PrepTest 124, Section 1, Question 7
Superconductors are substances that conduct electricity without resistance(55 more words not shown)
If the statements above are(10 more words not shown)
- AThe use of(6 more words not shown)
- BIf the alloys(23 more words not shown)
- CThe use of(19 more words not shown)
- DAlloys of niobium(12 more words not shown)
- ENo use of(10 more words not shown)
Reading the argument
The only possible material can't meet the temperature requirement. That leaves us stuck.
For superconductors to be economically feasible, something must superconduct above minus 148 degrees Celsius. The passage then narrows the possible materials: anything that can do that must be an alloy of niobium and germanium. But those alloys superconduct at temperatures no higher than minus 160 degrees Celsius.
Keep the negative numbers straight. Minus 160 is colder than minus 148. Even the stated upper limit for these alloys falls short of the warmer temperature we need. And we can't rescue the plan by choosing some other material, because the passage says anything meeting the required temperature would have to be one of these alloys.
What we’re looking for
The question asks what must be true if we accept those statements. We aren't being asked whether the science is correct in the real world. Within these facts, economically feasible use is impossible: the required substance cannot exist.
Working the answers
- ACorrect
Economic feasibility requires a substance that superconducts above minus 148 degrees Celsius. Only niobium-germanium alloys could qualify, and their limit is minus 160. Since the required condition cannot be met, the use of superconductors will never be economically feasible under the passage's facts.
- B
The failure of these alloys doesn't make another material available. The passage explicitly says that a substance meeting the temperature requirement must be a niobium-germanium alloy. B tries to escape the problem using an alternative the passage has ruled out.
- C
Superconducting below minus 148 doesn't solve a problem that requires superconducting above minus 148. The passage already allows superconductivity at very cold temperatures; the economic obstacle is reaching the warmer range. C doesn't satisfy that requirement and conflicts with the impossibility established by the combined facts.
- D
“No higher than minus 160” places an upper limit on the temperature. It doesn't exclude temperatures below minus 160. D turns the stated ceiling into a ban on the colder temperatures where the alloys can superconduct. That is not what the passage says.
- E
No use at all? We have only discussed using these alloys as superconductors. Perhaps they have some useful role in manufacturing a car or another product. That possibility isn't ruled out by their superconducting temperature limit. A concerns the use we investigated; E expands the conclusion to every possible use of the materials.
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