Free NEET Chemistry multiple-choice questions on Colligative Properties. Attempt each question and reveal the answer with a full explanation.
Which statement about the ebullioscopic constant is correct? It is a property of the solvent only It depends on the nature of the solute It is independent of the molality of the solution It decreases with an increase in the molecular weight of the solute Which property is used to calculate the molar mass of polymers? Osmotic Pressure Relative lowering of vapour pressure Elevation in boiling point Depression in freezing point If molality of the dilute solution is doubled, the value of molal depression constant ( K f ) will be: Unchanged Doubled Halved Tripled People taking a lot of salt in their diet experience swelling of tissue cells and intercellular spaces. This phenomenon is called: Edema Anoxia Plasmolysis Hemolysis In the desalination of seawater by reverse osmosis, the pressure applied to the seawater side must be: Greater than the osmotic pressure Less than the osmotic pressure Equal to the atmospheric pressure Equal to the osmotic pressure Two solutions A and B are separated by a semi-permeable membrane. If liquid flows from A to B , then . Solution A is less concentrated than solution B Solution B is less concentrated than solution A Both solutions have the same concentration Solution A has a higher osmotic pressure than B When a non-volatile solute is dissolved in a solvent, the entropy of the liquid phase: Increases Decreases Remains the same Becomes zero The molal elevation constant K b for water is 0.512 ,K kg mol -1 . This value means that 1 mole of a non-volatile non-electrolyte dissolved in 1000 ,g of water will raise the boiling point by: 0.512 ,K 1.024 ,K 100.512 ,K 273.512 ,K Which property of a solution is used to define the concept of 'reverse osmosis'? Osmotic pressure Vapour pressure Relative lowering of vapour pressure Freezing point depression The elevation in boiling point for 1 ,molal solution of glucose is 0.5 ,K . The depression in freezing point for 2 ,molal solution of glucose in the same solvent is ( K b = 0.5, K f = 1.86 ): 3.72 ,K 1.86 ,K 0.5 ,K 1.0 ,K Sea water is desalinated by: Reverse osmosis Osmosis Filtration Electrolysis In the process of osmosis, the osmotic pressure is: The excess pressure that must be applied to the solution side to prevent osmosis The pressure developed by the solvent molecules hitting the membrane The pressure applied to the pure solvent to force it into the solution Atmospheric pressure minus the vapor pressure of the solution Which of the following aqueous solutions will have the highest osmotic pressure? 0.1 ,M ,Na 3PO 4 0.1 ,M ,BaCl 2 0.1 ,M ,NaCl 0.1 ,M ,Glucose The unit of ebullioscopic constant K b is . K kg mol -1 mol kg K -1 kg mol -1 K -1 K mol kg -1 Colligative properties of a solution depend only on: The number of solute particles The chemical nature of the solute The chemical nature of the solvent The size of the solute particles In osmosis, the movement of solvent molecules across a semi-permeable membrane occurs from: Low solute concentration to high solute concentration High solute concentration to low solute concentration High osmotic pressure to low osmotic pressure Solution to pure solvent The unit of osmotic pressure is the same as that of: Pressure Energy Force Temperature The cryoscopic constant of water is 1.86 K kg mol -1 . If an aqueous solution of a non-electrolyte freezes at -0.186 C , its molality is: 0.1 m 0.01 m 1.0 m 0.2 m Blood cells retain their normal shape in solution which are to blood. Isotonic Hypotonic Hypertonic Equinormal The cryoscopic constant ( K f ) of a solvent is 4.0 K kg mol -1 . A 0.05 m solution of a non-electrolyte in this solvent will show a freezing point depression of: 0.2 K 0.05 K 4.0 K 0.8 K Identify the incorrect statement regarding the ebullioscopic constant ( K b ): It depends on the nature of the solute It is also called the molal elevation constant Its units are K kg mol -1 It is a characteristic property of the solvent Which of the following properties is NOT used to determine the molar mass of a non-volatile solute? Density of the solution Osmotic pressure Elevation of boiling point Relative lowering of vapor pressure The osmotic pressure of a solution increases when: Temperature is increased Volume is increased Solute is removed Atmospheric pressure is decreased The freezing point of a 0.05 ,m solution of a non-electrolyte in water is (given K f = 1.86 ,K ,kg ,mol -1 ): -0.093 C 0.093 C -0.186 C -0.046 C The unit of the cryoscopic constant is: K ,kg ,mol -1 K ,mol ,kg -1 K -1 ,kg ,mol -1 kg ,mol ,K -1 1.00 g of a non-electrolyte solute (molar mass 250g mol -1 ) was dissolved in 51.2 g of benzene. If the freezing point depression constant K f of benzene is 5.12 K kg mol -1 , the freezing point of benzene will be lowered by:- 0.4 K 0.3 K 0.5 K 0.2 K During osmosis, flow of water through a semipermeable membrane is:- From solution having higher concentration only Form both sides of semipermeable membrane with equal flow rates From both sides of semipermeable membrane with unequal flow rates From solution having lower concentration only The freezing point depression constant ( K f ) of benzene is 5.12 K kg mol -1 . The freezing point depression for the solution of molality 0.078 m containing a non-electrolyte solute in benzene is (rounded off upto two decimal places) : 0.80 K 0.40 K 0.60 K 0.20 K The plot of osmotic pressure ( ) vs concentration ( mol L -1 ) for a solution gives a straight line with slope 25.73 L bar mol -1 . The temperature at which the osmotic pressure measurement is done is (Use R = 0.083 L bar mol -1 K -1 ) 37°C 310°C 25.73°C 12.05°C Which of the following aqueous solution will exhibit highest boiling point? 0.015M C6H12O6 0.01M Urea 0.01M KNO3 0.01M Na2SO4 What is the boiling point of a 0.1 molal aqueous solution of KCl ? (Given K b for water = 0.52 K kg mol -1 ) 373.254 K 373.150 K 373.104 K 100.104 K An aqueous solution is 1.00 molal in KI . Which change will cause the vapour pressure of the solution to increase? Addition of water Addition of NaCl Addition of more KI Lowering the temperature Calculate the mass of urea ( NH 2CONH 2 ) required in making 2.5 kg of 0.25 molal aqueous solution. 37 g 40 g 25 g 15 g The relationship between K b and K f for a given solvent can be stated as: They are independent constants for each solvent They are always equal They are related by the density of the solvent They depend on the nature of the solute Which of the following aqueous solutions has the highest boiling point? 1.0 M Na2SO4 1.0 M MgCl2 1.0 M NaCl 1.0 M Urea During osmosis, flow of water through a semi-permeable membrane is . From solution having lower concentration only From solution having higher concentration only From both sides of semi-permeable membrane with unequal rates From both sides of semi-permeable membrane with equal rates A solution is prepared by dissolving 10 ,g of a non-volatile solute in 200 ,g of water. It has a boiling point of 100.1 C . If K b for water is 0.52 ,K ,kg ,mol -1 , what is the molar mass of the solute? 260 g/mol 130 g/mol 52 g/mol 26 g/mol The cryoscopic constant depends on: Nature of the solvent Nature of the solute Concentration of the solution Enthalpy of vaporization A 5 % solution (by mass) of cane sugar (M.W. = 342) is isotonic with 0.877 % solution of substance X . The molar mass of X is: 59.9 g/mol 34.2 g/mol 180 g/mol 120 g/mol The boiling point of a 0.2 ,mol ,kg -1 solution of X in water is greater than that of a 0.2 ,mol ,kg -1 solution of Y in water. This implies that: X is undergoing dissociation or Y is undergoing association X is undergoing association Molar mass of X is greater than Y Molar mass of Y is greater than X If the density of a 2 M aqueous solution of NaCl is 1.2 g/mL , what is the molality of the solution? (Atomic masses: Na = 23, Cl = 35.5 ) 1.85 m 2.14 m 1.67 m 2.00 m Which of the following aqueous solutions has the highest boiling point? 1.0 M Na 2SO 4 1.0 M NaCl 1.0 M MgCl 2 1.0 M Urea The diagram below represents the vapour pressure vs temperature curves for a pure solvent and a solution. What does the distance AB represent? Elevation in boiling point Depression in freezing point Relative lowering of vapour pressure Osmotic pressure If 1 ,g of urea ( M.W. = 60 ) is dissolved in 100 ,g of a solvent with K b = 0.6 ,K kg mol -1 , the elevation in boiling point is: 0.1 ,K 0.01 ,K 0.6 ,K 0.06 ,K Which of the following is the best method for determining the molar mass of polymers and proteins? Osmotic pressure Elevation in boiling point Depression in freezing point Relative lowering of vapour pressure The best colligative property to determine the molar mass of polymers is osmotic pressure because: The pressure change is large enough to be measured even for very dilute solutions It is the only property applicable to non-electrolytes It does not require knowledge of the density of the solution It is independent of temperature When 25 ,g of an unknown non-volatile solute is dissolved in 100 ,g of benzene, the boiling point is raised by 0.25 C . What is the molecular weight of the solute? ( K b for benzene = 2.53 ,K ,kg ,mol -1 ) 2530 253 25.3 1265 The latent heat of fusion of ice is 333 ,J ,g -1 . The molal depression constant K f for water is: 1.86 ,K ,kg ,mol -1 0.52 ,K ,kg ,mol -1 1.12 ,K ,kg ,mol -1 3.33 ,K ,kg ,mol -1 The ebullioscopic constant for water is 0.51 ,K ,kg ,mol -1 . What is the boiling point of a solution containing 0.1 ,mol of NaCl in 1000 ,g of water? (Assume 100 % ionization) 100.102 C 100.051 C 100.204 C 101.020 C The osmotic pressure of a 0.01 ,M aqueous solution of cane sugar at 300 ,K is: ( R = 0.0821 ,L atm K -1 mol -1 ) 0.246 atm 2.46 atm 0.024 atm 24.6 atm For a given aqueous solution, the elevation in boiling point is 0.52 ,K . What will be the depression in freezing point for the same solution? ( K b = 0.52 ,K kg mol -1 , K f = 1.86 ,K kg mol -1 ) 1.86 K 0.52 K 1.00 K 3.57 K The boiling point of a solution containing 5 g of a non-volatile solute in 95 g of water is 100.26 C . The molar mass of the solute is ( K b = 0.52 K kg mol -1 ): 105.3 g/mol 210.6 g/mol 52.6 g/mol 150 g/mol When 2.0 g of a compound X is dissolved in 50 g of benzene, the freezing point is lowered by 0.40 K . If the cryoscopic constant for benzene is 5.12 K kg mol -1 , the molar mass of X is: 512 g/mol 256 g/mol 128 g/mol 1024 g/mol What is the boiling point of a solution containing 0.5 mol of a non-volatile solute in 500 g of water? ( K b for water = 0.52 K kg mol -1 ) 100.52 C 100.26 C 101.04 C 100.13 C The phenomenon of the rising of the boiling point of a solvent on the addition of a non-volatile solute is due to: Lowering of vapor pressure Increase in surface area Decrease in intermolecular forces Increase in kinetic energy Ethylene glycol is used as an antifreeze in car radiators. Which property of the solution is utilized here? Depression in freezing point Elevation in boiling point Lowering of vapour pressure Increase in osmotic pressure Calculate the elevation in boiling point for a 0.01 ,m aqueous solution of MgCl 2 (Assume 100 % dissociation, K b for water = 0.52 ,K ,kg ,mol -1 ). 0.0156 ,K 0.0052 ,K 0.0104 ,K 0.0208 ,K During reverse osmosis, the solvent moves through a semi-permeable membrane from a solution of: Higher concentration to lower concentration by applying external pressure Lower concentration to higher concentration by applying external pressure Higher concentration to lower concentration spontaneously Lower concentration to higher concentration spontaneously A solution of sucrose (molar mass = 342 ,g/mol ) is prepared by dissolving 68.4 ,g in 1000 ,g of water. The freezing point of the solution is: ( K f = 1.86 ,K ,kg ,mol -1 ) -0.372 C -0.186 C 0.372 C -0.558 C If the boiling point of an aqueous solution is 100.26 C , what is its freezing point? ( K b = 0.52, K f = 1.86 ,K ,kg ,mol -1 ) -0.93 C -1.86 C -0.52 C -0.26 C Which of the following properties of a solvent determines the magnitude of the ebullioscopic constant ( K b )? Enthalpy of vaporization and Boiling point Enthalpy of fusion and Freezing point Density and Molar mass Viscosity and Surface tension An aqueous solution of 6.00 ,g urea in 500 ,mL has an osmotic pressure 1 . Another solution of 6.00 ,g glucose in 500 ,mL has an osmotic pressure 2 . At the same temperature: 1 > 2 1 < 2 1 = 2 1 = 2 2 During the freezing of an aqueous solution of sugar, which of the following substances separates out first as a solid? Pure ice Sugar crystals A mixture of sugar and ice Liquid sugar A solution of urea (mol. mass 56 g mol -1 ) boils at 100.18 C at the atmospheric pressure. If K f and K b for water are 1.86 and 0.512K kg mol -1 respectively , the above solution will freeze at :- -6.54 C -0.654 C 6.54 C 0.654 C At 100°C the vapour pressure of a solution of 6.5g of a solute in 100 g water is 732 mm. If K b = 0.52 , the boiling point of this solution will be :- 101°C 100°C 102°C 103°C The following solutions were prepared by dissolving 10 g of glucose ( C6H12O6 ) in 250 ml of water ( P 1 ), 10 g of urea ( CH4N2O ) in 250 ml of water ( P 2 ) and 10 g of sucrose ( C12H22O11 ) in 250 ml of water ( P 3 ). The right option for the decreasing order of osmotic pressure of these solutions is : P 1 > P 2 > P 3 P 2 > P 3 > P 1 P 3 > P 1 > P 2 P 2 > P 1 > P 3 Which of the following is NOT a colligative property? Refractive index Osmotic pressure Elevation in boiling point Depression in freezing point At a particular temperature, the osmotic pressure of a solution of cane sugar is 5.07 atm and that of a solution of glucose is 2.53 atm . If 100 mL of the sugar solution is mixed with 100 mL of the glucose solution, the osmotic pressure of the resulting solution at the same temperature will be: 3.80 atm 7.60 atm 1.27 atm 5.07 atm 200 mL of an aqueous solution of a protein contains its 1.26 g . The osmotic pressure of this solution at 300 K is found to be 2.57 10 -3 bar. The molar mass of protein will be ( R = 0.083 L bar mol -1 K -1 ): 61038 g/mol 51022 g/mol 122044 g/mol 31011 g/mol When a non-volatile solute is added to a solvent, the freezing point of the solution decreases because: The vapour pressure of the solution becomes lower than that of the pure solid solvent at the freezing point The vapour pressure of the solution increases The boiling point of the solution decreases The molecules of the solute provide more surface area for freezing At 100 C , the vapour pressure of a solution of 6.5 g of a non-volatile solute in 100 g water is 732 mm Hg . If K b = 0.52 K kg mol -1 , the boiling point of this solution will be: 101.0 C 100.0 C 102.0 C 100.5 C The molal elevation constant K b of a solvent is related to its latent heat of vaporisation L v (in J g -1 ) by the expression: K b = R T b 2 1000 L v K b = 1000 R T b 2 L v K b = L v 1000 R T b 2 K b = R T b 1000 L v Calculate the molal depression constant K f for water if its latent heat of fusion is 80 ,cal/g . ( R = 2 ,cal mol -1 K -1 , Freezing point of water = 273 ,K ) 1.86 ,K kg mol -1 1.52 ,K kg mol -1 0.52 ,K kg mol -1 2.12 ,K kg mol -1 A solution containing 62 ,g ethylene glycol in 250 ,g water is cooled to -10 C . If K f for water is 1.86 ,K ,kg ,mol -1 , the amount of ice (in g) that separates out is: 64 161 93 250 The ebullioscopic constant ( K b ) of a solvent can be calculated using the formula: K b = R T b 2 M 1000 vap H K b = 1000 vap H R T b 2 M K b = R T b 2 1000 M vap H K b = R T b M 1000 vap H 2 A 1.2 % solution of an unknown non-volatile substance is isotonic with a 3 % solution of glucose (molar mass = 180 ,g/mol ). What is the molar mass of the unknown substance? 72 g/mol 120 g/mol 180 g/mol 36 g/mol A solution of urea (mol. mass 60 g/mol ) boils at 100.18 C at the atmospheric pressure. If K b and K f for water are 0.512 and 1.86 K kg mol -1 respectively, the above solution will freeze at: -0.654 °C -1.86 °C 0.654 °C 6.54 °C In reverse osmosis, the solvent flows: From concentrated solution to dilute solution through a semi-permeable membrane From dilute solution to concentrated solution Against the concentration gradient without any membrane Only when the applied pressure is less than osmotic pressure The boiling point of a 0.2 m aqueous solution of a non-volatile solute is 100.104 C . The boiling point of a 0.2 m aqueous solution of MgCl 2 (assume 100 % ionization) will be: 100.312 °C 100.208 °C 100.104 °C 100.520 °C Which of the following will have the same boiling point as 0.1 M Na 2SO 4 solution (assuming 100 % dissociation)? 0.1 M BaCl 2 0.1 M NaCl 0.3 M Glucose Both 0.1 M BaCl 2 and 0.3 M Glucose What is the boiling point of a solution containing 12.5 ,g of a non-electrolyte substance in 175 ,g of water? (Molar mass of substance = 342 ,g/mol , K b = 0.52 ,K ,kg ,mol -1 ) 100.11 C 100.05 C 100.22 C 99.89 C The freezing point of benzene is 5.5 C . A solution of 1.5 ,g of a non-volatile solute in 100 ,g of benzene freezes at 4.9 C . Calculate the molar mass of the solute. ( K f for benzene = 5.12 ,K ,kg ,mol -1 ) 128 g/mol 256 g/mol 64 g/mol 150 g/mol The osmotic pressure of a solution containing 4.0 ,g of a polymer in 1 ,L of solution at 27 C is 1.245 10 -3 ,atm . The molar mass of the polymer is ( R = 0.0821 ,L ,atm ,K -1 ,mol -1 ): 7.91 10 4 ,g/mol 3.12 10 4 ,g/mol 1.56 10 5 ,g/mol 4.00 10 3 ,g/mol The boiling point of a 0.01 ,M aqueous solution of BaCl 2 is 100.015 C . What is the boiling point of a 0.01 ,M glucose solution at the same pressure? (Assume BaCl 2 is 100 % dissociated) 100.005 C 100.015 C 100.045 C 100.010 C What happens to the value of the cryoscopic constant ( K f ) when the molar mass of the solvent increases, assuming other factors like freezing point and heat of fusion are constant? Increases Decreases Remains the same First increases then decreases The molal freezing point depression constant ( K f ) for water is 1.86 K kg mol -1 . If 342 g of cane sugar ( C 12 H 22 O 11 ) is dissolved in 1000 g of water, the solution will freeze at: -1.86 C 1.86 C -3.72 C 0 C