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ACT Assessment Sample Question
Answer Key and Question Explanations

Set 4: Reading

1. The best answer is C. It is supported directly by lines 5154. The passage suggests that escaping methane affects how reflective Charon is, not its setting, which rules out D. B is eliminated by understanding that stellar occultations (line 60) refers to eclipses. A is an inappropriate choice because it relates to the number of eclipses (where, from the surface of Pluto, Charon disappears from view) occurring in a short period of time and is unrelated to why Charon never sets.

2. The best answer is G. The answer is supported by lines 3233, which establish the uniqueness of Charon and Pluto's mutual tidal coupling. No such statement is made about frequency of eclipses (F), synchronous rotation (H), or axial tilt (J), so these choices must be ruled unacceptable.

3. The best answer is C. The point of the first paragraph is how huge Charon appears in Pluto's sky. That it is unusually large rules out A: it occupies a relatively much larger portion of the sky than does Earth's moon. The first paragraph does not compare Pluto and Charon, which makes B an incorrect choice, and neither does the first paragraph compare the size of Earth to Pluto, which eliminates D as a possible choice.

4. The best answer is F. The Sun's corona is defined in lines 8083. Options II and III refer to the preceding sentence and have to do with how Charon might be illuminated during an eclipse by reflected light from Pluto and there is nothing in the passage to suggest that the Sun's corona is comprised of reflected light. This information rules out G, H, and J as acceptable answers.

5. The best answer is D. Lines 6769 state that "Because of Pluto's axial tilt and Charon's position over Pluto's equator, the pair go for almost 120 years without their shadows ever falling upon one another." This information establishes options I and III as correct. Option II, which refers to escaping methane, has no relation to eclipse frenzy.

6. The best answer is J. Support for the answer is to be found in lines 4445, which state that "Missing too from Charon is the methane frost which partially covers Pluto." There is no comparison made about escaping methane on Pluto and Charon, so no evidence exists to support A as a choice. Line 46 refers to Charon's "weaker gravity," which means the gravity is noticeable; this rules out G. We know from lines 3637 that Charon has an "uneven, cratered landscape," which rules out H.

7. The best answer is A. Lines 810 tell us that Charon takes up 4 degrees of Pluto's sky and is eight times as wide as our Moon appears from Earth. The relatively simple math produces A as the only possible choice.

8. The best answer is G. The information necessary to see that options I and II are correct is clearly stated in lines 4549. Axial tilt is referred to later (line 67) and has nothing to do with methane ice evaporation. This fact rules out H and J. F is only a partial answer, given the information cited in lines 4549.

9. The best answer is C. Support for the answer can be found in lines 1619. The passage makes no mention of axial tilt as a feature shared by satellites, which rules out A. The distance of major satellites and/or planets from one another is not taken up in those lines, or anywhere in the passage, which rules out B. The next to last paragraph makes it clear the "eclipse frenzy" is rare, so that would not be something major satellites had in common, which rules out D as a plausible choice.

10. The best answer is G. Support for the answer can be found in lines 7375. No mention is made of the discovery of the synchronous rotation of satellites anywhere in the passage; this eliminates F as a plausible choice. The passage makes clear that our Moon is not identical to Charon, which rules out H as a choice. No mention is made of a demonstration of tidal coupling by Earth and its Moon occurring at the same time or in any way relating to the discovery of Charon, which makes J an incorrect choice.

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