Consider the following four 0.1 M aqueous solutions: (A) Urea (B) NaCl (C) BaCl ₂ (D) K ₃[ Fe ( CN )₆] Which of the following represents the correct increasing order of their boiling points? (Assume complete dissociation for electrolytes)

Step-by-step solution

Elevation in boiling point is a colligative property given by T_b = i K_b m . For dilute aqueous solutions, molality is approximately equal to molarity ( m M ). Since the concentration is identical (0.1 M) for all four solutions, the elevation in boiling point is directly proportional to the van 't Hoff factor ( i ). Determining the van 't Hoff factor for each solute: (A) Urea: Non-electrolyte, so i = 1 (B) NaCl : Dissociates into Na ^+ and Cl ^- , so i = 2 (C) BaCl ₂ : Dissociates into Ba ²⁺ and 2 Cl ^- , so i = 3