Generated by claude-sonnet-4-6 · 2026-06-15 06:47 · grounding rag
Model Answer
(B) When it is heated with iron (III) oxide, molten iron is obtained.
The reaction is: $\text{Fe}_2\text{O}_3 + 2\text{Al} \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}$ (molten). This highly exothermic displacement reaction produces molten iron used to join railway tracks.
Source: Chapter 3, Section 3.2.4 (Reactivity Series / displacement reactions)
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Explanation
- Option (B) is correct because aluminium, being more reactive than iron, displaces iron from Fe₂O₃ in a highly exothermic thermite reaction, producing molten iron that fills the gap between railway tracks and solidifies to join them.
- Option (A) is partially true but incomplete — it doesn't explain what the reaction produces.
- Option (C) is wrong: molten Al₂O₃ is a by-product, not the substance that joins tracks.
- Option (D) is wrong: no iron-aluminium alloy is formed; pure molten iron is produced.
- Examiners expect you to pick the most complete and accurate statement — that is (B).