Chapter-2 Solutions MCQs
Q 81.: The mole fraction of water in a sulphuric acid solution is 0.85. The molality of the solution is :
(A) 4.9 mol/Kg
(B) 8.6 mol/Kg
(C) 9.2 mol/Kg
(D) 9.8 mol/Kg
Option – D
Q 82.: The vapour pressure of a solution of benzene and toluene is (mole fraction of benzene is 0.2, vapour pressure of pure benzene and pure toluene are 160 mmHg and 60 mmHg respectively)
(A) 48 mmHg
(B) 42 mmHg
(C) 37 mmHg
(D) 35 mmHg
Option – A
Q 83.: Which of the following solution pair can be separated into its pure components by fractional distillation ?
(A) Water and Ethyl alcohol
(B) Water and Hydrochloric acid
(C) n-Hexane and n-Heptane
(D) Acetone and Chloroform
Option – C
Q 84.: Which of the following statements about the ideal solution is incorrect ?
(A) Enthalpy of mixing = 0
(B) Free energy change of mixing = 0
(C) Volume of mixing = 0
(D) Obeys Raoult’s law
Option – B
Q 85.: Two liquids ‘A’ and ‘B’ have vapour pressure of 0.685 bar and 0.264 bar respectively. In an ideal solution of the two, the mole fraction of ‘A’ at which the two liquids have equal partial pressure is :
(A) 0.306
(B) 0.714
(C) 0.286
(D) 0.386
Option – C
Q 86.: The molal elevation constant is the ratio of elevation in boiling point to :
(A) Molarity
(B) Molality
(C) Boiling point of pure solvent
(D) Mole fraction
Option – B
Q 87.: The amount of solute (molar mass = 60 gm/mol) that must be added to 180 gm of water so that the vapour pressure of water is lowered by 10 % is :
(A) 20 gm
(B) 30 gm
(C) 40 gm
(D) 60 gm
Option – D
Q 88.: A solution containing 62 gm of ethylene glycol (molar mass 62 gm/mol) in 250 gm water is cooled to −10 °C. If Kf for water is 1.86 K Kg mol−1, the amount of water separated as ice is :
(A) 64 gm
(B) 48 gm
(C) 32 gm
(D) 16 gm
Option – A
Q 89.: On dissolving 3.24 gm of sulphur in 40 gm of benzene, boiling point of solution was higher than that of benzene by 0.81 K. The molecular formula of sulphur is (Given that Kb for benzene is 2.56 K Kg mol−1):
(A) S2
(B S4
(C) S6
(D) S8
Option – D
Q 90.: What happens when blood cells are placed in pure water ?
(A) The fluid in blood cells rapidly moves into water
(B) The water molecules rapidly move into blood cells
(C) The blood cells dissolve in water
(D) The blood cell first shrink and then swell up.
Option – B
Q 91.: An aqueous solution boils at 100.512 °C. The freezing point of the solution is (Kf = 1.86 K Kg mol−1 and Kb = 0.512 K Kg mol−1) :
(A) 0.93 °C
(B) −0.93 °C
(C) 1.86 °C
(D) −1.86 °C
Option – D
Q 92.: Solution ‘A’ contains 1 gm of urea in 100 mL of solution and solution ‘B’ contains 2 gm of glucose in 100 mL of solution. Point out the correct statement :
(A) Boiling point of ‘A’ will be less than ‘B’
(B) Freezing point of ‘A’ will be less than ‘B’
(C) Osmotic pressure of ‘A’ will be less than ‘B’
(D) Both will have same boiling point, freezing point and osmotic pressure.
Option – B
Q 93.: 1 mole of a liquid ‘A’ and 2 mole of liquid ‘B’ form a solution having a total vapour pressure of 46 torr. The vapour pressure of pure liquids ‘A’ and ‘B’ are 36 and 48 torr respectively. The solution :
(A) is an ideal solution
(B) shows negative deviation from Raoult’s law
(C) shows positive deviation from Raoult’s law
(D) dissolution is exothermic
Option – C
Q 94.: Two liquids ‘A’ and ‘B’ form ideal solutions having vapour pressure 200 and 100 mmHg respectively. The mole fraction of ‘A’ in vapour phase in equilibrium with an equimolar solution of the two is :
(A) 0.33
(B) 0.61
(C) 0.46
(D) 0.67
Option – D
Q 95.: What will be the relation between osmotic pressure at 273 K if 12 gm of urea, 12 gm of glucose and 12 gm of sucrose have osmotic pressures P1, P2 and P3 respectively when dissolved in the same amount of water ?
(A) P3 > P2 > P1
(B) P1 > P2 > P3
(C) P2 > P1 > P3
(D) P3 > P1 > P2
Option – B