Equilibrium constant calculation Steps:

• K = [CH3COOH][CH3CH2OH] / [CH3COOCH2CH3] = 0.27 (water omitted as constant).
• Substitute equilibrium values: [CH3COOH] = [CH3CH2OH] = 0.42 mol dm^{-3}.
• [CH3COOCH2CH3] = (0.42 × 0.42) / 0.27.
• 0.42² = 0.1764; 0.1764 / 0.27 = 0.65 mol dm^{-3}. Why B is correct:
• 0.65 mol dm^{-3} satisfies K = (0.42)² / 0.65 ≈ 0.27 from the expression. Why the others are wrong:
• A: Gives K ≈ 0.80, too high.
• C: Gives K ≈ 0.22, too low.
• D: Gives K ≈ 0.11, too low.

Final answer: B