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Zorluk: ZorProcedural Steps

To analyze trace chemical constituents in polar ice cores without contamination, glaciologists must execute a rigorous decontamination protocol in a clean room. First, the core sections, which are retrieved from the field wrapped in polyethylene, are mechanically scraped inside a clean-air hood. Technicians use a pre-cleaned band saw to shave off the outer 15%15\% of the core's radius, which has been exposed to drilling fluids. Following this dry scraping, the core segment is subjected to a sequential washing sequence using ultra-pure water. The segment is rinsed three times in separate baths of deionized water (>18.2 MΩcm> 18.2\text{ M}\Omega\cdot\text{cm}) maintained at 1C1^\circ\text{C} to melt away another thin outer layer. Crucially, the segment must be immediately dried under a stream of high-purity nitrogen gas after the final rinse. If the drying step is omitted or delayed, the residual wash water will refreeze on the core surface, capturing ambient gases and dust from the clean room air and compromising the subsequent mass spectrometry analysis. Only after complete drying is the remaining inner core melted in a Teflon beaker under vacuum for isotopic analysis.

Based on the passage, what is the direct consequence of omitting the high-purity nitrogen gas drying step during the ice core decontamination protocol?

  1. The residual wash water will refreeze on the core surface, trapping ambient contaminants and compromising the mass spectrometry analysis.Cevap
  2. B
    The core segment will melt completely during the sequential rinse sequence, preventing subsequent melting under vacuum.
  3. C
    The drilling fluids present on the core's outer radius will seep into the inner core, ruining the isotopic analysis.
  4. D
    The inner core will fail to melt when placed in the Teflon beaker under vacuum.

Cevap

The residual wash water will refreeze on the core surface, trapping ambient contaminants and compromising the mass spectrometry analysis.
The correct option is supported by the direct statement in the text that omitting the nitrogen drying step causes residual wash water to refreeze and trap ambient contaminants, thereby compromising the mass spectrometry analysis.

Adım Adım Çözüm

1
Identify the specific step mentioned in the question (the high-purity nitrogen gas drying step).
The drying step occurs immediately after the final rinse of the sequential washing sequence.
This establishes where the step fits in the overall decontamination protocol.
2
Locate the portion of the passage describing the omission or delay of this step.
The passage states: 'If the drying step is omitted or delayed, the residual wash water will refreeze on the core surface, capturing ambient gases and dust from the clean room air and compromising the subsequent mass spectrometry analysis.'
This directly links the omission of the drying step to its specific consequence.
3
Match the consequence described in the text with the correct option.
The correct option describes the refreezing of residual wash water, trapping of ambient contaminants, and compromise of the mass spectrometry analysis.
This ensures the selected option is factually accurate according to the passage.

Anahtar Kavram

Identifying the consequences of omitting a procedural step in a process description
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