CBSE Class 12 Chemistry Solutions MCQs Set I

Question: A 1% solution of KCl (I), NaCl (II), BaCl₂ (III) and urea (IV) have their osmotic pressure at the same temperature in ascending order. Assume 100% ionisation of the electrolytes.
a) I < III < II < IV
b) III < I < II < IV
c) I < II < III < IV
d) I < III < IV < II
e) III < IV < I < II
Answer: e

Question: 29.2% (w/W) HCl stock solution has density of 1.25 g/mL. The molecular weight of HCl is 36.5 g/mol. The volume (mL) of stock solution required to prepare a 200 mL solution 0.4 M HCl is
a) 5.0 mL
b) 6.0 mL
c) 8.0 mL
d) 15.0 mL
Answer: c

Question: Dissolving 120 g of urea (mol. wt. 60) in 1000 g of water gave a solution of density 1.15 g/mL. The molarity of the solution is
a) 1.78 M
b) 2.00 M
c) 2.05 M
d) 2.22 M
Answer: c

Question: At STP, a container has l mole of Ar, 2 moles of CO₂ , 3 moles of O₂ and 4 moles of N₂ . Without changing the total pressure if one mole of O₂ is removed, the partial pressure of O₂ is
a) changed by about 16%
b) halved
c) changed by 26%
d) unchanged
Answer: c

Question: 138 gofethyl alcohol is mixed with 72 gofwater. The ratio of mole fraction of alcohol to water is 
a) 3 : 4
b) 1 : 2
c) 1 : 4
d) 1 : 1
Answer: a

Question: An aqueous solution of glucose is 20% in strength. The volume in which 1 g-mole of it is dissolved will be
a) 9 L
b) 1.8 L 
c) 8 L
d) 0.9 L
Answer: d

Question: Two solutions of HCl, A and B have concentrations of 0.5 N and 0.1 M respectively. The volume of solutions A and B required to make 2 L of 0.2 N HCl are
a) 0.5 L of A + 1.5 L of B
b) 1.5 L of A + 0.5 L of B
c) 1.0 L of A + 1.0 L of B
d) 0.75 L of A + 1.25 L of B
Answer: a

Question: The density of a 3M sodium thiosulphate (Na₂S₂O₃) solution is 1.25 g/mL. Calculate the percent by weight of sodium thiosulphate
a) 12.65%
b) 37.92%
c) 0.87%
d) 63.21%
Answer: b

Question: Isotonic solutions have equal
a) Vapour pressure
b) Osmotic pressure
c) Boiling point
d) Freezing point
Answer: b

Question: 25 cm³ of oxalic acid completely neutralise 0.064 g of sodium hydroxide. Molarity of the oxalic acid solution is
a) 0.064
b) 0.045
c) 0.015
d) 0.032
Answer: d

Question: Calculate the normality of 250 mL aqueous solution of H₂SO₄ having pH = 0.00
a) 0.25 N
b) 0.50 N
c) 1 N
d) 2 N
Answer: b

Question: Molar solution means 1 mole of solute present in 
a) 1000 g of solvent
b) 1 L of solvent 
c) 1 L of solution
d) 1000 g of solution
Answer: c

Question: Find the boiling point of a solution of 5.00 g ofnapthalene (C₁₀H₈ ) in 100 g of benzene. Kb of benzene if 2.53° elm the nom1al boiling point of benzene = 80° C 
a) 81°C
b) 85°C
c) 0.9°C
d) 79°C
Answer: a

Question: An aqueous solution of phosphoric acid, H₃PO₄ being titrated has molarity equal to 0.25 M. Which of the following could be normality of this solution?
a) 0.25 N
b) 0.50 N
c) 0.75 N
d) All of the options
Answer: d

Question: 50 cm³ of 0.2 N HCl is titrated against 0.1 N NaOH solution. The titration is discontinued after adding 50 cm³ of NaOH. The remaining titration is completed by adding 0.5 N KOH. The volume of KOH required for completing the titration is
a) 12 cm³
b) 10 cm³
c) 25 cm³
d) 10.5 cm³
Answer: b

Question: How many grams of sulphuric acid is to be dissolved to prepare 200 mL aqueous solution having concentration of [H₃O⁺] ions 1 M at 25°C ([H=1, O=16, S=32 g/mol])
a) 4.9 g
b) 19.6 g
c) 9.8 g
d) 0.98 g
Answer: c

Question: Molality of 2.5 g of ethanoic acid (CH₃COOH) in 75 g of benzene is
a) 0.565 mol/kg
b) 0.656 mol/kg
c) 0.556 mol/kg
d) 0.665 mol/kg
Answer: c

Question: Which of the following will represent the normality of 10% (w/V) acetic acid?
a) 1.66 N
b) 16.6 N
c) 3.32 N
d) 33.2 N
Answer: a

Question: 2 N HCl solution will have same molar concentration as
a) 4.0 N H₂SO₄
b) 0.5 N H₂SO₄
c) 1 N H₂SO₄
d) 2 N H₂SO₄
Answer: a

Question: Vapour pressure of pure A = 100 torr, moles = 2; vapour pressure of pure B = 80 torr, moles = 3. Total vapour pressure of the mixture is
a) 440 torr
b) 460 torr
c) 180 torr
d) 88 torr
Answer: d

Question: How many grams of NaOH will be required to prepare 500 g solution containing 10% w/w NaOH solution?
a) 100 g
b) 50 g
c) 0.5 g
d) 5.0 g
Answer: b

Question: 40% by weight solution will contain how much mass of the solute in 1L solution, density of the solution is 1.2 g/mL?
a) 480 g
b) 48 g 
c) 38 g
d) 380 g
Answer: a

Question: To neutralise completely 20 mL of0.1 M aqueous solution of phosphorous acid (H₃PO₃) the volume of 0.1 M aqueous KOH solution required is
a) 10 mL
b) 20 mL
c) 40 mL
d) 60 mL
Answer: c

Question: How many moles of Al₂ (SO₄)₃ would be in 50 g of the substance ?
a) 0.083 mol
c) 0.481 mol
b) 0.952 mol
d) 0.140 mol
Answer: d

Question: Density of a 2.05 M solution of acetic acid in water is 1.02 g/mL. The molality of the solution is 
a) 1.14 mol kg^-1
b) 3.28 mol kg^-1
c) 2.28 mol kg^-1
d) 0.44 mol kg^-1
Answer: c

Question: A 5.2 molal aqueous solution of methyl alcohol, CH₃OH, is supplied. What is the mole fraction of methyl alcohol in the solution?
a) 1.100
b) 0.190
c) 0.086
d) 0.050
Answer: c

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

Question: Two liquids X and Y form an ideal solution. The mixture has a vapour pressure of 400 mm at 300 K when mixed in the molar ratio of 1:1 and a vapour pressure of 350 mm when mixed in the molar ratio of 1:2. The vapour pressures of the two pure liquids X and Y respectively are
a) 250 mm, 550 mm
b) 350 mm, 450 mm
c) 350 mm, 700 mm
d) 500 mm, 500 mm
e) 550 mm, 250 mm
Answer: e

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

Question: Which of the following concentration factors is affected by change in temperature?
a) Molarity
b) Molality
c) Mole fraction
d) Weight fraction
Answer: a

Question: Out of following which one is not an example of a solution?
a) Air
b) Brass
c) Amalgam
d) Benzene in water
Answer: d

Question: The Henry’s law constant for the solubility of N₂ gas in water at 298 K is 1.0 x 10⁵ atm. The mole fraction of N₂ in air is 0.8. The number of moles of N₂ from air dissolved in 10 moles of water at 298 K and 5 atm pressure is
a) 4 x 10^-4
b) 4.0 x 10^-5
c) 5.0 x 10^-4
d) 4.0 x 10^-6
Answer: a

Question: 10 cm³ of 0.1 N monobasic acid requires 15 cm³ of sodium hydroxide solution whose normality is
a) 1.5 N
b) 0.15 N
c) 0.066 N
d) 0.66 N
Answer: c

Question: The molar mass of a solute X in g mol^-1 ,if its 1 % solution is isotonic with a 5% solution of cane sugar (molar mass = 342g mol^-1) is 
a) 68.4
b) 34.2
c) 136.2
d) 171.2
Answer: a

Question: The volume of water to be added to N / 2 HCl to prepare 500cm³ of N / 10 solution is
a) 450 cm³
b) 100 cm³
c) 45 cm³
d) 400 cm³
Answer: d

Question: The molarity of a given orthophosphoric acid solution is 3 M. Its normality is
a) 9 N
b) 0.3 N
c) 3 N
d) 1 N
Answer: a

Question: What is the molality of a urea solution in which 0.0100 g of urea, [(NH₂)₂CO], is added to 0.3000 dm³ of water at STP?
a) 0.555 m
b) 5.55 x 10^-4 m
c) 33.3 m
d) 3.33 x 10^-2 m
Answer: b

Question: Two bottles A and B contain 1 M and 1 m aqueous solution of sulphuric acid respectively
a) A is more concentrated than B
b) B is more concentrated than A
c) Concentration of A is equal to concentration of B
d) It is not possible to compare the concentrations
Answer: a

Question: A 5 molar solution of H₂SO₄ is diluted from 1 L to 10 L. What is the normality of the solution? 
a) 0.25N
b) 1 N
c) 2 N
d) 7 N
Answer: b

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

Question: A solution is prepared by dissolving 24.5 g of sodium hydroxide in distilled water to give IL solution. The molarity of NaOH in the solution is 
(Given, that molar mass of NaOH = 40.0g mol^{– 1})
a) 0.2450 M
b) 0.6125 M
c) 0.9800 M
d) 1.6326 M
Answer: d

Question: 25 mL of a solution of 0.4 M HCl and 0.9 M HCl are to be mixed such that the concentration of the resultant solution becomes 0.7 M. The ratio of volumes should be
a) 4:9
b) 2:3
c) 3:2
d) 1:1
Answer: b

Question: What is the total number of moles of H₂SO₄ needed to prepare 5.0 L of a 2.0 M solution of H₂SO₄?
a) 2.5
b) 5.0
c) 10
d) 20
Answer: c

Question: Consider separate solution of 0.500 M C₂H₅OH(aq), 0.100 M Mg³ (PO₄ )₂ (aq), 0.250 M KBr (aq)and0.125 M Na₃PO₄ (aq)i at 25° C. Which statement is true about these solution assuming all salts to be strong electrolytes. 
a) They all have same osmotic pressure 
b) 0.100 M Mg₃ (PO₄ )₂ (aq) has the highest osmotic pressure
c) 0.125 M Na₃ PO₄ (aq) has the highest osmotic pressure
d) 0.500 M C₂H₅OH(aq) has the highest osmotic pressure
Answer: a

Question: If the elevation in boiling point of a solution of 10 g of solute (mol. wt= 100) in 100 g of water is ΔT_b, the ebullioscopic constant of water is 
a) 10
b) 100T_b
c) ΔT_b
d) ΔT_b/10
Answer: c

Question: The molality of pure water is
a) 1
b) 18
c) 55.5
d) None of the options
Answer: c

Question: The volume of 0.1 M oxalic acid that can be completely oxidised by 20 mL of 0.025 M KMnO₄ solution is
a) 25 mL
b) 12.5 mL
c) 37.5 mL
d) 125 mL
Answer: 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) 2/3
b) 1/3 x 273/298
c) 1/3
d) 1/2
Answer: c

Question: Which of the following will show a negative deviation from Raoult’s law? 
a) Acetone-benzene
b) Acetone-ethanol
c) Benzene-methanol
d) Acetone-chloroform
Answer: d

Question: A solution of two liquids boils at a temperature more than the boiling point of either them. Hence, the binary solution shows
a) negative deviation from Raoult’s law
b) positive deviation from Raoult’s law
c) no deviation from Raoult’s law
d) positive or negative deviation from Raoult’s law depending upon the composition
Answer: a