Solutions

Step 1: Understanding azeotropes.
An azeotropic mixture is a mixture that boils at a constant temperature and composition, meaning it cannot be separated by simple distillation. For HCl and , the azeotropic mixture contains 36% HCl by mass. Step 2: Analysis of options.
(A) 48% HCl: This is not the azeotropic composition for HCl and water.
(B) 36% HCl: Correct — The azeotropic mixture of HCl and water contains 36% HCl.
(C) 22% HCl: This is not the azeotropic composition for HCl and water.
(D) 20% HCl: This is not the azeotropic composition for HCl and water.
Step 3: Conclusion.
The correct answer is (B) because the azeotropic mixture of HCl and contains 36% HCl.

Step 1: Understanding positive deviation from Raoult's law.
A positive deviation from Raoult's law occurs when the intermolecular forces between the components of the solution are weaker than the forces between the molecules of the pure substances. This causes the vapor pressure of the solution to be higher than expected. This is typically seen when the components have significantly different molecular sizes or non-ideal interactions. Step 2: Analysis of options.
(A) and : This is a non-polar combination and should follow Raoult's law more closely without significant deviation.
(B) and : This combination of two non-polar substances exhibits a positive deviation due to weaker intermolecular forces.
(C) and : This combination shows a negative deviation because hydrogen bonding occurs between the alcohol and chloroform molecules.
(D) and : This combination does not show significant deviation from Raoult's law.
Step 3: Conclusion.
The correct answer is (B) because the combination of and shows a positive deviation due to weaker intermolecular interactions.

Step 1: Temperature dependence idea.
Quantities based on volume change with temperature (thermal expansion/contraction), whereas quantities based on mass do not.
Step 2: Analyze options.
Molarity (mol L ), Normality (eq L ), and Formality (mol formula units L ) all use \emph{volume} of solution temperature dependent.
Molality (mol kg solvent) uses \emph{mass} of solvent independent of temperature.
Step 3: Conclusion.
Hence the temperature-independent concentration unit is Molality (D).

Step 1: Understand Raoult’s Law.
Raoult’s Law states that the partial vapor pressure of each volatile component in a solution is directly proportional to its mole fraction in the solution. The law is given by the equation: Where: - is the partial vapor pressure of component A in the solution. - is the mole fraction of component A in the solution. - is the vapor pressure of pure component A. Raoult’s law is valid for ideal solutions, where intermolecular forces between the solute and solvent are similar to those in the pure components.
Step 2: Ideal Solutions.
An ideal solution follows Raoult’s law exactly. The intermolecular forces between the solute and solvent are similar to the forces between the solute molecules and solvent molecules. As a result, the vapor pressure of the solution is a linear function of the mole fraction of each component. Examples: Benzene and Toluene.
Step 3: Non-ideal Solutions.
Non-ideal solutions deviate from Raoult’s law. These deviations occur because the intermolecular forces between the solute and solvent molecules are different from the forces in the pure components. In non-ideal solutions, the vapor pressure is either higher or lower than predicted by Raoult’s law. - Positive deviation: Occurs when the intermolecular forces between solute and solvent are weaker than those between the solute-solute and solvent-solvent molecules. - Negative deviation: Occurs when the intermolecular forces between solute and solvent are stronger than those between solute-solute and solvent-solvent molecules. Examples: Acetone and chloroform exhibit negative deviation, and alcohol and ether show positive deviation.
Final Answer: Raoult's law describes the vapor pressure of an ideal solution. Ideal solutions obey Raoult’s law strictly, while non-ideal solutions deviate from it due to differences in intermolecular forces.
Final Answer:

Step 1: Define Elevation of Boiling Point.
The elevation of boiling point refers to the increase in the boiling point of a solvent when a non-volatile solute is dissolved in it. This phenomenon occurs due to the reduction in the vapor pressure of the solvent, which requires a higher temperature to reach the boiling point.
Step 2: Explanation.
When a non-volatile solute is added to a solvent, it lowers the vapor pressure of the solvent because the solute particles occupy space on the surface of the liquid, thereby reducing the number of solvent molecules escaping into the vapor phase. As a result, the solvent must be heated to a higher temperature to achieve the necessary vapor pressure for boiling. The relationship between the elevation in boiling point ( ) and the amount of solute is given by the equation: Where: - is the elevation in boiling point. - is the ebullioscopic constant (a property of the solvent). - is the molality of the solute.
Final Answer: The elevation of boiling point is the increase in the boiling point of a solvent when a non-volatile solute is added, caused by the lowering of vapor pressure.
Final Answer:

Step 1: Understand colligative properties.
Colligative properties are properties that depend on the number of solute particles in a solution, not the identity of the solute particles. The common colligative properties include the depression of freezing point, elevation of boiling point, osmotic pressure, and vapour pressure lowering.
Step 2: Analyze each option.
- Vapour pressure is not a colligative property, as it depends on the nature of the solvent and solute. It is affected by the volatility of the solvent and solute, not just the number of particles. - The other properties listed (depression of freezing point, osmotic pressure, and elevation of boiling point) are all colligative properties.
Step 3: Apply to the options.
Since vapour pressure is not a colligative property, the correct answer is (A).
Final Answer:

Step 1: Understand osmotic pressure.
Osmotic pressure is the pressure exerted by a solution to prevent the flow of solvent into it through a semipermeable membrane. It depends on the concentration of solute particles in the solution.
Step 2: Analyze the compounds.
- Urea, glucose, and sucrose are non-electrolytes. They do not dissociate into ions and therefore contribute only one particle each in the solution. - Common salt (NaCl) dissociates into two ions (Na and Cl ), so it contributes two particles per formula unit, which leads to a higher osmotic pressure than the non-electrolytes.
Step 3: Apply to the options.
Since common salt dissociates into two ions, it will show abnormal osmotic pressure compared to the other non-electrolytes.
Final Answer:

Step 1: Understand Raoult's law.
Raoult's law states that the partial vapor pressure of each volatile component in a solution is directly proportional to its mole fraction in the solution. Ideal solutions obey Raoult's law perfectly, meaning they show no deviation from it.
Step 2: Understand deviations from Raoult's law.
- Non-ideal solutions show either positive or negative deviations from Raoult's law. These deviations occur when the interactions between molecules in the solution differ from those between the pure components. - Ideal solutions obey Raoult's law exactly, showing no deviation. - True solutions and colloidal solutions are not classified based on their adherence to Raoult's law.
Step 3: Apply to the options.
Non-ideal solutions are the ones that show deviations from Raoult's law, making option (C) the correct answer.
Final Answer:

Step 1: Understand specific conductance.
Specific conductance (also called conductivity) is a property of a material that describes its ability to conduct electric current. It is the inverse of resistivity and is expressed in ohm cm .
Step 2: Apply to the options.
- The unit of specific conductance is the inverse of resistance per unit length, which is ohm cm , corresponding to option (C).
Final Answer:

Step 1: Understand the concept of boiling point elevation.
Boiling point elevation occurs when a solute is added to a solvent, resulting in an increase in the boiling point. The extent of boiling point elevation depends on the number of particles in solution, which is determined by the van't Hoff factor (i).
Step 2: Analyze the van't Hoff factor.
- Glucose and sucrose are non-electrolytes, meaning they do not dissociate into ions in solution. Their van't Hoff factor (i) is 1. - NaCl dissociates into 2 ions (Na and Cl ), so its van't Hoff factor (i) is 2. - CaCl dissociates into 3 ions (Ca and 2 Cl ), so its van't Hoff factor (i) is 3.
Step 3: Apply to the options.
The higher the van't Hoff factor, the higher the number of particles in solution, leading to a greater boiling point elevation. Therefore, the solution with the highest boiling point will be the one with CaCl , which has the highest van't Hoff factor.
Final Answer: