The following reaction occurs in the Blast Furnace where iron ore is reduced to iron metal: Fe2O3(s) + 3CO(g) Fe(l) +…

Step 1 — Identify the state of each species:

Reaction: $\mathrm{Fe_2O_3(s) + 3CO(g) \rightleftharpoons 2Fe(l) + 3CO_2(g)}$

• $\mathrm{Fe_2O_3}$: solid → not in $K_c$ expression
• CO: gas → in $K_c$ expression
• $\mathrm{CO_2}$: gas → in $K_c$ expression
• Fe: liquid → not in $K_c$ expression

$K_c = \frac{[\mathrm{CO_2}]^3}{[\mathrm{CO}]^3}$

Step 2 — Evaluate each option:

• (1) Add $\mathrm{CO_2}$: Increases product concentration → shifts backward (disturbs equilibrium)
• (2) Remove $\mathrm{CO_2}$: Decreases product → shifts forward (disturbs equilibrium)
• (3) Add $\mathrm{Fe_2O_3}$: Pure solid — no effect on equilibrium ✓
• (4) Remove CO: Decreases reactant → shifts backward (disturbs equilibrium)

Answer: Option (3) — Addition of $\mathrm{Fe_2O_3}$