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Difficulty: Very hardTransitions: Cause and Effect

In the cold interstellar medium, gaseous carbon monoxide readily condenses onto cosmic dust grains, forming thick icy mantles. These icy layers act as cosmic catalysts, allowing hydrogen atoms to tunnel through activation barriers and react with the trapped carbon monoxide molecules. Complex organic molecules like methanol, __________, are synthesized in environments far too cold for traditional gas-phase chemistry to occur.

Which choice completes the text with the most logical transition?

  1. consequentlyAnswer
  2. B
    conversely
  3. C
    furthermore
  4. D
    meanwhile

Answer

consequently
The correct answer is the option that uses 'consequently'. The passage establishes that icy mantles on cosmic dust grains act as catalysts, enabling hydrogen atoms to react with carbon monoxide. The synthesis of complex organic molecules like methanol in these cold environments is the direct result of these catalyzed reactions. Therefore, a cause-and-effect transition is required, and 'consequently' fits this logical relationship perfectly.

Step-by-Step Solution

1
Analyze the relationship between the sentences.
The first two sentences explain how cosmic dust grains with icy mantles act as catalysts, enabling hydrogen and carbon monoxide to react. The final sentence states that complex organic molecules like methanol are synthesized in these cold environments.
To determine the correct transition, we must identify the logical connection between the catalysis/reaction process and the synthesis of methanol.
2
Identify the logical link.
The synthesis of complex molecules in these cold environments is the direct outcome of the catalysis process described. Thus, the relationship is cause-and-effect.
Choosing a transition that reflects this logical connection is necessary for the text to be coherent.
3
Evaluate the choices based on the logical link.
The transition 'consequently' correctly signals a cause-and-effect relationship. Other options like 'conversely' (contrast), 'furthermore' (addition), and 'meanwhile' (simultaneous occurrence) do not capture this causal link.
This confirms the correct transition word to complete the text.

Key Concept

Transitions: Cause and Effect
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Topics

Transitions: Cause and Effect

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