Equilibrium constant calculation

Steps:

• K_c = [SO₃]² / ([SO₂]² [O₂]) = 280 dm³ mol⁻¹
• Substitute [SO₂] = 0.200 mol dm⁻³ and [O₂] = 0.100 mol dm⁻³: 280 = [SO₃]² / (0.200² × 0.100)
• Compute 0.200² × 0.100 = 0.0400 × 0.100 = 0.00400
• [SO₃]² = 280 × 0.00400 = 1.12; [SO₃] = √1.12 ≈ 1.06 mol dm⁻³ (rounds to 1.05)

Why A is correct:

• Matches the value solved from the K_c expression for the reaction stoichiometry.

Why the others are wrong:

• B: Results from using linear [SO₃] instead of squared in the numerator.
• C: Arises from inverting the K_c expression or miscalculating the denominator.
• D: Comes from doubling the calculated [SO₃]² before taking the square root.

Final answer: A