JEE Chemistry Solutions MCQs Set B

Question: The vapour pressure of the solution at a given temperature is found to be  ________ than the vapour pressure of the pure solvent at the same temperature

• a) lower
• b) higher
• c) equal
• d) can't calculate

Answer: lower

Question: The decrease in the vapour pressure of solvent depends on the

• a) quantity of non-volatile solute present in the solution
• b) nature of non-volatile solute present in the solution
• c) molar mass of non-volatile solute present in the solution
• d) physical state of non-volatile solute present in the solution

Answer: quantity of non-volatile solute present in the solution

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:   The vapour pressure of two liquids ‘P’ and ‘Q’ are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mole of Q would be

• a) 72 torr
• b) 140 torr
• c) 20 torr
• d) 68 torr

Answer: 72 torr

Question: 18 g of glucose (C₆H₁₂O₆) is added to 178.2 g of water. The vapour pressure of water for this aqueous solution is

• a) 752.40 torr
• b) 7.60 torr
• c) 76.00 torr
• d) 759.00 torr

Answer: 752.40 torr

Question:  P_A and P_B are the vapour pressure of pure liquid components, A and B, respectively of an ideal binary solution. If X_A represents the mole fraction of component A, the total pressure of the solution will be.

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm Hg at 300 K. The vapour pressure of propyl alcohol is 200 mm Hg. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure (in mm Hg) at the same temperature will be

• a) 350
• b) 700
• c) 360
• d) 300

Answer: 350

Question:  Two liquids X and Y form an ideal solution. At 300 K, vapour pressure of the solution containing 1 mol of X and 3 mol of Y is 550 mm Hg. At the same temperature, if 1 mol of Y is further added to this solution, vapour pressure of the solution increases by 10 mm Hg. Vapour pressure ( in mm Hg) of X and Y in their pure states will be, respectively

• a) 400 and 600
• b) 200 and 300
• c) 300 and 400
• d) 500 and 600

Answer: 400 and 600

Question: The vapour pressure of two liquids X and Y are 80 and 60 torr respectively. The total vapour pressure of the ideal solution obtained by mixing 3 moles of X and 2 moles of Y would be

• a) 72 Torr
• b) 140 Torr
• c) 68 Torr
• d) 48 Torr

Answer: 72 Torr

Question: The vapour pressure of pure benzene and toluene at a particular temperature are 100 mm and 50 mm respectively. Then the mole fraction of benzene in vapour phase in contact with equimolar solution of benzene and toluene is

• a) 0.67
• b) 0.33
• c) 0.75
• d) 0.50

Answer:  0.67

Question: A solution containing components A and B follows Raoult's law when

• a) A – B attraction force remains same as A–A and B –B
• b) volume of solution is different from sum of volume of solute and solvent
• c) A – B attraction force is less than A – A and B – B
• d) A – B attraction force is greater than A – A and B – B

Answer: A – B attraction force remains same as A–A and B –B

Question: Relation between partial pressure and mole fraction is stated by

• a) Raoult’s law
• b) Avogadro law
• c) Graham’s law
• d) Le-Chatelier

Answer: Raoult’s law

Question: Which one of the following is not correct for an ideal solution?

• a) All are correct
• b) It must obey Raoult’s law
• c)

  

• d)

  

Answer: All are correct

Question: An ideal solution is formed when its components

• a) Both
• b) have no volume change on mixing
• c) have no enthalpy change on mixing
• d) None of these

Answer: Both

Question: All form ideal solution except

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Which one of the following is non-ideal solution

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Mixtures of ethanol and acetone show positive deviation. The reason is

• a) In pure ethanol, molecules are hydrogen bonded
• b) In pure acetone, molecules are hydrogen bonded
• c) In both molecules are hydrogen bonded
• d) None of these

Answer: In pure ethanol, molecules are hydrogen bonded

Question: A mixture of components A and B will show –ve deviation when

• a) A–B interaction is stronger than A–A and B–B interactions.
• b) A–B interaction is weaker than A–A and B– B interactions
• c) Both
• d) None of these

Answer: A–B interaction is stronger than A–A and B–B interactions.

Question: Which of the following liquid pairs shows a positive deviation from Raoult’s law ?

• a) Benzene - Methanol
• b) Water - Nitric acid
• c) Water - Hydrochloric acid
• d) Acetone - Chloroform

Answer: Benzene - Methanol

Question:  A solution of acetone in ethanol

• a) shows a positive deviation from Raoult’s law
• b) behaves like a non ideal solution
• c) obeys Raoult’s law
• d) shows a negative deviation from Raoult’s law

Answer: shows a positive deviation from Raoult’s law

Question: Negative deviation from Raoult’s law is observed in which one of the following binary liquid mixtures?

• a) Ethanol and acetone
• b) Benzene and toluene
• c) Acetone and chloroform
• d) Chloroethane and bromoethane

Answer: Ethanol and acetone

Question: Which one of the following binary liquid systems shows positive deviation from Raoult’s law?

• a) Carbon disulphide-acetone
• b) Phenol-aniline
• c) Chloroform-acetone
• d) Benzene-toluene

Answer: Carbon disulphide-acetone

Question: A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

• a) The solution is non-ideal, showing positive deviation from Raoult’s Law.
• b) n-heptane shows positive deviation while ethanol shows negative deviation from Raoult’s Law
• c) The solution formed is an ideal solution
• d) The solution is non-ideal, showing negative deviation from Raoult’s Law

Answer:  The solution is non-ideal, showing positive deviation from Raoult’s Law.

Question: Which one is not equal to zero for an ideal solution

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: A mixture of two completely miscible non-ideal liquids which distill as such without change in its composition at a constant temperature as though it were a pure liquid. This mixture is known as

• a) azeotropic mixture
• b) ideal mixture
• c) binary liquid mixture
• d) eutectic mixture

Answer: azeotropic mixture

Question: The azeotropic mixture of water (b.p.100°C) and HCl (b.p.85°C) boils at 108.5°C. When this mixture is distilled it is possible to obtain

• a) neither HCl nor H₂O in their pure states
• b) pure water as well as pure HCl
• c) pure water
• d) pure HCl

Answer: neither HCl nor H₂O in their pure states

Question:  The system that forms maximum boiling azeotrope is

• a) acetone – chloroform
• b) benzene – toluene
• c) carbondisulphide – acetone
• d) n-hexane – n-heptane

Answer: acetone – chloroform

Question: Which one of the following binary mixtures forms an azeotrope with minimum boiling point type?

• a) acetone-ethanol
• b) benzene-toluene
• c) n-hexane-n-heptane
• d) None of these

Answer: acetone-ethanol

Question: On the basis of information given below mark the correct option. Information: On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.

• a) At specific composition methanol-acetone mixture forms boiling azeotrope and will show positive deviation from Raoult’s law.
• b) At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show negative deviation from Raoult’s law.
• c) At specific composition methanol-acetone mixture will form boiling azeotrope and will show negative deviation from Raoult’s law.
• d) None of these

Answer: At specific composition methanol-acetone mixture forms boiling azeotrope and will show positive deviation from Raoult’s law.

Question: According to Raoult's law, relative lowering of vapour pressure for a solution is equal to

• a) mole fraction of solute
• b) moles of solute
• c) moles of solvent
• d) mole fraction of solvent

Answer: mole fraction of solute

Question: The relative lowering of the vapour pressure is equal to the ratio between the number of

• a) solute molecules to the total molecules in the solution
• b) solute molecules to the solvent molecules
• c) solvent molecules to the total molecules in the solution
• d) solvent molecules to the total number of ions of the solute

Answer: solute molecules to the total molecules in the solution

Question:  Vapour pressure of benzene at 30°C is 121.8 mm Hg. When 15 g of a non volatile solute is dissolved in 250 g of benzene its vapour pressure decreased to 120.2 mm Hg. The molecular weight of the solute (Mo. wt. of solvent = 78)

• a) 356.2
• b) 530.1
• c) 456.8
• d) 656.7

Answer: 356.2

Question: The value of P° for benzene is 640 mm of Hg. The vapour pressure of solution containing 2.5gm substance in 39gm. benzene is 600mm of Hg the molecular mass of X is

• a) 75
• b) 130
• c) 65.25
• d) 40

Answer: 75

Question: The vapour pressure at a given temperature of an ideal solution containing 0.2 mol of a non-volatile solute and 0.8 mol of solvent is 60 mm of Hg. The vapour pressure of the pure solvent at the same temperature is

• a) 75 mm of Hg
• b) 150 mm of Hg
• c) 60 mm of Hg
• d) 120 mm of Hg

Answer: 75 mm of Hg

Question: 12 g of a nonvolatile solute dissolved in 108 g of water produces the relative lowering of vapour pressure of 0.1. The molecular mass of the solute is

• a) 20
• b) 80
• c) 60
• d) 40

Answer: 20

Question: The amount of solute (molar mass 60 g.mol^–1) that must be added to 180 g of water so that the vapour pressure of water is lowered by 10% is

• a) 60 g
• b) 12 g
• c) 30 g
• d) 120 g

Answer: 60 g

Question: The vapour pressure of water at 20°C is 17.5 mm Hg. If 18 g of glucose (C₆H₁₂O₆) is added to 178.2 g of water at 20°C, the vapour pressure of the resulting solution will be

• a) 17.325 mm Hg
• b) 16.500 mm Hg
• c) 15.750 mm Hg
• d) 17.500 mm Hg

Answer: 17.325 mm Hg

Question: Which one of the following is a colligative property ?

• a) Osmotic pressure
• b) Boiling point
• c) Vapour pressure
• d) Freezing point

Answer: Osmotic pressure

Question: Which one of the following aqueous solutions will exihibit highest boiling point ?

• a) 0.01 M Na₂SO₄
• b) 0.015 M urea
• c) 0.01 M KNO₃
• d) None of these

Answer:  0.01 M Na₂SO₄

Question: The rise in the boiling point of a solution containing 1.8 g of glucose in 100 g of solvent is 0.1°C. The molal elevation constant of the liquid is

• a) 1 K/m
• b) 0.01 K/m
• c) 0.1 K/m
• d) 10 K/m

Answer: 1 K/m

Question: For an electrolyte, elevation of B.P. is directly proportional to

• a) molality
• b) All of these
• c) molarity
• d) mole fraction

Answer: molality

Question: Which of the following aqueous solution has minimum freezing point ?

• a) 0.01 m NaCl
• b) 0.005 m MgI₂
• c) 0.005 m C₂H₅OH
• d) None of these

Answer: 0.01 m NaCl

Question:  1.00 g of a non-electrolyte solute (molar mass 250 g 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

• a) 0.4 K
• b) 0.3 K
• c) 0.5 K
• d) 0.2

Answer: 0.4 K

Question: In a 0.2 molal aqueous solution of a weak acid HX the degree of ionization is 0.3. Taking kf for water as 1.85, the freezing point of the solution will be nearest to

• a) – 0.481ºC
• b) – 0.260ºC
• c) – 0.360ºC
• d) + 0.481ºC

Answer:  – 0.481ºC

Question: The molecular weight of benzoic acid in benzene as determined by depression in freezing point method corresponds to

• a) dimerization of benzoic acid
• b) ionization of benzoic acid
• c) trimerization of benzoic acid.
• d) solvation of benzoic acid

Answer: dimerization of benzoic acid

Question: A 0.5 molal solution of ethylene glycol in water is used as coolant in a car. If the freezing point constant of water be 1.86°C per mole, the mixture shall freeze at

• a) –0.93°C
• b) –1.86°C
• c) 0.93°C
• d) 1.86°C

Answer: –0.93°C

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The freezing point of 1% solution of lead nitrate in water will

• a) below 0°C
• b) 1°C
• c) 2°C
• d) 0°C

Answer: below 0°C

Question: A solution containing 1.8 g of a compound (empirical formula CH₂O) in 40 g of water is observed to freeze at –0.465° C. The molecular formula of the compound is (K_f of water = 1.86 kg K mol^–1)

• a) C₆H₁₂O₆
• b) C₃H₆O₃
• c) C₂H₄O₂
• d) None of these

Answer:  C₆H₁₂O₆

Question: Blood cells retain their normal shape in solution which are

• a) isotonic to blood
• b) equinormal to blood
• c) hypotonic to blood
• d) hypertonic to blood

Answer: isotonic to blood

Question: Isotonic solutions have same

• a) molar concentration
• b) normality
• c) molality
• d) None of these

Answer: molar concentration

Question: As a result of osmosis, the volume of more concentrated solution

• a) gradually increases
• b) suddenly increases
• c) gradually decreases
• d) is not affected

Answer:  gradually increases

Question:  Which of the following pairs of solution are isotonic at the same temperature ?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Osmotic pressure of 0.4% urea solution is 1.64 atm and that of 3.42% cane sugar is 2.46 atm. When the above two solutions are mixed, the osmotic pressure of the resulting solution is

• a) 4.10 atm
• b) 2.46 atm
• c) 0.82 atm
• d) 1.64 atm

Answer: 4.10 atm

Question: Osmotic pressure of a solution at a given temperature

• a) increases with concentration
• b) decreases with concentration
• c) remains same
• d) initially increases and then decreases

Answer:  increases with concentration

Question: At 25°C, at 5 % aqueous solution of glucose (molecular weight = 180 g mol–1) is isotonic with a 2% aqueous solution containing an unknown solute. What is the molecular weight of the unknown solute?

• a) 72
• b) 60
• c) 80
• d) 63

Answer: 72

Question: Which one of the following statements is false?

• a) Two sucrose solutions of the same molality prepared in different solvents will have the same depression of freezing point
• b) Raoult’s law states that the vapour pressure of a component over a binary solution of volatile liquids is directly proportional to its mole fraction
• c) The correct order of osmotic pressures of 0.01 M solution of each compound is BaCl2 > KCl > CH3COOH > glucose
• d) None of these

Answer: Two sucrose solutions of the same molality prepared in different solvents will have the same depression of freezing point

Question: Which of the following statements is false?

• a) In reverse osmosis, solvent molecules move through a semipermeable membrane from a region of lower concentration of solute to a region of higher concentration
• b) The value of molal depression constant depends on nature of solvent
• c) Relative lowering of vapour pressure, is a dimensionless quantity
• d) Units of atmospheric pressure and osmotic pressure are the same

Answer: In reverse osmosis, solvent molecules move through a semipermeable membrane from a region of lower concentration of solute to a region of higher concentration

Question: During osmosis, flow of water through a semipermeable membrane is

• a) from solution having lower concentration only
• b) from both sides of semipermeable membrane with unequal flow rates
• c) from both sides of semipermeable membrane with equal flow rates
• d) from solution having higher concentration only

Answer: from solution having lower concentration only

Question: If 0.1 M solution of glucose and 0.1 M solution of urea are placed on two sides of the semipermeable membrane to equal heights, then it will be correct to say that

• a) there will be no net movement across the membrane
• b) glucose will flow towards urea solution
• c) urea will flow towards glucose solution
• d) water will flow from urea solution to glucose

Answer: there will be no net movement across the membrane

Question: The van’t Hoff factor i for a compound which undergoes dissociation in one solvent and association in other solvent is respectively

• a) greater than one and less than one
• b) greater than one and greater than one
• c) less than one and less than one.
• d) less than one and greater than one

Answer: greater than one and less than one

Question: If the various terms in the given below expressions have usual meanings, the van’t Hoff factor (i) cannot be calculated by which one of the following expressions

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Van’t Hoff factor is given by the expression ________.

• a) Both
• b)

  

• c)

  

• d) None of these

Answer: Both

Question: We have three aqueous solutions of NaCl labelled as 'A', 'B' and 'C' with concentrations 0.1M, 0.01M and 0.001M, respectively. The value of van't Hoff factor for these solutions will be in the order ________.

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer: