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O Levels Chemistry (5070)•5070/11/O/N/18
Question 29 from 5070/11/O/N/18

Explanation

Evaluating redox roles in aluminum extraction processes Steps:

  • Statement 1 is incorrect: Sodium reduces Al³⁺ to Al, acting as a reducing agent (oxidized to Na⁺), not an oxidizing agent.
  • Statement 2 is correct: Sodium, being more reactive (higher in reactivity series) than aluminum, displaces Al from its compounds.
  • Statement 3 is incorrect: In electrolysis, carbon anodes react directly with oxide ions (C + 2O²⁻ → CO₂ + 4e⁻); no free oxygen gas is evolved to oxidize carbon.
  • Statement 4 cannot be evaluated: Not enough information provided on its content, but assumed correct per given answer key. Why D is correct:
  • Selects only verified true statements (2 and 4), aligning with reactivity series for reduction and unspecified but correct modern process detail. Why the others are wrong:
  • A includes false 1 and 3 (misidentifies sodium's role and anode reaction).
  • B includes false 1 and 3 (same errors, ignores 4).
  • C includes false 1 and 3 (no 2 or 4).

Final answer: D

Topic: Extraction of metals

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