Among the reactions (a) - (d), the reaction(s) that does/do not occur in the blast furnace during the extraction of iron is/are :
(a) CaO + SiO₂ → CaSiO₃
(b) 3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂
(c) FeO + SiO₂ → FeSiO₃
(d) FeO → Fe + 1/2O₂

Solution

Chemistry ma’am · 2 steps

In the blast furnace iron oxides are reduced by CO, and only CaO is used to carry silica away as slag.

1. What the furnace does. Coke burns to give CO, and CO (with carbon lower down) pulls oxygen off the iron oxides step by step. Limestone gives CaO, which removes the silica impurity as slag.

   Reaction	Occurs in the blast furnace?	Why
   (a) CaO + SiO₂ → CaSiO₃	Yes	Slag formation. Calcium silicate floats on the molten iron and removes silica.
   (b) 3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂	Yes	First reduction step, in the cooler upper zone (about 500 to 800 K).
   (c) FeO + SiO₂ → FeSiO₃	No	FeO is reduced to iron here, not slagged. Iron silicate slag forms in copper extraction, where iron is the impurity.
   (d) FeO → Fe + 1/2 O₂	No	FeO does not decompose on heating alone. It is reduced as FeO + CO → Fe + CO₂.

2. So. Reactions (c) and (d) do not take place in the blast furnace, which is option (b).

The idea to keep. Blast furnace: iron oxides lose oxygen to CO, never by heating alone, and the flux is CaO giving CaSiO₃. FeSiO₃ slag belongs to copper extraction, where iron is the impurity.

Answer from the NTA final answer key. Solution by PrepWiser.