Blast Furnace Iron Extraction Process

Steps:

• Recall that hot air is blasted into the furnace to react with coke (carbon), forming CO for reducing iron oxide: C + 1/2 O₂ → CO.
• Note limestone (CaCO₃) thermally decomposes to CaO + CO₂, where CaO acts as a base to remove SiO₂ impurities as slag.
• Determine layer order: molten iron (density ~7 g/cm³) sinks below less dense slag (~3 g/cm³).
• Classify SiO₂: it behaves as an acidic oxide, reacting with basic CaO.

Why A is correct:

• Air supplies oxygen that reacts with carbon per the equation 2C + O₂ → 2CO, generating the reducing gas essential for iron oxide reduction.

Why the others are wrong:

• B: Molten iron is denser than slag, so it forms the bottom layer with slag floating above.
• C: Decomposition of limestone follows CaCO₃ → CaO + CO₂; the statement omits CO₂, making it incomplete.
• D: SiO₂ is an acidic oxide that reacts with basic CaO to form slag, not a basic oxide.

Final answer: A