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Difficulty: HardMust Be True Questions

According to the planetary geology archives:

- Every meteorite classified as a Type C chondrite contains elevated levels of iridium.
- Any meteorite containing elevated levels of iridium is designated as a Class-1 research priority by the Astromaterials Board.
- No meteorite recovered from the Antarctic glacial surface is designated as a Class-1 research priority unless it is a newly discovered fragment that has not been previously cataloged.
- Some meteorites classified as Type C chondrites were recovered from the Antarctic glacial surface, and most of these are exceptionally well-preserved.

Based on the information provided, which of the following statements must be true? (Select all that apply.)

  1. Every Type C chondrite recovered from the Antarctic glacial surface is a newly discovered fragment.Answer
  2. At least some exceptionally well-preserved meteorites contain elevated levels of iridium.Answer
  3. C
    Any meteorite recovered from the Antarctic glacial surface that contains elevated levels of iridium is exceptionally well-preserved.
  4. D
    All newly discovered fragments designated as Class-1 research priorities are Type C chondrites.
  5. E
    Most newly discovered fragments recovered from the Antarctic glacial surface contain elevated levels of iridium.

Answer

The correct statements are that every Type C chondrite recovered from the Antarctic glacial surface is a newly discovered fragment, and that at least some exceptionally well-preserved meteorites contain elevated levels of iridium.
Based on the rules, any Type C chondrite is a Class-1 priority. Therefore, any Type C chondrite from Antarctica is both from Antarctica and a Class-1 priority, which means it must be a newly discovered fragment. Additionally, because some Type C chondrites from Antarctica exist, and most of them are well-preserved, there is at least one well-preserved Type C chondrite. Since it is Type C, it must contain elevated levels of iridium.

Step-by-Step Solution

1
Map the universal conditional statements.
Type C -> Iridium -> Class-1 Priority. (Antarctic AND Class-1) -> Newly Discovered.
This establishes the strict logical chains required to evaluate absolute statements.
2
Analyze the quantified statements ('some' and 'most').
There exists a group of meteorites that are Type C and Antarctic. Most of this specific group are well-preserved.
Quantifiers provide the existential facts that interact with the universal rules.
3
Combine the existential facts with the universal chains.
The (Type C + Antarctic) meteorites must be Class-1 (since they are Type C). Because they are (Class-1 + Antarctic), they must be newly discovered. Thus, all (Type C + Antarctic) are newly discovered.
This guarantees the truth of the statement regarding Type C chondrites from Antarctica.
4
Derive inferences from the 'most' statement.
Since 'most' of the (Type C + Antarctic) group are well-preserved, at least one such meteorite exists. Because this meteorite is Type C, it contains iridium. Therefore, some well-preserved meteorites contain iridium.
This guarantees the truth of the statement regarding well-preserved meteorites.

Key Concept

Chaining Conditional Statements and Quantifier Logic
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