Solutions

Step 1: Understanding the Concept:
Accuracy in concentration terms depends on their dependence on temperature. Molarity, normality, and formality are volume-dependent, and volume changes with temperature.

Step 2: Detailed Explanation:
• Molarity (M): Moles of solute per liter of solution. Volume of solution is temperature-dependent. • Normality (N): Gram equivalents of solute per liter of solution. Also volume-dependent. • Formality (F): Formula weight of solute per liter of solution. Volume-dependent. • Molality (m): Moles of solute per kilogram of solvent. Mass is independent of temperature, making molality the most accurate concentration term under varying temperature conditions.

Step 3: Final Answer:
Molality is the most accurate expression as it is independent of temperature, which corresponds to option (D).

Step 1: Understanding the Concept:
Osmotic pressure ( ) for a solution is given by , where i is van't Hoff factor. For urea (non-electrolyte), i = 1.
Step 2: Detailed Explanation:
Given: C = 0.2 M, T = 300 K, R = 0.082 L atm mol K . atm.
Step 3: Final Answer:
The osmotic pressure is 4.92 atm, option (A).

Step 1: Understanding the Concept:
Elevation in boiling point .
Step 2: Detailed Explanation:
dissociates into 4 ions ( ), so is maximum. Hence, shows maximum elevation.
Step 3: Final Answer:
exhibits maximum elevation.

Step 1: Understanding the Concept:
Deviation from Raoult's law depends on intermolecular interactions.
Step 2: Detailed Explanation:
Stronger A-B attraction means less escaping tendency, so vapour pressure is lower, showing negative deviation.
Step 3: Final Answer:
The solution shows negative deviation.

Step 1: Understanding the Concept:
.
Step 2: Detailed Explanation:
Total moles = mol. Total volume = L. Molarity = M.
Step 3: Final Answer:
The molarity is 0.3 M.