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Difficulty: MediumParaphrased Fact Recognition

Read the passage below:

To safeguard steel vessel hulls from galvanic deterioration in saltwater environments, marine technicians attach sacrificial zinc anodes along the submerged hull surface. Because zinc possesses a lower electrochemical potential than structural steel, the seawater electrolyte causes the zinc to corrode preferentially. As the zinc oxidizes and sheds electrons, it maintains a protective electrical current that shields the surrounding ferrous metal from rusting. However, if technicians mistakenly apply marine bottom paint over these anodes during scheduled maintenance, the coating insulates the zinc from the surrounding seawater, completely halting the galvanic current and accelerating hull degradation.

According to the passage, why does painting over sacrificial anodes harm a vessel's hull?

  1. A
    It causes structural steel to corrode preferentially while zinc sheds electrons directly into the paint layer.
  2. B
    It elevates the electrochemical potential of the ferrous metal above that of the surrounding saltwater.
  3. It creates an insulating barrier that prevents direct contact with seawater, disabling the galvanic protective circuit.Answer
  4. D
    It traps corrosive moisture underneath the coating, causing rapid blister cracking across the keel plates.

Answer

Painting over the anodes creates an insulating barrier that prevents direct contact with seawater, disabling the galvanic protective circuit.
The passage directly explains that marine paint acts as an insulator separating the zinc anodes from seawater, which halts the galvanic current protecting the steel hull. The correct option accurately rephrases this cause-and-effect relationship without using verbatim text.

Step-by-Step Solution

1
Locate the detail addressing what happens when paint is applied over the anodes.
Identified the sentence: '...if technicians mistakenly apply marine bottom paint over these anodes during scheduled maintenance, the coating insulates the zinc from the surrounding seawater, completely halting the galvanic current and accelerating hull degradation.'
The question asks specifically for the mechanism by which painting over sacrificial anodes damages the hull.
2
Map the identified factual detail to synonymous paraphrasing.
'Insulates the zinc from the surrounding seawater' corresponds to 'prevents direct contact with seawater', and 'halting the galvanic current' corresponds to 'disabling the galvanic protective circuit'.
Paraphrased fact recognition requires matching restructured syntax and synonyms to explicit text evidence.
3
Evaluate the answer choices to filter out verbatim traps and unsupported claims.
The statement describing the barrier effect and disabled galvanic circuit is the only accurately supported paraphrase.
Other choices distort explicit relationships, scramble verbatim keywords, or introduce external technical concepts.

Key Concept

Paraphrased Fact Recognition
Estimated Time:1m 0s
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Paraphrased Fact Recognition

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