CBSE Class 12 Chemistry Solutions MCQs Set M

Question: Which of the following units is useful in relating concentration of solution with its vapour pressure?
a) Molality
b) Mole fraction
c) Parts per million
d) Mass percentage
Answer: b

Question: The term homogeneous mixtures signifies that
a) Its properties are uniform throughout the mixture
b) Neither composition nor properties are uniform throughout the mixture
c) Both composition and properties are uniform throughout the mixture
d) Its composition is uniform throughout the mixture
Answer: c

Question: Mixtures of ethanol and acetone show positive deviation. The reason is
a) In pure acetone, molecules are hydrogen bonded
b) In both, molecules are hydrogen bonded
c) In pure ethanol, molecules are hydrogen bonded
d) None of these
Answer: c

Question: Which of the following is a quantitative description of the solution?
a) Saturated
b) Concentrated
c) Dilute
d) Molar
Answer: d

Question: The statement illustrating Henry’s law is
a) Dalton’s law of partial pressure
b) Graham’s law
c) Raoult’s law
d) Henry’s law
Answer: d

Question: The decrease in the vapour pressure of solvent depends on the
a) Nature of non-volatile solute present in the solution
b) Quantity of non-volatile solute present in the solution
c) Physical state of non-volatile solute present in the solution
d) Molar mass of non-volatile solute present in the solution
Answer: b

Question: 2.5 litres of NaCl solution contain 5 moles of the solute. What is the molarity?
a) 12.5 molar
b) 2.5 molar
c) 2 molar
d) 5 molar
Answer: c

Question: Which one of the following is not correct for an ideal solution?
a) It must obey Raoult’s law
b) ΔH = 0
c) ΔH = ΔV ≠ 0
d) All are correct
Answer: c

Question: On adding a solute to a solvent having vapour pressure 0.80 atm, vapour pressure reduces to 0.60 atm. Mole fraction of solute is
a) 0.75
b) 0.33
c) 0.50
d) 0.25
Answer: d

Question: The vapour pressure of pure benzene at 25°C is 640 mm Hg and that of solution of solute A is 630 mm Hg. The molality of solution is
a) 0.5 m
b) 0.1 m
c) 0.2 m
d) 0.4 m
Answer: c

Question: Which of the following liquid pairs shows a positive deviation from Raoult’s law?
a) Water – Nitric acid
b) Acetone – Chloroform
c) Water – Hydrochloric acid
d) Benzene – Methanol
Answer: d

Question: 10 g of NaCl is dissolved in 106 g of the solution. Its concentration is
a) 1 ppm
b) 0.1 ppm
c) 100 ppm
d) 10 ppm
Answer: d

Question: 4.0 g of NaOH is dissolved in 100 ml solution. The normality of the solution is
a) 0.5 N
b) 1.0 N
c) 0.1 N
d) 4.0 N
Answer: b

Question: Mole fraction of the solute in a 1.00 molal aqueous solution is
a) 0.0344
b) 1.7700
c) 0.0177
d) 0.1770
Answer: c

Question: All form ideal solution except
a) C₆H₆ and C₆H₅CH₃
b) C₂H₆ and C₂H₅I
c) C₂H₅I and C₂H₅OH
d) C₆H₅Cl and C₆H₅Br
Answer: c

Question: 25 ml of a solution of barium hydroxide on titration with a 0.1 molar solution of hydrochloric acid gave a titre value of 35 ml. The molarity of barium hydroxide solution was
a) 0.14
b) 0.28
c) 0.07
d) 0.35
Answer: c

Question: The volume of 4 N HCl and 10 N HCl required to make 1 litre of 6 N HCl are
a) 0.80 litre of 4 N HCl and 0.20 litre of 10 N HCl
b) 0.50 litre of 4 N HCl and 0.50 litre of 10 N HCl
c) 0.75 litre of 10 N HCl and 0.25 litre of 4 N HCl
d) 0.67 litre of 4 N HCl and 0.33 litre of 10 N HCl
Answer: d

Question: Two liquids X and Y form an ideal solution. Vapour pressure data lead to pure vapour pressures (in mm Hg) of X and Y respectively as
a) 300 and 400
b) 400 and 600
c) 500 and 600
d) 200 and 300
Answer: b

Question: 200 ml of water is added to 500 ml of 0.2 M solution. What is the molarity of this diluted solution?
a) 0.7093 M
b) 0.2897 M
c) 0.1428 M
d) 0.5010 M
Answer: c

Question: For preparing 0.1 N solution of a compound from its impure sample of known percentage purity, the weight of substance required will be
a) Same as the theoretical weight
b) Less than the theoretical weight
c) None of these
d) More than the theoretical weight
Answer: d

Question: Which of the following concentration terms is/are independent of temperature?
a) Molarity and mole fraction
b) Molality only
c) Molality and mole fraction
d) Molality and normality
Answer: c

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) Pure water
b) Pure HCl
c) Pure water as well as pure HCl
d) Neither HCl nor H₂O in their pure states
Answer: d

Question: Value of Henry’s constant (Kₕ)
a) Decreases with increase in temperature
b) Remains constant
c) First increases then decreases
d) Increases with increase in temperature
Answer: d

Question: 5 ml of N HCl, 20 ml of N/2 H₂SO₄ and 30 ml of N/3 HNO₃ are mixed together and volume made to one litre. The normality of the resulting solution is
a) N/10
b) N/40
c) N/5
d) N/20
Answer: b

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) Zero
c) Greater than the rate of crystallisation
d) Equal to the rate of crystallisation
Answer: d

Question: A solution is prepared by dissolving 10 g NaOH in 1250 mL of a solvent of density 0.8 mL g⁻¹. The molality of the solution (mol kg⁻¹) is
a) 0.008
b) 0.0064
c) 0.25
d) 0.2
Answer: c

Question: On dissolving sugar in water at room temperature solution feels cool to touch. Under which of the following cases dissolution of sugar will be most rapid?
a) Sugar crystals in cold water
b) Powdered sugar in cold water
c) Sugar crystals in hot water
d) Powdered sugar in hot water
Answer: d

Question: According to Henry’s law, the amount of gas that will dissolve in blood plasma or any other liquid is determined by
a) The total pressure of the gas mixture
b) Solubility of the gas in the liquid
c) Osmotic pressure of the gas mixture
d) pH of the liquid
Answer: b

Question: Which of the following statements is incorrect?
a) An unsaturated solution is one in which more solute can be dissolved at the same temperature
b) The solution which is in dynamic equilibrium with undissolved solute is the saturated solution
c) A solution in which no more solute can be dissolved at the same temperature and pressure is called a saturated solution
d) The minimum amount of solute dissolved in a given amount of solvent is its solubility
Answer: d

Question: In a 0.2 molal aqueous solution of a weak acid HX, the degree of ionization is 0.3. (Kf for water = 1.85). The freezing point of the solution will be nearest to
a) –0.260°C
b) –0.481°C
c) +0.481°C
d) –0.360°C
Answer: b

Question: The vapour pressure of two liquids P and Q are 80 torr and 60 torr respectively. The total vapour pressure of solution obtained by mixing 3 moles of P and 2 moles of Q would be
a) 68 torr
b) 20 torr
c) 72 torr
d) 140 torr
Answer: c

Question: Henry’s law constant of oxygen is 1.4 × 10⁻³ mol L⁻¹ atm⁻¹ at 298 K. How much oxygen is dissolved in 100 mL at 298 K when the partial pressure of oxygen is 0.5 atm?
a) 22.4 mg
b) 3.2 g
c) 2.24 mg
d) 1.4 g
Answer: c

Question: When a solid solute is added to a solvent, some solute dissolves and its concentration increases in solution. This process is called _____. Some solute particles in solution collide with the solid solute particles and get separated out of solution. This process is called _____.
a) Crystallization, dissolution
b) Saturation, crystallization
c) Dissolution, crystallization
d) Dissolution, saturation
Answer: c

Question: Which of the following mixtures is/are called solution?
(i) Water + ammonia
(ii) Water + acetone
(iii) Acetone + alcohol
(iv) Hexane + water
a) (i), (ii) and (iii)
b) (ii) and (iii)
c) (i) and (iv)
d) (i), (iii) and (iv)
Answer: a

Question: A beaker contains a solution of substance A. Precipitation of substance A takes place when a small amount of A is added to the solution. The solution is
a) Saturated
b) Unsaturated
c) Concentrated
d) Supersaturated
Answer: d

Question: The vapour pressure of pure benzene and toluene at a particular temperature are 100 mm and 50 mm respectively. The mole fraction of benzene in vapour phase in contact with equimolar solution of benzene and toluene is
a) 0.75
b) 0.33
c) 0.67
d) 0.50
Answer: c

Question: What is the normality of a 1 M solution of H₃PO₄?
a) 2.0 N
b) 1.0 N
c) 0.5 N
d) 3.0 N
Answer: d

Question: Which of the following factor(s) affect the solubility of a gaseous solute in a fixed volume of liquid solvent?
(i) Nature of solute
(ii) Temperature
(iii) Pressure
a) (i) and (iii) at constant T
b) (ii) and (iii) only
c) (i) and (ii) at constant P
d) (iii) only
Answer: a

Question: People add sodium chloride to water while boiling eggs. This is to
a) Make eggs tasty
b) Prevent the breaking of eggs
c) Increase the boiling point
d) Decrease the boiling point
Answer: c

Question: The van’t Hoff factor (i) accounts for
a) Degree of solubilisation of solute
b) Extent of dissolution of solute
c) Extent of dissociation of solute
d) Degree of decomposition of solution
Answer: c