Q.1: Which of the following is a colligative property? (a) Boiling point (b) Osmotic pressure (c) Viscosity (d) Surface tension
Answer: (b) Osmotic pressure Explanation: Colligative properties depend on the number of solute particles in a solution, not on the nature of the solute. Osmotic pressure is one such property.
Q.2: The molality of a solution containing 18g of glucose (C₆H₁₂O₆) in 500g of water is: (a) 0.1 m (b) 0.2 m (c) 0.5 m (d) 1.0 m
Answer: (b) 0.2 m Explanation: Molality (m) = moles of solute / mass of solvent (kg). Moles of glucose = 18/180 = 0.1 moles. Molality = 0.1 moles / 0.5 kg = 0.2 m.
Q.3: Raoult’s Law is applicable to: (a) Non-ideal solutions (b) Dilute solutions (c) Ideal solutions (d) Concentrated solutions
Answer: (c) Ideal solutions Explanation: Raoult’s Law states that the partial vapor pressure of each volatile component in an ideal solution is directly proportional to its mole fraction.
Q.4: Which of the following statements is true for an ideal solution? (a) ΔHmix = 0 (b) ΔVmix ≠ 0 (c) ΔHmix ≠ 0 (d) ΔVmix ≠ 0
Answer: (a) ΔH_mix = 0 Explanation: For an ideal solution, the enthalpy change of mixing (ΔH_mix) is zero because the intermolecular forces between the molecules of the solute and solvent are similar to those in the pure components.
Q.5: The boiling point of a solution increases if: (a) Solute is non-volatile (b) Solute is volatile (c) Pressure is decreased (d) None of the above
Answer: (a) Solute is non-volatile Explanation: Boiling point elevation occurs when a non-volatile solute is added to a solvent, increasing the boiling point of the solution compared to the pure solvent.
Q.6: Which of the following expresses Henry’s Law? (a) P = k_H * x (b) P = k_H / x (c) P = x / k_H (d) P = k_H + x
Answer: (a) P = k_H * x Explanation: Henry’s Law states that the partial pressure of a gas in a liquid is directly proportional to the mole fraction of the gas in the liquid, where k_H is Henry’s constant.
Q.7: The term used to describe the lowering of vapor pressure in a solution is: (a) Relative lowering of vapor pressure (b) Absolute lowering of vapor pressure (c) Osmotic pressure (d) Elevation of boiling point
Answer: (a) Relative lowering of vapor pressure Explanation: Relative lowering of vapor pressure is the ratio of the lowering of vapor pressure to the vapor pressure of the pure solvent, which is a colligative property.
Q.8: Which among the following is a suitable example of a colloidal solution? (a) Salt in water (b) Sugar in water (c) Milk (d) Benzene in water
Answer: (c) Milk Explanation: Milk is an example of a colloidal solution where fat globules are dispersed in water.
Q.9: When a non-volatile solute is added to a solvent, the vapor pressure of the solvent: (a) Increases (b) Decreases (c) Remains the same (d) None of the above
Answer: (b) Decreases Explanation: The addition of a non-volatile solute decreases the vapor pressure of the solvent because the solute particles occupy space at the surface, reducing the number of solvent molecules that can escape into the vapor phase.
Q.10: The process of separation of solute particles from a solvent using a semi-permeable membrane is known as: (a) Diffusion (b) Osmosis (c) Dialysis (d) Filtration
Answer: (b) Osmosis Explanation: Osmosis is the process in which solvent molecules move through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
Q.11: Which of the following can show positive deviation from Raoult’s law? (a) Ethanol and water (b) Acetone and chloroform (c) Benzene and toluene (d) n-Hexane and n-Heptane
Answer: (a) Ethanol and water Explanation: Positive deviation from Raoult’s law occurs when the intermolecular forces between the solute and solvent are weaker than those between the molecules of the pure components, as seen in the ethanol-water mixture.
Q.12: The freezing point of a solution is: (a) Higher than the freezing point of the pure solvent (b) Lower than the freezing point of the pure solvent (c) Equal to the freezing point of the pure solvent (d) None of the above
Answer: (b) Lower than the freezing point of the pure solvent Explanation: Freezing point depression occurs when a solute is added to a solvent, causing the freezing point of the solution to be lower than that of the pure solvent.
Q.13: Which factor does not affect the solubility of a solid in a liquid? (a) Temperature (b) Pressure (c) Nature of the solute and solvent (d) Concentration
Answer: (d) Concentration Explanation: The solubility of a solid in a liquid is influenced by temperature, pressure (in the case of gases), and the nature of the solute and solvent, but not by the concentration of the solution.
Q.14: A solution has a concentration of 1 ppm. This means: (a) 1 g of solute in 1 L of solution (b) 1 mg of solute in 1 L of solution (c) 1 g of solute in 1 kg of solution (d) 1 mg of solute in 1 kg of solution
Answer: (b) 1 mg of solute in 1 L of solution Explanation: 1 ppm (part per million) corresponds to 1 milligram of solute in 1 liter of solution.
Q.15: Which of the following is not a method to express the concentration of a solution? (a) Molality (b) Molarity (c) Normality (d) Fluidity
Answer: (d) Fluidity Explanation: Molality, molarity, and normality are all methods to express the concentration of a solution, whereas fluidity is a measure of a liquid’s flow characteristics.
Q.16: The process by which molecules of a solvent pass through a semi-permeable membrane from a dilute solution to a concentrated solution is called: (a) Diffusion (b) Osmosis (c) Dialysis (d) Filtration
Answer: (b) Osmosis Explanation: Osmosis is the process where solvent molecules move from a region of lower solute concentration to a region of higher solute concentration through a semi-permeable membrane.
Q.17: The addition of which of the following will not change the boiling point of water? (a) NaCl (b) C₂H₅OH (c) CH₃OH (d) H₂
Answer: (d) H₂ Explanation: H₂ (hydrogen gas) does not dissolve significantly in water and hence will not affect its boiling point, unlike NaCl, C₂H₅OH, and CH₃OH which do.
Q.18: The van’t Hoff factor (i) for a dilute solution of K₄[Fe(CN)₆] is: (a) 1 (b) 2 (c) 4 (d) 5
Answer: (d) 5 Explanation: K₄[Fe(CN)₆] dissociates into 4 K⁺ ions and 1 [Fe(CN)₆]⁴⁻ ion, giving a total of 5 particles in solution. Therefore, the van’t Hoff factor (i) is 5.
Q.19: Which of the following solutions will have the highest boiling point? (a) 1 M NaCl (b) 1 M glucose (c) 1 M sucrose (d) 1 M urea
Answer: (a) 1 M NaCl Explanation: NaCl dissociates into two ions (Na⁺ and Cl⁻) in solution, increasing the number of particles and hence the boiling point more than the non-electrolytes (glucose, sucrose, urea) which do not dissociate.
Q.20: The colligative property used to determine the molar mass of a solute is: (a) Viscosity (b) Surface tension (c) Depression in freezing point (d) Refractive index
Answer: (c) Depression in freezing point Explanation: Depression in freezing point, a colligative property, is used to determine the molar mass of a solute by measuring the extent to which the freezing point of the solvent is lowered.
Q.21: The process of separating colloidal particles from impurities by means of diffusion through a semi-permeable membrane is called: (a) Dialysis (b) Osmosis (c) Diffusion (d) Filtration
Answer: (a) Dialysis Explanation: Dialysis is used to separate colloidal particles from smaller impurities by allowing only the smaller particles to pass through a semi-permeable membrane.
Q.22: Which of the following substances will show minimum elevation in boiling point when dissolved in 1 kg of water? (a) NaCl (b) Urea (c) K₂SO₄ (d) Glucose
Answer: (b) Urea Explanation: Urea does not ionize and provides only one particle per molecule, resulting in a smaller elevation in boiling point compared to NaCl and K₂SO₄ which ionize to produce more particles.
Q.23: For a given solvent, the boiling point of a solution is always: (a) Higher than that of the pure solvent (b) Lower than that of the pure solvent (c) Same as that of the pure solvent (d) None of the above
Answer: (a) Higher than that of the pure solvent Explanation: The presence of a solute in a solvent elevates the boiling point of the solution compared to the pure solvent.
Q.24: Which of the following statements is correct regarding a 0.1 M NaCl solution and a 0.1 M glucose solution?
(a) Both will have the same osmotic pressure
(b) NaCl solution will have higher osmotic pressure
(c) Glucose solution will have higher osmotic pressure
(d) Both will have the same boiling point
Answer: (b) NaCl solution will have higher osmotic pressure Explanation: NaCl dissociates into two ions, increasing the number of solute particles and thereby the osmotic pressure compared to glucose which does not dissociate.
Q.25: The molality of a solution in which 0.5 mole of solute is dissolved in 250g of solvent is: (a) 1 m (b) 2 m (c) 0.5 m (d) 4 m
Answer: (b) 2 m Explanation: Molality (m) = moles of solute / mass of solvent (kg). Molality = 0.5 moles / 0.25 kg = 2 m.
Q.26: The freezing point of a solution is affected by: (a) The nature of the solute (b) The amount of solute (c) The nature of the solvent (d) All of the above
Answer: (d) All of the above Explanation: The freezing point of a solution depends on the nature of the solute, the amount of solute, and the nature of the solvent.
Q.27: Which of the following has the highest van’t Hoff factor (i)? (a) KCl (b) Na₂SO₄ (c) BaCl₂ (d) Glucose
Answer: (b) Na₂SO₄ Explanation: Na₂SO₄ dissociates into three ions (2 Na⁺ and 1 SO₄²⁻), giving a van’t Hoff factor of 3, which is higher than that of KCl (2), BaCl₂ (3), and glucose (1, as it does not dissociate).
Q.28: Which of the following statements is not true for ideal solutions? (a) They follow Raoult’s law over the entire range of concentration (b) ΔH_mix = 0 (c) ΔV_mix = 0 (d) They are formed only by non-polar solvents
Answer: (d) They are formed only by non-polar solvents Explanation: Ideal solutions can be formed by both polar and non-polar solvents as long as the intermolecular forces between the solute and solvent molecules are similar to those in the pure components.
Q.29: The solubility of gases in liquids decreases with: (a) Increase in pressure (b) Increase in temperature (c) Increase in concentration (d) Decrease in temperature
Answer: (b) Increase in temperature Explanation: The solubility of gases in liquids generally decreases with an increase in temperature because gas molecules gain kinetic energy and escape from the solvent.
Q.30: Which of the following solutions shows a negative deviation from Raoult’s law? (a) Ethanol and acetone (b) Benzene and toluene (c) Chloroform and acetone (d) Hexane and heptane
Answer: (c) Chloroform and acetone Explanation: Negative deviation from Raoult’s law occurs when the intermolecular forces between solute and solvent molecules are stronger than those in the pure components, as seen in chloroform and acetone.
Q.31: The osmotic pressure of a solution increases with: (a) Decrease in temperature (b) Increase in temperature (c) Increase in the number of solute particles (d) Both (b) and (c)
Answer: (d) Both (b) and (c) Explanation: Osmotic pressure is directly proportional to the number of solute particles and the temperature of the solution.
Q.32: The ebullioscopic constant (Kb) depends on: (a) Nature of the solute (b) Nature of the solvent (c) Temperature (d) Both (a) and (b)
Answer: (b) Nature of the solvent Explanation: The ebullioscopic constant (K_b) is a property of the solvent and does not depend on the solute.
Q.33: The depression in freezing point is directly proportional to: (a) The molarity of the solution (b) The molality of the solution (c) The normality of the solution (d) The volume of the solution
Answer: (b) The molality of the solution Explanation: Depression in freezing point is a colligative property that is directly proportional to the molality of the solution.
Q.34: The boiling point of a liquid is the temperature at which its vapor pressure is equal to: (a) 1 atm (b) 1 torr (c) The external pressure (d) The atmospheric pressure
Answer: (c) The external pressure Explanation: The boiling point of a liquid is defined as the temperature at which its vapor pressure equals the external pressure applied to it.
Q.35: The phenomenon of osmosis is due to: (a) Diffusion of solute particles (b) Diffusion of solvent particles (c) Movement of solute particles against a concentration gradient (d) None of the above
Answer: (b) Diffusion of solvent particles Explanation: Osmosis is the movement of solvent particles through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
Q.36: An azeotropic mixture of two liquids has a boiling point: (a) Higher than either of the pure components (b) Lower than either of the pure components (c) Same as the boiling point of the pure component with the lower boiling point (d) Same as the boiling point of the pure component with the higher boiling point
Answer: (a) Higher than either of the pure components Explanation: An azeotropic mixture has a constant boiling point that can be higher or lower than the boiling points of the individual components, but when it shows a positive deviation, it is higher than the boiling point of either pure component.
Q.37: The term ‘isotonic solutions’ refers to: (a) Solutions with the same concentration of solute (b) Solutions with the same osmotic pressure (c) Solutions with the same boiling point (d) Solutions with the same freezing point
Answer: (b) Solutions with the same osmotic pressure Explanation: Isotonic solutions have the same osmotic pressure, meaning they have equal concentrations of solute particles.
Q.38: Which of the following has the highest value of i (van’t Hoff factor)? (a) NaCl (b) K₂SO₄ (c) Al₂(SO₄)₃ (d) C₆H₁₂O₆
Answer: (c) Al₂(SO₄)₃ Explanation: Al₂(SO₄)₃ dissociates into 5 ions (2 Al³⁺ and 3 SO₄²⁻), resulting in the highest van’t Hoff factor (i = 5) compared to NaCl (2), K₂SO₄ (3), and C₆H₁₂O₆ (1).
Q.39: Which of the following is a non-volatile solute? (a) NaCl (b) C₂H₅OH (c) CH₃COOH (d) CO₂
Answer: (a) NaCl Explanation: NaCl is a non-volatile solute, meaning it does not evaporate easily and thus increases the boiling point of the solvent.
Q.40: Which of the following statements is incorrect? (a) The boiling point of a solution is always higher than that of the pure solvent (b) The freezing point of a solution is always lower than that of the pure solvent (c) The vapor pressure of a solution is higher than that of the pure solvent (d) The osmotic pressure of a solution is higher than that of the pure solvent
Answer: (c) The vapor pressure of a solution is higher than that of the pure solvent Explanation: The vapor pressure of a solution is lower than that of the pure solvent due to the presence of non-volatile solute particles which lower the escaping tendency of solvent molecules.
Q.41: Henry’s law constant (kH) is dependent on: (a) Temperature (b) Pressure (c) Nature of the gas (d) Both (a) and (c)
Answer: (d) Both (a) and (c) Explanation: Henry’s law constant (k_H) is dependent on the temperature and the nature of the gas.
Q.42: A solution containing 10g of solute in 100g of solvent is referred to as: (a) 10% (w/w) solution (b) 10% (v/v) solution (c) 10 ppm solution (d) 10 molal solution
Answer: (a) 10% (w/w) solution Explanation: A 10% (w/w) solution means 10g of solute is dissolved in 100g of solvent.
Q.43: The addition of a non-volatile solute to a solvent results in: (a) Increase in vapor pressure (b) Decrease in boiling point (c) Decrease in freezing point (d) Decrease in osmotic pressure
Answer: (c) Decrease in freezing point Explanation: The addition of a non-volatile solute lowers the freezing point of the solvent, a phenomenon known as freezing point depression.
Q.44: The unit of molality is: (a) mol/L (b) mol/kg (c) mol/g (d) mol/m³
Answer: (b) mol/kg Explanation: Molality is expressed in moles of solute per kilogram of solvent (mol/kg).
Q.45: The van’t Hoff factor (i) for a dilute solution of AlCl₃ is: (a) 1 (b) 2 (c) 3 (d) 4
Answer: (d) 4 Explanation: AlCl₃ dissociates into 4 ions (1 Al³⁺ and 3 Cl⁻), giving a van’t Hoff factor (i) of 4.
Q.46: Colligative properties depend on: (a) The nature of solute particles (b) The number of solute particles (c) The chemical identity of the solute (d) The physical state of the solute
Answer: (b) The number of solute particles Explanation: Colligative properties are dependent on the number of solute particles present in a solution, not their nature.
Q.47: Which of the following solutions is not an example of a colloid? (a) Milk (b) Butter (c) Salt in water (d) Smoke
Answer: (c) Salt in water Explanation: Salt in water is a true solution, not a colloid. Colloids have larger dispersed particles, such as those in milk, butter, and smoke.
Q.48: The concentration term that is temperature-independent is: (a) Molarity (b) Molality (c) Normality (d) Volume percentage
Answer: (b) Molality Explanation: Molality is temperature-independent as it is based on the mass of the solvent, which does not change with temperature.
Q.49: Which of the following will not change the vapor pressure of a solution? (a) Changing the amount of solute (b) Changing the nature of the solute (c) Changing the temperature (d) Changing the solvent
Answer: (b) Changing the nature of the solute Explanation: Vapor pressure depends on the number of solute particles and temperature, not the chemical nature of the solute.
Q.50: The freezing point of 1 molal solution of a non-electrolyte in water is: (a) 0°C (b) -1.86°C (c) -3.72°C (d) 100°C
Answer: (b) -1.86°C Explanation: The freezing point depression constant (K_f) for water is 1.86°C kg/mol. Thus, a 1 molal solution of a non-electrolyte will lower the freezing point by 1.86°C.
Q.51: The term ‘colligative properties’ refers to properties that: (a) Depend on the chemical nature of the solute (b) Depend on the number of solute particles (c) Depend on the physical state of the solute (d) Depend on the volume of the solvent
Answer: (b) Depend on the number of solute particles Explanation: Colligative properties depend on the number of solute particles in a solution, regardless of their chemical nature.
Q.52: The ratio of the number of moles of solute to the mass of solvent in kg is called: (a) Molarity (b) Molality (c) Normality (d) Volume percentage
Answer: (b) Molality Explanation: Molality is defined as the number of moles of solute per kilogram of solvent.
Q.53: The vapor pressure of a solution is lower than that of the pure solvent because: (a) Solute particles attract solvent particles (b) Solute particles repel solvent particles (c) Solute particles occupy space (d) None of the above
Answer: (a) Solute particles attract solvent particles Explanation: Solute particles attract solvent particles, reducing their ability to escape into the vapor phase, thereby lowering the vapor pressure.
Q.54: The solubility of a gas in a liquid at constant temperature is directly proportional to: (a) The volume of the gas (b) The pressure of the gas (c) The temperature of the gas (d) The nature of the gas
Answer: (b) The pressure of the gas Explanation: According to Henry’s law, the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid.
Q.55: Which one of the following statements about Raoult’s law is not correct? (a) It is applicable to ideal solutions (b) It relates vapor pressure of a solution to the mole fraction of the solvent (c) It is valid over a wide range of concentrations (d) It is not applicable to non-ideal solutions
Answer: (c) It is valid over a wide range of concentrations Explanation: Raoult’s law is only strictly applicable to ideal solutions and is most accurate at low concentrations of solute.
Q.56: In a solution of two liquids, A and B, if the partial vapor pressure of A is higher than expected from Raoult’s law, the solution exhibits: (a) Positive deviation (b) Negative deviation (c) No deviation (d) Ideal behavior
Answer: (a) Positive deviation Explanation: Positive deviation occurs when the intermolecular forces between unlike molecules are weaker than those between like molecules, resulting in higher vapor pressures.
Q.57: When the freezing point of a solvent is lowered upon the addition of a non-volatile solute, it is called: (a) Boiling point elevation (b) Freezing point depression (c) Vapor pressure lowering (d) Osmotic pressure
Answer: (b) Freezing point depression Explanation: Freezing point depression refers to the decrease in the freezing point of a solvent due to the addition of a non-volatile solute.
Q.58: Which one of the following does not affect the colligative properties of a solution? (a) Nature of the solute (b) Number of solute particles (c) Concentration of solute particles (d) Temperature
Answer: (a) Nature of the solute Explanation: Colligative properties depend on the number and concentration of solute particles, not their chemical nature.
Q.59: A 0.1 M solution of which of the following substances will have the highest boiling point? (a) NaCl (b) KNO₃ (c) MgCl₂ (d) C₆H₁₂O₆
Answer: (c) MgCl₂ Explanation: MgCl₂ dissociates into three ions (1 Mg²⁺ and 2 Cl⁻), giving a higher elevation in boiling point compared to NaCl (2 ions), KNO₃ (2 ions), and C₆H₁₂O₆ (non-electrolyte).
Q.60: The presence of which of the following will not affect the freezing point of water? (a) NaCl (b) Urea (c) Ethanol (d) Water
Answer: (d) Water Explanation: Adding more water to water does not affect its freezing point, whereas solutes like NaCl, urea, and ethanol will lower the freezing point.
