CBSE Class 12 Chemistry Solutions MCQs Set B

Question. Dilute one litre 1 molar H₂SO₄ solution by 5 litre water, the normality of that solution is:
a. 0.2 N
b. 5 N
c. 10 N
d. 0.33 N
Answer : D

Question. Which of the following should be done in order to prepare 0.40M NaCl starting with 100ml of 0.30M NaCl (mol.wt. of NaCl = 58.5)?
a. Add 0.585 g NaCl
b. Add 20 ml water
c. Add 0.010 ml NaCl
d. Evaporate 10 ml water
Answer : A

Question. Which of the following is not a colligative property?
a. Osmotic pressure
b. Elevation in B.P.
c. Vapour pressure
d. Depression in freezing point
Answer : C

Question. 9.8g of H₂SO₄ is present in 2 litres of a solution. The molarity of the solution is:
a. 0.1 M
b. 0.05 M
c. 0.2 M
d. 0.01 M
Answer : B

Question. If two substances A and B have P⁰_A : P⁰_B =1: 2 and have mole fraction in solution 1 : 2 then mole fraction of A in vapours:
a. 0.33
b. 0.25
c. 0.52
d. 0.2
Answer : D

Question. Which solution will show the maximum vapour pressure at 300 K ?
a. 1 M C₁₂ H₂₂ O₁₁
b. 1 M CH₃ COOH
c. 1 M NaCl₃
d. 1 M NaCl
Answer : A

Question. How many grams of CH₃ OH should be added to water to prepare 150ml solution of  2MCH₃OH?
a. 9.6
b. 2.4
c. 9..6×10³
d. 2.4×10³
Answer : A

Question. The molarity of 0.006 mole of NaCl in 100 ml solution is:
a. 0.6
b. 0.06
c. 0.006
d. 0.066
Answer : B

Question. A 5% solution of canesugar (mol. wt. = 342) is isotonic with 1% solution of a substance X. The molecular weight of X is:
a. 34.2
b. 171.2
c. 68.4
d. 136.8
Answer : C

Question. A non ideal solution was prepared by mixing 30 ml chloroform and 50 ml acetone. The volume of mixture will be:
a. > 80 ml
b. < 80 ml
c. = 80 ml
d. ≥ 80 ml
Answer : B

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

Question. A liquid mixture boils without changing constituent is called:
a. Stable structure complex
b. Binary liquid mixture
c. Zeotropic liquid mixture
d. Azeotropic liquid mixture
Answer : D

Question. Which one of the following mixtures can be separated into pure components by fractional distillation?
a. Benzene–toluene
b. Water–ethyl alcohol
c. Water–nitric acid
d. Water–hydrochloric acid
Answer : A

Question. Which of the following colligative properties can provide molar mass of proteins (or polymers or colloids) with greater precision?
a. Relative lowering of vapour pressure
b. Elevation of boiling point
c. Depression in freezing point
d. Osmotic pressure
Answer : D

Question. What volume of 0.8 M solution contains 0.1 mole of the solute?
a. 100 ml
b. 125 ml
c. 500 ml
d. 62.5
Answer : B

Question. Which of the following is a colligative property?
a. Osmotic pressure
b. Boiling point
c. Vapour pressure
d. Freezing point
Answer : A

Question. Which of the following 0.10m aqueous solution will have the lowest freezing point?
a. Al₂ (SO₄)₃
b. C₃ H₁₀ O₅
c. KI
d. C₁₂ H₂₂ O₁₁
Answer : A

Question. Which of the following will have the lowest vapour pressure?
a. 0.1 M KCl solution
b. 0.1 M urea solution
c. 0.1MNa₂ SO₄ solution
d. 0.1MK₄ Fe(CN)₆ solution
Answer : D

Question. If 5.85 gms of NaCl are dissolved in 90 gms of water, the mole fraction of NaCl is:
a. 0.1
b. 0.2
c. 0.3
d. 0.0196
Answer : D

Question. Two solutions A and B are separated by semi- permeable membrane. If liquid flows from A to B then:
a. A is less concentrated than B
b. A is more concentrated than B
c. Both have same concentration
d. None of these
Answer : A

Question. A solution of Al₂ (SO₄)₃ {d = 1.253gm/ml} contain 22% salt by weight. The molarity, normality and molality of the solution is:
a. 0.805 M, 4.83 N, 0.825 M
b. 0.825 M, 48.3 N, 0.805 M
c. 4.83 M, 4.83 N, 4.83 M
d. None
Answer : A

Question. The molality of 90% H₂ SO₄ solution is: [density=1.8 gm/ml]
a. 1.8
b. 48.4
c. 9.18
d. 94.6
Answer : C

Question. The elevation in boiling point of a solution of 13.44g of CuCl₂ in 1kg of water using the following information will be: (Molecular weight of CuCl₂=134.4 and K_b=0.52K molal⁻¹)
a. 0.16
b. 0.05
c. 0.1
d. 0.2
Answer : A

Question. The average osmotic pressure of human blood is 7.8 bar at 37°C. What is the concentration of an aqueous NaCl solution that could be used in the blood stream?
a. 0.16 mol/L
b. 0.32 mol/L
c. 0.60 mol/L
d. 0.45 mol/L
Answer : B

Question. A solution of urea (mol. mass 56g mol^–1) boils at 100.18°C at the atmospheric pressure. If K_f and K_b for water are1.86 and 0.512K kg mol^–1 respectively the above solution will freeze at:
a. – 6.54°C
b. 6.54°C
c. 0.654°C
d. 0.654°C
Answer : D

Question. 3.65 gms of HCl is dissolved in 16.2 gms of water. The mole fraction of HCl in the resulting solution is:
a. 0.4
b. 0.3
c. 0.2
d. 0.1
Answer : D

Question. On dissolving 1 mole of each of the following acids in 1 litre water, the acid which does not give a solution of strength 1 N is?
a. HCl
b. Perchloric acid
c. HNO₃
d. Phosphoric acid
Answer : D

Question. The number of moles of KCl in 1000 ml of 3 molar solutions is:
a. 1
b. 2
c. 3
d. 1.5
Answer : C

Question. A solution contains 1 mole of water and 4 mole of ethanol. The mole fraction of water and ethanol will be:
a. 0.2 water + 0.8 ethanol
b. 0.4 water + 0.6 ethanol
c. 0.6 water + 0.8 ethanol
d. 0.8 water + 0.2 ethanol
Answer : A

Question. 171 g of cane sugar (C₁₂ H₂₂ O₁₁) is dissolved in 1 litre of water. The molarity of the solution is:
a. 2.0 M
b. 1.0 M
c. 0.5 M
d. 0.25 M
Answer : C

Question. A mixture has 18g water and 414g ethanol. The mole fraction of water in mixture is: (assume ideal behaviour of the mixture)
a. 0.1
b. 0.4
c. 0.7
d. 0.9
Answer : A

Question. If 1 M and 2.5 litre NaOH solution is mixed with another 0.5 M and 3 litre NaOH solution, then molarity of the resultant solution will be:
a. 1.0 M
b. 0.73 M
c. 0.80 M
d. 0.50 M
Answer : B

Question. The amount of K₂ Cr₂ O₇ (eq.wt.49.04) required to prepare 100 ml of its 0.05 N solution is:
a. 2.9424 g
b. 0.4904 g
c. 1.4712 g
d. 0.2452 g
Answer : D

Question. In a mixture of 1 gm H₂ and 8gm O₂ , the mole fraction of hydrogen is:
a. 0.667
b. 0.5
c. 0.33
d. None of these
Answer : A

Question. Vapour pressure of CCl₄ at o 25 C is 143mm of Hg 0.5gm of a non-volatile solute (mol. wt.=65) is dissolved in 100mlCCl₄ . Find the vapour pressure of the solution:
(Density of CCl₄ = 1.58g / cm²)
a. 141.43mm
b. 94.39mm
c. 199.34mm
d. 143.99mm
Answer : A

Question. A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressure of the pure hydrocarbons at 20°C are 440 mmHg for pentane and 120 mmHg for hexane. The mole fraction of pentane in the vapour phase would be:
a. 0.549
b. 0.200
c. 0.786
d. 0.478
Answer : D

Question. A dry air is passed through the solution, containing the 10 gm of solute and 90 gm of water and then it pass through pure water. There is the depression in weight of solution wt by 2.5 gm and in weight of pure solvent by 0.05 gm.
Calculate the molecular weight of solute:
a. 50
b. 180
c. 100
d. 25
Answer : C

Question. Elevation in boiling point was o 0.52 C when 6gm of a compound X was dissolved in 100gm of water. Molecular weight of X is: b (K for water is 0.52 per 1000 gm of water)
a. 120
b. 60
c. 180
d. 600
Answer : B

Question. The vapour pressure of pure liquid A is 0.80 atm. On mixing a non-volatile B to A, its vapour pressure becomes 0.6 atm. The mole fraction of B in the solution is:
a. 0.150
b. 0.25
c. 0.50
d. 0.75
Answer : B

Question. The vapour pressure of benzene at a certain temperature is 640 mm of Hg. A non-volatile and non-electrolyte solid weighing 2.175 g is added to 39.08 g of benzene. The vapour pressure of the solution is 600 mm of Hg. What is the molecular weight of solid substance?
a. 49.50
b. 59.6
c. 69.5
d. 79.8
Answer : C

Question. When 10g of a non-volatile solute is dissolved in 100 g of benzene, it raises boiling point by o 1 C then molecular mass of the solute is: b (K_b for benzene = 2.53k-m^–1)
a. 223 g
b. 233 g
c. 243 g
d. 253 g
Answer : D

Question. The amount of urea to be dissolved in 500 ml of water (K =18.6K mole⁻¹ in 100g solvent) to produce a depression of o 0.186 C in freezing point is:
a. 9 g
b. 6 g
c. 3 g
d. 0.3 g
Answer : C

Question. The freezing point of a 0.01M aqueous glucose solution at 1 atmosphere is o −0.18 C. To it, an addition of equal volume of 0.002M glucose solution will; produce a solution with freezing point of nearly:
a. −0.036^o C
b. −0.108^o C
c. −0.216^o C
d. −0.422^o C
Answer : C

Question. For 0.1 M solution, the colligative property will follow the order:
a. NaCl > Na₂ SO₄ > Na₃ PO₄
b. NaCl < Na₂ SO₄ < Na₃ PO₄
c. NaCl > Na₂ SO₄ ≈ Na₃ PO₄
d. NaCl < Na₂ SO₄ = Na₃ PO₄
Answer : B

Question. The ratio of the value of any colligative property for KCl solution to that for sugar solution is nearly:
a. 1
b. 0.5
c. 2.0
d. 3
Answer : C

Question. Calculate the molal depression constant of a solvent which has freezing point 16.6^o C and latent heat of fusion 180.75 Jg⁻¹
a. 2.68
b. 3.86
c. 4.68
d. 2.86t6
Answer : B

Question. In equimolar solution of glucose, NaCl and BaCl2, the order of osmotic pressure is as follow:
a. Glucose  >NaCl > BaCl₂
b.  NaCl > BaCl₂ > Glucose
c.  BaCl₂ > NaCl > Glucose
d. Glucose > BaCl₂ > NaCl
Answer : C

Question. Which one of the following aqueous solutions will exhibit highest boiling point?
a. 0.015 M urea
b. 0.01MKNO₃
c. 0.01MNa₂ SO₄
d. 0.015M glucose
Answer : C

Question. Which of the following compounds corresponds Van't Hoff factor ' i' to be equal to 2 for dilute solution?
a. K₂SO₄
b. 4 NaHSO₄
c. Sugar
d. MgSO₄
Answer : D

Question. Acetic acid dissolved in benzene shows a molecular weight of:
a. 60
b. 120
c. 180
d. 240
Answer : B

Solutions

I. MCQ - Choose Appropriate Alternative

1. Molarity is the number of moles of a solute dissolved per __________. (dm³ of a solution, dm³ of solvent, Kg of solvent)

2. Molality is defined as the number of moles of solute dissolved per __________. (dm³ of solution, kg of solvent, kg of solute)

3. The solubility of a solute __________ with the increase of temperature. (increases, decreases, does not alter)

4. The loss of electron during a chemical reaction is known as __________. (Oxidation, Reduction, Neutralization)

5. The gain of electron during a chemical reaction is known as __________. (Oxidation, Reduction, Neutralization)

6. The ions, which are attracted towards the anode, are known as __________. (Anins, Cations, Positron).

7. The pH of a neutral solution is __________. (1.7, 7, 14)

8. A current of one ampere flowing for one minute is equal to __________. (One coulomb, 60 coulomb, one Faraday)

9. A substance, which does not allow electricity to pass through, is known as __________. (Insulator, Conductor, Electrolyte)

10. Such substances, which allow electricity to pass through them and are chemically decomposed, are called __________. (Electrolytes, Insulators, Metallic conductors)

11. __________ is an example of strong acid. (Acetic Acid, Carbonic Acid, Hydrochloric Acid)

12. __________ is an example of weak acid. (Hydrochloric Acid, Acetic Acid, Sulphuric Acid)

13. When NH4Cl is hydrolyzed, the solution will be __________. (Acidic, Basic, Neutral)

14. When Na2CO3 is hydrolyzed, the solution will be __________. (Acidic, Basic, Neutral)

15. When blue hydrated copper sulphate is heated __________. (It changes into white, it turns black, it remains blue)

16. Sulphur has the highest oxidation number in __________. (SO₂, H₂SO₄, H₂SO₃)

17. The reaction between an acid and a base to form a salt and water is called __________. (Hydration, Hydrolysis, Neutralization)

18. __________ is opposite of Neutralization. (Hydration, Hydrolysis, Ionization)

19. The substance having pH value 7 is __________. (Basic, Acidic, Neutral)

20. An aqueous solution whose pH is zero is __________. (Alkaline, Neutral, Strongly Acidic)

21. Solubility product of slightly soluble salt is denoted by __________. (Kc, Kp, Ks_p)

22. The increase of oxidation number is known as __________. (Oxidation, Reduction, Hydrolysis)

23. The decrease of Oxidation number is known as __________. (Oxidation, Reduction, Electrolysis)

24. One molar solution of glucose contains __________ gms of glucose per dm3 of solution. (180, 100, 342)

25. The number of moles of solute present per dm3 of solution is called __________. (Molality, Molarity, Normality)

26. ‘M’ is the symbol used for representing __________.(Molality, Molarity, Normality)

27. 1 mole of H2SO4 is equal to __________.(98gms, 49gms, 180gms)

28. Buffer solution tends to __________ pH.

29. The logarithm of reciprocal of hydroxide ion is represented as __________.(pH, pOH, pOH)

30. In __________ water molecules surround solute particles.(Hydration, Hydrolysis, Neutralization)