading. Today, let's work together to answer a whole set of official TOEFL Reading questions. This is an older version, but since ETS has been recycling their material, it’s still very valuable to go through.
First off, it’s important to note that the official answer by ETS for question 12 is actually incorrect. We'll show you what the correct answer should be.
The passage we’re focusing on is about the Physical Properties of Minerals. While the passage itself is straightforward, some inference questions can be challenging. As Dr. Byrnes emphasizes, when evaluating choices, don’t just grasp the content—pay attention to how they are worded. Often, certain words can make an option incorrect without even understanding the full content of the choice. This is a common trick that the ETS uses repeatedly to make certain choices false. This also applies to TOEFL listening questions as well. You can quickly eliminate those choices. This is a critical skill for solving any reading comprehension questions, such as information, inference, and summary questions. In the recently published summary video, Dr. Byrnes covered all the elimination clues you can use by just paying attention to how the choices are worded without reading the passage. Don’t forget to watch it if you haven’t done so yet. Paying attention to these clue words will train you to develop a feel for the correct answers.
Let's briefly skim the passage. The first paragraph provides a definition of minerals. Paragraph 2 discusses misconceptions about crystals, and then it talks about color, streak, luster, hardness, and cleavage.
OK, let's move on to the questions.
1. The word "apparatus' in the passage is closest in meaning to
A. equipment
B. procedures
C. experiments
D. laboratories
“Apparatus” means tools, so A. equipment is best.
2. According to paragraph 2, which of the following is a mistaken belief that people have about crystals? (hardest)
A. Crystals always have a well-formed shape
B. Minerals are generally composed of crystals.
C. The atoms of a crystal have an orderly arrangement.
D. Crystals are always solid and inorganic.
The key to answering this question is understanding what people commonly believe about crystals versus what is actually true.
Paragraph 2 tells us:
Most crystals don't actually show their crystal shape on the outside.
The inside of a crystal is always orderly, but the outside might not look like it.
Crystals only form perfect shapes when they have enough space to grow.
When crystals grow close together, they don't form perfect shapes.
The mistake people often make is thinking that all crystals must have a perfect, well-formed shape to be considered crystals. In reality, many crystals don't look like the perfect shapes we imagine.
Looking at the answer choices:
A. This is the correct answer. People wrongly believe crystals always have a well-formed shape, but that's not true.
B. This is actually correct, not a mistaken belief.
C. This is also correct. Crystals do have an orderly arrangement of atoms.
D. This is incorrect, but it's not the common mistaken belief the question is asking about.
The word "always" in option A is a good clue, as it points to an absolute statement that's likely to be false.
So, the answer is A: The mistaken belief is that crystals always have a well-formed shape.
3. Why is the color of a mineral an "an unreliable diagnostic property"?
A. Different minerals can have the same color
B. The color is often not a result of the chemical makeup that determines the identity of the mineral.
C. The color of a mineral cannot be predicted from knowing what foreign ions it contains.
D. No two pieces of the same mineral have exactly the same color.
Explanation
The question asks why the color of a mineral is considered "an unreliable diagnostic property." Here's the relevant information from the passage:
Color is an obvious feature but often unreliable for identifying minerals.
Slight impurities in minerals like quartz can cause a variety of colors (e.g., pink, purple, white, black).
This variety of colors due to impurities is called exotic coloration.
Some minerals, like sulfur (yellow) and malachite (green), have inherent coloration because their color comes from their chemical makeup and doesn't vary much.
The reason color is unreliable is that the same mineral can have different colors due to impurities. However, some minerals have consistent colors due to their chemical makeup.
Now, let's look at the answer choices:
A. This is not the reason. Different minerals having the same color is not why color is unreliable. Many people chose Option A. In fact, option A is a true statement, but it does not address the reason for the unreliability of color in identifying minerals, which is primarily due to the influence of impurities on the color of the same mine ral.
B. This is correct. The color can be due to impurities, not the mineral's chemical makeup.
C. This misses the point. It's not about predicting color from foreign ions.
D. This is wrong. "No two pieces" is an absolute statement, and sulfur and malachite are counterexamples.
So, the answer is B: The color is often not a result of the chemical makeup that determines the identity of the mineral.
4. The word "inherent" in the passage is closest in meaning to
A. bright
B. essential
C. superficial
D. transparent
“inherent” meas intrinsic, deep-rooted, essential, fundamental. So Answer is B
5. According to paragraph 3, how do different samples of the same mineral come to exhibit a variety of colors?
A. The samples have different crystalline structures.
B. The samples contain different varieties of quartz.
C. The samples differ in the impurities they contain
D. The samples were formed in different exotic conditions.
5 basically asks the same idea as question 3 but much straightforward.
Answer: C
Question 6. Which of the following can be inferred about streak from paragraph 4?
A. When a sample of a mineral is rubbed on unglazed porcelain, the color of the streak is usually the same as the color of the sample.
B. In most cases, different samples of a mineral produce streaks that are all of the same color even though the samples themselves are of different colors.
C. When a streak is made, the impurities in the mineral are removed and the true color of the mineral is revealed
D. Streak color is reliable for identifying minerals because a given mineral sample always yields the same color of streak each time it is rubbed
The question asks what can be inferred about streak from paragraph 4. Here's the relevant information from the passage:
Streak is the color of a mineral in its powdered form.
It is obtained by rubbing a mineral across a plate of unglazed porcelain.
The color of a mineral often varies from sample to sample.
The streak usually does not vary and is therefore a more reliable property.
From this, we can infer that even though the color of a mineral can change from sample to sample, the streak color remains consistent.
Now, let's look at the answer choices:
A. This is a trap. The streak color can be different from the color of the sample.
B. This is true. Different samples of a mineral produce streaks that are all the same color, even if the samples themselves are different colors.
C. This is not mentioned. The passage doesn't say anything about impurities being removed to reveal the true color.
D. This is somewhat relevant but not exactly the point made in the passage. Additionally, the word "always" makes this claim questionable.
So, the answer is B: In most cases, different samples of a mineral produce streaks that are all of the same color even though the samples themselves are of different colors.
Answer: B
Question 7. The discussion of Mohs' scale in paragraph 6 answers which of the following questions?
A. How was it determined that Mohs' scale would have ten minerals?
B. Is quartz one of the ten minerals that determine Mohs' scale?
C. Does Mohs' scale apply to materials other than minerals?
D. What mineral is harder than quartz and softer than diamond?
Explanation
The question asks which of the following questions is answered by the discussion of Mohs' scale in paragraph 6.
Key information from the paragraph:
Mohs' scale consists of ten minerals arranged from softest to hardest.
It's used to compare minerals of unknown hardness with those of known hardness.
The paragraph mentions non-mineral objects like fingernails, copper pennies, and glass, giving their hardness values on the Mohs scale.
fingernails, copper pennies, and glass are non-minerals, but have Mohs values
Now, let's analyze each option:
A. This is not mentioned in the paragraph. There's no discussion about how the number of minerals on the scale was determined.
B. While quartz is mentioned, the paragraph doesn't explicitly state that it's one of the ten minerals on Mohs' scale.
C. This is correct. The paragraph clearly shows that Mohs' scale applies to materials other than minerals by giving hardness values for fingernails, copper pennies, and glass.
D. The paragraph doesn't provide information about minerals between quartz and diamond on the scale.
Therefore, the correct answer is C: Does Mohs' scale apply to materials other than minerals?
The paragraph demonstrates that Mohs' scale can be used to measure the hardness of non-mineral materials, answering this question affirmatively.
Question 8. It can be inferred from paragraph 6 that the mineral quartz (easy)
A. has no fixed degree of hardness
B. might scratch the surface of a diamond
C. is harder than calcite
D. has atoms that are weakly bonded to each other
Explanation
The question asks what can be inferred about quartz from paragraph 6.
Key information from the paragraph:
Calcite has a hardness of 3 on Mohs' scale.
Calcite can scratch a fingernail (hardness 2.5) but not glass (hardness 5.5).
Quartz is described as "the hardest of the common minerals."
Quartz can scratch glass.
Analysis of the options:
A. Incorrect. The passage doesn't suggest that quartz has no fixed hardness.
B. Incorrect. While quartz is hard, there's no information suggesting it could scratch a diamond (the hardest mineral on the scale).
C. Correct. We can infer this because:
Calcite (hardness 3) cannot scratch glass (hardness 5.5).
Quartz can scratch glass.
Therefore, quartz must be harder than both calcite and glass. Thus, of course, it is harder than calcite.
D. Incorrect. The passage doesn't provide information about the atomic bonding in quartz.
Therefore, the correct answer is C: Quartz is harder than calcite.
9. The word "configuration" in the passage is closest in meaning to (medium)
A. Effect
B. Range
C. Transformation
D. Form
Configuration is made of “con” which means together, and “figure” which means shape. so it means putting shapes together to form something.
Answer: D
Question 10. According to paragraph 7, which of the following is true of the cleavage of micas?
A. Micas are the only minerals to break along planes of weak bonding
B. Micas exhibit poor cleavage because they tend to break unevenly.
C. Micas break in one direction, forming thin sheets with smooth surfaces
D. Micas break in several directions, forming a number of angles and planes.
Explanation
The question asks about the cleavage of micas according to paragraph 7.
K ey information from the paragraph:
Cleavage is the tendency of a mineral to break along planes of weak bonding.
Micas exhibit the simplest type of cleavage.
Micas have excellent cleavage in one direction.
When broken, micas form thin, flat sheets.
Now, let's analyze each option:
A. Incorrect. The passage doesn't state that micas are the only minerals with this property.
B. Incorrect. This contradicts the passage, which states that micas have excellent cleavage, not poor cleavage.
C. Correct. This accurately summarizes the information given: micas break in one direction (excellent cleavage in one direction) and form thin, flat sheets.
D. Incorrect. The passage specifically states that micas cleave in one direction, not several.
Therefore, the correct answer is C: Micas break in one direction, forming thin sheets with smooth surfaces.
This answer directly aligns with the information provided in the paragraph about mica's cleavage properties.
Question 11. According to paragraph 7, minerals that exhibit no cleavage
A. break evenly in more than one direction
B. have no crystalline form
C. shatter in pieces of various shapes and sizes
D. have surfaces that resemble broken glass
Explanation
The question asks about minerals that exhibit no cleavage, according to paragraph 7.
Key information from the paragraph:
Some minerals exhibit no cleavage at all.
Minerals that do not exhibit cleavage are said to fracture when broken.
Quartz is given as an example of a mineral without cleavage.
The paragraph states about quartz: "if broken, would shatter into shapes that do not resemble each other or the original crystals."
Now, let's analyze each option:
A. Incorrect. This describes minerals with multiple cleavage planes, not those without cleavage.
B. Incorrect. The paragraph doesn't suggest that minerals without cleavage lack crystalline form.
C. Correct. This aligns with the description of quartz, which shatters into various shapes when broken.
D. Partially correct but incomplete. While some minerals without cleavage might break with smooth curved surfaces like glass, this is not true for all minerals without cleavage.
Therefore, the correct answer is C: Minerals that exhibit no cleavage shatter in pieces of various shapes and sizes.
This answer best matches the description in the paragraph, particularly the example of quartz shattering into shapes that don't resemble each other or the original crystal.:
Question 12. Why does the author warn Cleavage should not be confused with crystal form?
A. Because most people have the mistaken belief that the surfaces of crystals are planes of crystal cleavage
B. Because the author's characterization of cleavage in terms of smooth planes and the angles between them could easily be mistaken for a description of crystal form
C. To make the point that crystal form and cleavage are the same property only in the simplest cases of cleavage, such as mica
D. To introduce a discussion of minerals the have cleavage but not crystal form
Explanation
The question asks why the author warns that "Cleavage should not be confused with crystal form."
Key information from the paragraph:
Cleavage refers to the tendency of a mineral to break along planes of weak bonding, producing smooth, flat surfaces.
Crystal form refers to the external shape of a crystal, which is determined by the arrangement of its atoms.
The author emphasizes that cleavage and crystal form are two different properties.
Now, let's analyze each option:
A. Incorrect. The passage does not mention a common mistaken belief about the surfaces of crystals being planes of crystal cleavage.
B. Correct. The author's description of cleavage involving smooth planes and angles could indeed be mistaken for a description of crystal form. The warning is to clarify that these are distinct properties.
C. Incorrect. The author does not suggest that crystal form and cleavage are the same property, even in the simplest cases like mica.
D. Incorrect. The warning is not used to introduce a discussion of minerals with cleavage but not crystal form; it is to clarify the distinction between the two properties.
Therefore, the correct answer is B: Because the author's characterization of cleavage in terms of smooth planes and the angles between them could easily be mistaken for a description of crystal form.
This answer best explains why the author would caution readers not to confuse cleavage with crystal form, emphasizing the need to distinguish between these two different properties.
CAUTION
A Chinese website says the answer is A, but A cannot be inferred since there is no mention or hint of “most people have the mistaken belief that the surfaces of crystals are planes of crystal cleavage.” The context of the warning comes after describing cleavage in detail, suggesting it's meant to clarify the distinction between cleavage (how a mineral breaks) and crystal form (the external shape of the crystal). B clearly explain this context.
Answer: B
13. Look at the four squares【】that indicate where the following sentence could be added to the passage (medium)
Each mineral has an orderly arrangement of atoms (crystalline structure) and a definite chemical composition that give it a unique set of physical properties.
Where would the sentence best fit? Click on a square【】to add the sentence to the passage.
A mineral is a naturally occurring solid formed by inorganic processes. 【A】Since the internal structure and chemical composition of a mineral are difficult to determine without the aid of sophisticated tests and apparatus., the more easily recognized physical properties are used in identification【B】Most people think of a crystal as a rare commodity, when in fact most inorganic solid objects are composed of crystals【C】The reason for this misconception is that most crystals do not exhibit their crystal form: the external form of a mineral that reflects the orderly internal arrangement of its atoms【D】
Explanation:
The target sentence introduces what minerals have: an orderly arrangement of atoms and a definite chemical composition, which together provide a unique set of physical properties. From this, we can infer that the sentence should come after the definition of a mineral, which is what a mineral is.
2. Mineral has an orderly arrangement of atoms and specific chemical composition
3. Since tools are needed to determine the atomic arrangement and chemical composition…
Sentence A talks about "the chemical structure," and because of "the," we know that the chemical structure must have been mentioned earlier. In fact, the target sentence introduces the concept of chemical structure, so it should come before A..
Answer: A
14. Directions: An introductory sentence for a brief summary of the passage is provided below Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it.
Minerals have a number of physical properties, some of which are useful for mineral identification.
Answer Choices
A. Most minerals show a characteristic crystal form that results from the way their atoms are arranged in the crystal structure
B. Luster is a good guide to the identity of glassy and metallic minerals, but not those that have dull or earthy appearance
C. Some minerals characteristically split along one or more smooth planes of cleavage while others typically fracture unevenly
D. For many minerals, the streak formed by a rubbing a mineral sample on unglazed porcelain is a more reliable guide for identification that the color of the sample
E. The relative hardness of a mineral as determined by Mohs' scale is very useful for identifying a mineral sample
F. Quartz has a characteristic crystal form, but no cleavage and its color varies widely from sample to sample, all of which make it a typical mineral
Explanation
this is the introductory sentence "Minerals have a number of physical properties, some of which are useful for mineral identification," this is a summary of summary sentences, and we need to choose options that highlight different physical properties of minerals that aid in their identification such as cleavage, streak, and hardness
A is false. Most minerals do not show a characteristic crystal form
B is false. According to the passage, minerals that have dull or earthy appearance can be identified by various adjectives. Even without the passage, we can tell that B is not a good choice since it does not support the introductory sentence. The introductory sentence highlights useful properties for identifying minerals, but B focuses on a property that is not always useful for identification. Therefore, B should be eliminated.
C. Some minerals characteristically split along one or more smooth planes of cleavage while others typically fracture unevenly.
This option discusses cleavage, a physical property that helps in identifying minerals.
D. For many minerals, the streak formed by rubbing a mineral sample on unglazed porcelain is a more reliable guide for identification than the color of the sample.
This option highlights the streak, another useful physical property for mineral identification.
E. The relative hardness of a mineral as determined by Mohs' scale is very useful for identifying a mineral sample.This option emphasizes hardness, a key physical property used in mineral identification.
F is false. Quartz cannot be a typical mineral since according to the passage, most minerals do not show a crystal form.
Answer: CDE
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