Assignments Class 12 Chemistry Solutions

Please refer to Assignments Class 12 Chemistry Solutions Chapter 2 with solved questions and answers. We have provided Class 12 Chemistry Assignments for all chapters on our website. These problems and solutions for Chapter 2 Solutions Class 12 Chemistry have been prepared as per the latest syllabus and books issued for the current academic year. Learn these solved important questions to get more marks in your class tests and examinations.

Solutions Assignments Class 12 Chemistry

Question. Which of the following units is useful in relating concentration of solution with its vapour pressure?
(A) Mole fraction
(B) Parts per million
(C) Mass percentage
(D) Molality

Question. When 1 mole of benzene is mixed with 1 mole of toluene the vapour will contain: (Given: vapour of benzene = 12.8kPa and vapour pressure of toluene = 3.85 kPa). 
(A) equal amount of benzene and toluene as it forms an ideal solution
(B) unequal amount of benzene and toluene as it forms a non ideal solution
(C) higher percentage of benzene
(D) higher percentage of toluene

Question. KH value for Ar(g), CO₂(g), HCHO(g) and CH4(g) are 4.039, 1.67, 1.83 × 10^–5, and 0.143, respectively.Arrange these gases in the order of their increasing solubility
(A) HCHO < CH₄ < CO₂ < Ar
(B) HCHO < CO₂ < CH₄ < Ar
(C) Ar < CO₂ < CH₄ < HCHO
(D) Ar < CH₄ < CO₂ < HCHO

Question. A beaker contains a solution of substance ‘A’.Precipitation of substance ‘A’ takes place when small amount of ‘A’ is added to the solution. The solution is _________.
(A) saturated
(B) supersaturated
(C) unsaturated
(D) concentrated

Question. At equilibrium the rate of dissolution of a solid solute in a volatile liquid solvent is __________.
(A) less than the rate of crystallisation
(B) greater than the rate of crystallisation
(C) equal to the rate of crystallisation
(D) zero

Question.  Which of the following solutions in water has highest boiling point?
(A) 1 M NaCl
(B) 1 M MgCl₂
(C) 1 M urea
(C) 1 M glucose

Question. Which of the following aqueous solutions should have the highest boiling point?
(A) 1.0 M NaOH
(B) 1.0 M Na₂SO₄
(C) 1.0 M NH₄NO₃
(D) 1.0 M KNO₃

Question. A molar solution is one that contains one mole of a solute in
(A) 1000 g of the solvent
(B) one litre of the solvent
(C) one litre of the solution
(D) 22.4 litre of the solution

Question. In which mode of expression, the concentration of a solution remains independent of temperature?
(A) Molarity
(B) Normality
(C) Formality
(D) Molality

Question. Value of Henry’s constant KH is ________________.
(A) Increases with increase in temperature.
(B) Decreases with increase in temperature
(C) Remains constant
(D) First increases then decreases.

Question. For a dilute solution, Raoult’s law states that
(A) The lowering of vapour pressure is equal to the mole fraction of solute.
(B) The relative lowering of vapour pressure is equal to the mole fraction of solute.
(C) The relative lowering of vapour pressure is proportional to the amount of solute in solution.
(D) The vapour pressure of the solution is equal to the mole fraction of the solute.

Question. Relative lowering of vapour pressure is a colligative property because _________ .
(A) It depends on number of particles of electrolyte solute in solution and does not depend on the nature of the solute particles.
(B) It depends on the concentration of a non electrolyte solute in solution as well as on the nature of the solute molecules.
(C) Is depends on the concentration of an electrolyte or non-electrolyte solute is solution as well on the nature of solute molecules.
(D) None of the above

Question. The unit of ebullioscopic constant is:
(A) K kg mol^-1 or K (molality)^-1
(B) mol kg^-1 K^-1 or K^-1 (molality)
(C) kg mol-1 K^-1 or K- (molality)^-1
(D) K mol kg^-1 or K (molality)

Question. The increase in the temperature of the aqueous solution will result in its
(A) Molarity to increase
(B) Molarity to decrease
(C) Mole fraction to increase
(D) Mass % to increase

Question. Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?
(A) Methanol and acetone.
(B) Chloroform and acetone.
(C) Nitric acid and water.
(D) Phenol and aniline.

Question. If two liquids A and B form minimum boiling azeotrope at some specific composition, then.
(A) A–B interactions are stronger than those between A–A or B–B.
(B) vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution.
(C) vapour pressure of solution decreases because less number of molecules of only one of the liquids escape from the solution.
(D) A–B interactions are weaker than those between A–A or B–B.

Question. Consider the figure and mark the correct option.

(A) Water will move from side (A) to side (B) if pressure lower than osmotic pressure is applied on piston (B).
(B) Water will move from side (B) to side (A) if pressure greater than osmotic pressure is applied on piston (B).
(C) Water will move from side (B) to side (A) if pressure equal to osmotic pressure is applied on piston (B).
(D) Water will move from side (A) to side (B) if pressure equal to osmotic pressure is applied on piston (A).

Question. If two liquids A and B form minimum boiling azeotrope at some specific composition then_________.
(A) A–B interactions are stronger than those between A–A or B–B.
(B) Vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution.
(C) Vapour pressure of solution decreases because less number of molecules of only one of the liquids escape from the solution.
(D) A–B interactions are weaker than those between A–A or B–B.

ASSERTION AND REASON BASED MCQs 

Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
(A) Both A and R are true and R is the correct explanation of A
(B) Both A and R are true but R is NOT the correct explanation of A
(C) A is true but R is false
(D) A is false and R is True

Question. Assertion (A): Elevation in boiling point is a colligative property.
Reason (R): Elevation in boiling point is directly proportional to molarity. 

Question. Assertion (A): Molarity of a solution changes with temperature.
Reason (R): Molarity is dependent on volume of solution.

Question. Assertion (A): 0.1 M solution of KCl has great osmotic pressure than 0.1 M solution of glucose at same temperature.
Reason (R): In solution KCl dissociates to produce more number of particles.

Question. Assertion (A): An ideal solution obeys Henry’s law.
Reason (R): In an ideal solution, solute-solute as well as solvent-solvent interactions are similar to solutesolvent interaction. 

Question. Assertion (A): Molarity of 0.1 N solution of HCl is 0.1 M.
Reason (R): Normality and molarity of a solution are always equal.

Question. Assertion (A): Dimethyl ether is less volatile than ethyl alcohol.
Reason (R): Dimethyl ether has greater vapour pressure than ethyl alcohol.

Question. Assertion (A): Molarity of a solution in liquid state changes with temperature.
Reason (R): The volume of a solution changes with change in temperature.

Question. Assertion (A): Vapour pressure increase with increase in temperature.
Reason (R): With increase in temperature, more molecules of the liquid can go into vapour phase.

Question. Assertion (A): A molar solution is more concentrated than molal solution.
Reason (R): A molar solution contains one mole of solute in 1000 mL of solution.

CASE-BASED MCQs

I. Read the passage given below and answer the following questions:

Scuba apparatus includes a tank of compressed air toted by the diver on his or her back, a hose for carrying air to a mouthpiece, a face mask that covers the eyes and nose, regulators that control air flow, and gauges that indicate depth and how much air remains in the tank. A diver who stays down too long, swims too deep, or comes up too fast can end up with a condition called “the bends.” In this case, bubbles of gas in the blood can cause intense pain, even death. In these following questions a statement of assertion followed by a statement of reason is given.

Choose the correct answer out of the following choices.
(A) Assertion and Reason both are correct statements and Reason is correct explanation for Assertion.
(B) Assertion and Reason both are correct statements but Reason is not correct explanation for Assertion.
(C) Assertion is correct statement but Reason is wrong statement.
(D) Assertion is wrong statement but Reason is correct statement.

Question. Assertion: Bends is caused due to formation of nitrogen bubbles in the blood of scuba divers which blocks the capillaries.
Reason: Underwater high pressure increases solubility of gases in blood, while as pressure gradually decreases moving towards the surface,gases are released and nitrogen bubbles are formed in blood.

Question. Assertion: Scuba divers may face a medical condition called ‘bends’.
Reason: ‘Bends’ can be explained with the help of Henry’s law as it links the partial pressure of gas to that of its mole fraction.

Question. Assertion: Anoxia is a condition experienced by climbers which makes them suddenly agile and unable to think clearly.
Reason: At high altitudes the partial pressure of oxygen is less than that at the ground level.

Question. Assertion: Soft drinks and soda water bottles are sealed under high pressure.
Reason: High pressure maintains the taste and texture of the soft drinks.

II. Read the passage given below and answer the following questions:

Raoult’s law states that for a solution of volatile liquids, the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution. Dalton’s law of partial pressure states that the total pressure (ptotal) over the solution phase in the container will be the sum of the partial pressures of the components of the solution and is given as:
P_total = P₁ +P₂ 

Question. In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl₂ solution is _____________.
(A) the same
(B) about twice
(C) about three times
(D) about six times

Question. What type of deviation from Raoult’s law does the above graph represent ?
(A) First positive then negative
(B) Negative deviation
(C) Positive deviation
(D) First negative then positive

Question. Which of the following aqueous solutions should have the highest boiling point ?
(A) 1.0 M NaOH
(B) 1.0 M Na₂SO₄
(C) 1.0 M NH₄NO₃
(D) 1.0 M KNO₃

Question. A solution of two liquids boils at a temperature more than the boiling point of either of them. What type of deviation will be shown by the solution formed in terms of Raoult’s law ?
(A) Negative deviation
(B) Positive deviation
(C) First positive then negative
(D) First negative then positive

III. Read the passage given below and answer the following questions:

Boiling point or freezing point of liquid solution would be affected by the dissolved solids in the liquid phase. A soluble solid in solution has the effect of raising its boiling point and depressing its freezing point. The addition of non-volatile substances to a solvent decreases the vapor pressure and the added solute particles affect the formation of pure solvent crystals.
According to many researches the decrease in freezing point directly correlated to the concentration of solutes dissolved in the solvent. This phenomenon is expressed as freezing point depression and it is useful for several applications such as freeze concentration of liquid food and to find the molar mass of an unknown solute in the solution. Freeze concentration is a high quality liquid food concentration method where water is removed by forming ice crystals. This is done by cooling the liquid food below the freezing point of the solution. The freezing point depression is referred as a colligative property and it is proportional to the molar concentration of the solution (m), along with vapor pressure lowering, boiling point elevation, and osmotic pressure. These are physical characteristics of solutions that depend only on the identity of the solvent and the concentration of the solute. The characters are not depending on the solute’s identity.

Question. When a non volatile solid is added to pure water it will:
(a) boil above 100°C and freeze above 0°C
(b) boil below 100°C and freeze above 0°C
(c) boil above 100°C and freeze below 0°C
(d) boil below 100°C and freeze below 0°C

Question. Colligative properties are:
(a) dependent only on the concentration of the solute and independent of the solvent’s and solute’s identity.
(b) dependent only on the identity of the solute and the concentration of the solute and independent of the solvent’s identity.
(c) dependent on the identity of the solvent and solute and thus on the concentration of the solute.
(d) dependent only on the identity of the solvent and the concentration of the solute and independent of the solute’s identity.

Question. Assume three samples of juices A, B and C have glucose as the only sugar present in them.The concentration of sample A, B and C are 0.1M,.5M and 0.2 M respectively. Freezing point will be highest for the fruit juice:
(a) A
(b) B
(c) C
(d) All have same freezing point

Question. Identify which of the following is a colligative property:
(A) freezing point
(B) boiling point
(C) osmotic pressure
(D) all of the above

STATEMENT TYPE QUESTIONS

Question. On the basis of information given below mark the correct option.
(i) In bromoethane and chloroethane mixture intermolecular interactions of A-A and B-B type are nearly same as A-B type interactions.
(ii) In ethanol and acetone mixture A-A or B-B type intermolecular interactions are stronger than A-B type interactions.
(iii) In chloroform and acetone mixture A-A or B-B type intermolecular interactions are weaker than A-B type interactions.
(a) Solution (ii) and (iii) will follow Raoult’s law.
(b) Solution (i) will follow Raoult’s law.
(c) Solution (ii) will show negative deviation from Raoult’s law.
(d) Solution (iii) will show positive deviation from Raoult’s law.

Question. Molarity and molality of a solution of NaOH is calculated.If now temperature of the solution is increased then which of the following statement(s) is/are correct ?
(i) Molarity of solution decreases
(ii) Molality of the solution increases
(a) Both statements are correct
(b) Statement (i) is correct only
(c) Statement (ii) is correct only
(d) Both statements are incorrect.

Question. Read the following statements carefully and choose the correct option.
(i) Different gases have different KH values at the same temperature.
(ii) Higher the value of KH at a given temperature, lower is the solubility of the nature of gas in the liquid.
(iii) KH is a function of the nature of the gas.
(iv) Solubility of gases increases with increase of temperature.
(a) (i), (ii) and (iv) are correct.
(b) (ii) and (iv) are correct.
(c) (i), (ii) and (iii) are correct.
(d) (i) and (iv) are correct

Question. Which observation(s) reflect(s) colligative properties?
(i) A 0.5 m NaBr solution has a higher vapour pressure than a 0.5 m BaCl2 solution at the same temperature
(ii) Pure water freezes at the higher temperature than pure methanol
(iii) a 0.1 m NaOH solution freezes at a lower temperature than pure water
Choose the correct answer from the codes given below
(a) (i), (ii) and (iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (i) and (iii)

Question. Read the following statements and choose the correct option.
(i) Polar solutes dissolve in a polar solvent.
(ii) Polar solutes dissolve in a non-polar solvent.
(iii) Non-polar solutes dissolve in a non-polar solvent.
(iv) Non-polar solutes dissolve in a polar solvent.
(a) (i) and (ii) are correct.
(b) (i), (ii) and (iii) are correct.
(c) (i) and (iii) are correct.
(d) (ii) and (iv) are correct.

Question. Study the given statements and choose the correct option.
(i) 3.62 mass percentage of sodium hypochlorite in water is used as commercial bleaching solution.
(ii) 35% volume percentage of ethylene glycol is used as an antifreeze (as coolent in car engines).
(iii) Concentration of dissolved oxygen in a litre of sea water is 5.8 ppm.
(a) Statements (i) and (ii) are correct
(b) Statements (i) and (iii) are correct
(c) Statements (ii) and (iii) are correct
(d) Statements (i),(ii) and (iii) are correct

Question. Read the following statements carefully and choose the correct option
(i) Osmotic pressure is not a colligative property.
(ii) For dilute solutions, osmotic pressure is proportional to the molarity, C of the solution at a given temperature T.
(iii) During osmosis ,solvent molecules always flow from higher concentration to lower concentration of solution.
(iv) The osmotic pressure has been found to depend on the concentration of the solution
(a) (i), (ii) and (iv) are correct
(b) (ii) and (iv) are correct
(c) (iii), and (iv) are correct
(d) (i), (ii) and (iii) are correct

Question. Read the following statements carefully and choose the correct option
(i) The vapour pressure of a liquid decreases with increase of temperature.
(ii) The liquid boils at the temperature at which its vapour pressure is equal to the atmospheric pressure.
(iii) Vapour pressure of the solvent decreases in the presence of non-volatile solute.
(iv) Vapour pressure of the pure solvent and solution is a function of temperature.
(a) (i), (ii) and (iv) are correct
(b) (i), (iii), and (iv) are correct
(c) (ii), (iii), and (iv) are correct
(d) (i), (ii) and (iii) are correct

Question. “If temperature increases solubility of gas decreases”. For this situation which of the following statement(s) is/are correct ?
(i) Reaction is endothermic
(ii) Le-chatelier’s principle can be applied
(a) Statement (i) and (ii) both are correct
(b) Statement (i) is correct only
(c) Statement (ii) is correct only
(d) Both statement(s) (i) and (ii) are incorrect 

MATCHING TYPE QUESTIONS

Question. Match the laws given in the Column-I with expression given in Column-II.

(a) A – (r), B – (t), C – (s), D – (p), E – (q)
(b) A – (t), B – (r), C – (q), D – (s), E – (p)
(c) A – (p), B – (t), C – (r), D – (q), E – (s)
(d) A – (s), B – (p), C – (q), D – (r), E – (t)

Question. Match the columns

Column-I                                        Column-II
(A) Na-Hg Amalgam                     (p) gas – solid
(B) H2 in Pd                                 (q) gas – liquid
(C) Camphor in nitrogen gas         (r) liquid – solid
(D) Oxygen dissolved in water       (s) solid – gas
(a) A – (q), B – (s), C – (r), D – (p)
(b) A – (t), B – (p), C – (q), D – (s)
(c) A – (r), B – (p), C – (s), D – (q)
(d) A – (s), B – (q), C – (p), D – (p)

Question. Match the Column I, II & III and choose the correct option.

Column-I                                         Column-II                   Column-III
(A) Gaseous solutions                     (p) Solid-liquid           (h) Copper dissolved in gold
(B) Liquid solutions                        (q) Solid-solid             (i) Chloroform mixed with nitrogen
(C) Solid solutions                         (r) Liquid-gas              (j) Common salt  dissolved in water
(a) (A) – (r) – (h), (B) – (r) – (i), (C) – (p) – (j)
(b) (A) – (r) – (i), (B) – (p) – (j), (C) – (q) – (h)
(c) (A) – (r) – (j), (B) – (p) – (h), (C) – (q) – (i)
(d) (A) – (r) – (j), (B) – (q) – (i), (C) – (p) – (h)

Question. Match the columns

Column -I                            Column-II
(A) Mass percentage           (p) Medicine and pharmacy
(B) Mass by volume            (q) Concentration of pollutants in water
(C) ppm                              (r) Industrial chemical application
(D) Volume percentage         (s) Liquid solutions
(a) A – (q), B – (p), C – (s), D – (r)
(b) A – (s), B – (r), C – (p), D – (q)
(c) A – (r), B – (q), C – (s), D – (p)
(d) A – (r), B – (p), C – (q), D – (s)

Question. Match the columns

(a) A – (s), B – (r), C – (p), D – (q)
(b) A – (r), B – (p), C – (s), D – (q)
(c) A – (r), B – (s), C – (q), D – (p)
(d) A – (q), B – (p), C – (r), D – (s) 

ASSERTION-REASON TYPE QUESTIONS

Directions : Each of these questions contain two statements,Assertion and Reason. Each of these questions also has four alternative choices, only one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

Question. Assertion : Azeotropic mixtures are formed only by non-ideal solutions and they may have boiling points either greater than both the components or less than both the components. 
Reason : The composition of the vapour phase is same as that of the liquid phase of an azeotropic mixture.

Question. Assertion : If one component of a solution obeys Raoult’s law over a certain range of composition, the other component will not obey Henry’s law in that range. 
Reason : Raoult’s law is a special case of Henry’s law.

Question. Assertion : When a solution is separated from the pure solvent by a semi- permeable membrane, the solvent molecules pass through it from pure solvent side to the solution side       
Reason : Diffusion of solvent occurs from a region of high concentration solution to a region of low concentration solution.

Question. Assertion : Molarity of a solution in liquid state changes with temperature. 
Reason : The volume of a solution changes with change in temperature.

Question. Assertion : When NaCl is added to water a depression in freezing point is observed.   
Reason : The lowering of vapour pressure of a solution causes depression in the freezing point.

Question. Assertion : If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., ps > po. 
Reason : In the presence of a more volatile liquid solute,only the solute will form the vapours and solvent will not.

Question. Assertion : When methyl alcohol is added to water, boiling point of water increases. 
Reason : When a volatile solute is added to a volatile solvent elevation in boiling point is observed.

CRITICAL THINKING TYPE QUESTIONS

Question. If two liquids A and B form minimum boiling azeotrope at some specific composition then _______.
(a) A – B interactions are stronger than those between A – A or B – B
(b) vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution.
(c) vapour pressure of solution decreases because less number of molecules of only one of the liquids escape from the solution
(d) A – B interactions are weaker than those between A – A or B – B

Question. Equal masses of methane and oxygen are mixed in an empty container at 25°C. The fraction of the total pressure exerted by oxygen is
(a) 1/2
(b) 2/3
(c) 1/3 × 273/298
(d) 1/3

Question. The normality of orthophosphoric acid having purity of 70 % by weight and specific gravity 1.54 is
(a) 11 N
(b) 22 N
(c) 33 N
(d) 44 N

Question. KH value for Ar(g), CO₂(g), HCHO (g) and CH₄(g) are 40.39,1.67, 1.83 × 10^–5 and 0.413 respectively.
Arrange these gases in the order of their increasing solubility.
(a) HCHO < CH₄ < CO₂ < Ar
(b) HCHO < CO₂ < CH₄ < Ar
(c) Ar < CO₂ < CH₄ < HCHO
(d) Ar < CH₄ < CO₂ < HCHO

Question. What is the ratio of no. of moles of nitrogen to that of oxygen in a container of 5 litre at atmospheric pressure?
(a) 1 : 1.71
(b) 1 : 2
(c) 2 : 1
(d) 1 : 24

Question. Consider a and b are two components of a liquid mixture,their corresponding vapour pressure (mmHg) are respectively 450 and 700 in pure states and total pressure given is 600. Then corresponding composition in liquid phase will be
(a) 0.4, 0.6
(b) 0.5, 0.5
(a) 0.6, 0.4
(d) 0.3, 0.7

Question. For a dilute solution containing 2.5 g of a non-volatile nonelectrolyte solute in 100 g of water, the elevation in boiling point at 1 atm pressure is 2°C. Assuming concentration of solute is much lower than the concentration of solvent, the vapour pressure (mm of Hg) of the solution is (take Kb = 0.76 K kg mol^–1)
(a) 724
(b) 740
(c) 736
(d) 718

Question. Which will form maximum boiling point azeotrope
(a) HNO₃ + H₂O solution
(b) C₂H₅OH + H₂O solution
(c) C₆H₆ + C₆H₅CH₃ solution
(d) None of these

Question. Chloroform and acetone are added to each other, Raoult’s law shows negative deviation.what does this suggests ?
(a) Exothermic reaction
(b) Endothermic reaction
(c) Zero change in enthalpy
(d) None of these

Question. When a gas is bubbled through water at 298 K, a very dilute solution of the gas is obtained. Henry’s law constant for the gas at 298 K is 100 kbar. If the gas exerts a partial pressure of 1 bar, the number of millimoles of the gas dissolved in one litre of water is
(a) 0.555
(b) 5.55
(c) 0.0555
(d) 55.5

Question. Which of the following statements, regarding the mole fraction (x) of a component in solution, is incorrect?
(a) 0 ≤ x ≤1
(b) x ≤1
(c) x is always non-negative
(d) None of these

Question. Which one of the following gases has the lowest value of Henry’s law constant?
(a) N₂
(b) He
(c) H₂
(d) CO₂

Question. Someone has added a non electrolyte solid to the pure liquid but forgot that among which of the two beakers he has added that solid. This problem can be solved by checking
(a) relative lower in vapour pressure
(b) elevation in boiling point
(c) depression in Freezing point
(d) all above

Question. An 1% solution of KCl (I), NaCl (II), BaCl2 (III) and urea (IV) have their osmotic pressure at the same temperature in the ascending order (molar masses of NaCl, KCl,BaCl₂ and urea are respectively 58.5, 74.5, 208.4 and 60 g mole^–1). Assume 100% ionization of the electrolytes at this temperature
(a) I < III < II < IV
(b) III < I < II < IV
(c) I < II < III < IV
(d) III < IV < I < II

Question. Vapour pressure of benzene at 30°C is 121.8 mm. When 15g of a non-volatile solute is dissolved in 250 g of benzene, its vapour pressure is decreased to 120.2 mm. The molecular weight of the solute is
(a) 35.67 g
(b) 356.7 g
(c) 432.8 g
(d) 502.7 g

Question. The difference between the boiling point and freezing point of an aqueous solution containing sucrose (molecular wt = 342 g mole^–1) in 100 g of water is 105°C. If Kf and Kb of water are 1.86 and 0.51 K kg mol^–1 respectively, the weight of sucrose in the solution is about
(a) 34.2 g
(b) 342 g
(c) 7.2 g
(d) 72 g

Question. At 300 K the vapour pressure of an ideal solution containing 1 mole of liquid A and 2 moles of liquid B is 500 mm of Hg.The vapour pressure of the solution increases by 25 mm of Hg, if one more mole of B is added to the above ideal solution at 300 K. Then the vapour pressure of A in its pure state is
(a) 300 mm of Hg
(b) 400 mm of Hg
(c) 500 mm of Hg
(d) 600 mm of Hg

Question. The boiling point of 0.2 mol kg^–1 solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case ?
(a) Molecular mass of X is greater than the molecular mass of Y.
(b) Molecular mass of X is less than the molecular mass of Y.
(c) Y is undergoing dissociation in water while X undergoes no change.
(d) X is undergoing dissociation in water.

Question. The vapour pressure of a solvent decreases by 10 mm of Hg when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of Hg ?
(a) 0.8
(b) 0.6
(c) 0.4
(d) 0.2

Question. What is the freezing point of a solution containing 8.1 g HBr in 100 g water assuming the acid to be 90% ionised ? (Kf for water = 1.86 K kg mol^–1) :
(a) 0.85°K
(b) – 3.53°K
(c) 0°K
(d) – 0.35°K

Question. 1 g of a non-volatile, non-electrolyte solute of molar mass 250 g/mol was dissolved in 51.2 g of benzene. If the freezing point depression constant Kf of benzene is 5.12 kg K mol^–1. The freezing point of benzene is lowered by
(a) 0.3 K
(b) 0.5 K
(c) 0.2 K
(d) 0.4 K 

Question. If the elevation in boiling point of a solution of non-volatile, non-electrolytic and non-associating solute in a solvent (Kb = x K kg mol^–1) is y K, then the depression in freezing point of solution of same concentration would be (Kf of the solvent = z K kg mol^–1)
(a) 2xz/y
(b) yz/x
(c) xz/y
(d) yz/2x