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Difficulty: MediumParaphrased Fact Recognition

In marine engineering, bronze propellers attached to steel hulls create an electrochemical circuit that accelerates the corrosion of the hull when immersed in saltwater. To mitigate this galvanic degradation, shipwrights affix sacrificial zinc anodes directly adjacent to the propeller shaft. Because zinc possesses a lower electrochemical potential than both steel and bronze, the electrolytic reaction preferentially oxidizes the zinc blocks while leaving the surrounding structural steel intact. Over time, these zinc attachments dissolve entirely and must be replaced during scheduled drydock maintenance to ensure ongoing hull preservation.

According to the passage, how do zinc anodes safeguard the steel structure of a vessel?

  1. A
    They eliminate the electrochemical circuit by separating the bronze propeller from the saltwater.
  2. They degrade in place of the hull metal because they react more readily in the marine environment.Answer
  3. C
    They absorb electrical currents discharged when the structural steel oxidizes during operation.
  4. D
    They permanently coat the entire submerged surface of the hull to prevent contact with seawater.

Answer

Zinc anodes protect the vessel because they degrade in place of the hull metal due to reacting more readily in the marine environment.
The passage states that because zinc has a lower electrochemical potential, the electrolytic reaction preferentially oxidizes the zinc blocks while leaving the structural steel intact. The correct option accurately paraphrases this fact by explaining that zinc degrades instead of the hull metal because it reacts more readily in the seawater environment.

Step-by-Step Solution

1
Identify the core inquiry in the question stem.
The stem asks for the factual mechanism by which zinc anodes protect the ship's steel hull.
Clarifying the specific detail required prevents confusion with peripheral context.
2
Locate the supporting detail within the passage.
The passage states that zinc has a lower electrochemical potential than steel and bronze, causing the electrolytic reaction to preferentially oxidize the zinc blocks while leaving the steel intact.
Direct text retrieval provides the factual baseline that must be matched.
3
Evaluate the answer choices for an accurate paraphrase without verbatim traps or inverted relationships.
The statement that zinc degrades in place of the hull metal because it reacts more readily in the marine environment successfully restates the concept of preferential oxidation through synonym substitution and structural rephrasing.
Standard paraphrasing tests recognition of underlying meaning rather than matching identical surface words.

Key Concept

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

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