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UNIT 01: SOLUTION PREVIOUS YEAR QESTIONS CBSE BOARD
Mass Percentage, Mole Fraction, Molarity, Molality
MCQ
1. Assertion (A): Molality of a solution in liquid state changes with temperature.
Reason (R): The volume of solution changes with the change in temperature.
(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is correct, but Reason (R) is incorrect statement.
(d) Assertion (A) is incorrect, but Reason (R) is correct statement. (2020)
2. 50 mL of an aqueous solution of glucose C6H12O6 (Molar mass: 180 g/mol) contains 6.02 x 1022 molecules. The concentration of the solution will be
(a) 0.1 M
(b) 0.2 M
(c) 1.0 M
(d) 2.0 M (2020)
VSA (1 mark)
3. Define the following term: Molality (m) (NCERT, 1/2, Delhi 2017)
4. Define the following term: Molarity (M) (NCERT, 1/2, Delhi 2017)
Solubility of Gas in a Liquid (Henry's Law)
MCQ
5. The value of Henry's constant KH is
(a) greater for gases with higher solubility
(b) greater for gases with lower solubility
(c) constant for all gases
(d) not related to the solubility of gases. (2025)
6. Value of Henry's constant KH
(a) increases with decrease in temperature
(b) decreases with increase in temperature
(c) increases with increase in temperature
(d) remains constant. (2023)
7. On dissolving ammonium chloride in water at room temperature, the solution feels cool to touch. Under which of the following conditions does salt dissolve faster?
(a) Powdered salt in cold water
(b) Powdered salt in hot water
(c) Salt crystals in cold water
(d) Salt crystals in hot water (2023)
8. Low concentration of oxygen in the blood and tissues of people living at high altitude is due to
(a) high atmospheric pressure
(b) low temperature
(c) low atmospheric pressure
(d) both low temperature and high atmospheric pressure. (2023)
9. An unknown gas 'X' is dissolved in water at 2.5 bar pressure and has mole fraction 0.04 in solution. The mole fraction of 'X' gas when the pressure of gas is doubled at the same temperature is
(a) 0.08
(b) 0.04
(c) 0.02
(d) 0.92 (Term I, 2021-22)
VSA (1 mark)
10. Why aquatic animals are more comfortable in cold water than in warm water? (1/3, 2018)
11. Gas (A) is more soluble in water than gas (B) at the same temperature. Which one of the two gases will have the higher value of K₁ (Henry's constant) and why? (1/2, 2016)
SAI (2 marks)
12. State Henry's law. Why are aquatic species more comfortable in cold water as compared to warm water? (2025)
13. What is Henry's law? Give one application of it. (2023)
14. State Henry's law and mention two of its important applications. (2020)
15. State Henry's law. Why is air diluted with helium in the tanks used by scuba divers? (2/5, 2020)
16. State Henry's law. Calculate the solubility of CO2 in water at 298 K under 760 mm Hg.
(KH for CO2 in water at 298 K is 1.25 x 106 mm Hg) (2020)
17. Give reasons for the following.
(a) Aquatic species are more comfortable in cold water than in warm water.
(b) At higher altitudes people suffer from anoxia resulting in inability to think. (Al 2019)
SA II (3 marks)
18. Henry's law constant for CO2 in water is 1.67 × 108 Pa at 298 K. Calculate the number of moles of CO₂ in 500 mL of soda water when packed under 2.53 x 105 Pa at the same temperature. (2025)
1.4 Vapour Pressure of Liquid Solutions
Raoult's Law
MCQ
19. Which of the following formula represents Raoult's law for a solution containing non-volatile solute?
(a) psolute = . Xsolute
(b) p= KH. X
(c) ptotal = psolvent
(d) psolute = . Xsolvent (Term I, 2021-22)
VSA (1 mark)
20. Identify which liquid will have a higher vapour pressure at 90 °C if the boiling points of two liquids A and B are 140 °C and 180 °C, respectively. (One word, 2020)
SAI (2 marks)
21. State Raoult's law for a solution containing volatile components. Why is the vapour pressure of an aqueous solution of glucose lower than that of water?(2025)
22. State Raoult's law for a solution containing volatile components. What is the similarity between Raoult's law and Henry's law? (2020)
Ideal and Non-ideal Solutions
MCQ
23. A solution of acetone in chloroform
(a) obeys Raoult's law
(b) forms azeotrope
(c) shows a positive deviation from Raoult's law
(d) shows a negative deviation from Raoult's law. (2025)
24. A solution of acetone in ethanol
(a) obeys Raoult's law
(b) forms an ideal solution
(c) shows a positive deviation from Raoult's law
(d) shows a negative deviation from Raoult's law.(2025)
25. An azeotropic solution of two liquids has a boiling point lower than either of the two when it
(a) shows a positive deviation from Raoult's law
(b) shows a negative deviation from Raoult's law
(c) shows no deviation from Raoult's law
(d) is saturated. (2024, Term I, 2021-22)
26. Which one of the following pairs will form an ideal solution?
(a) Chloroform and acetone
(b) Ethanol and acetone
(c) n-Hexane and n-heptane
(d) Phenol and aniline (Term 1, 2021-22)
27. On mixing 20 mL of acetone with 30 mL of chloroform, the total volume of the solution is
(a) < 50 mL
(b) = 50 mL
(c) > 50 mL
(d) = 10 mL (Term I, 2021-22)
VSA(1 mark)
28. What happens when acetone is added to pure ethanol? (1/2, 2020)
29. Define the following term: Ideal solution. (1/2, Delhi 2017, 1/5, Al 2017 C)
30. In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes? (1/2, Al 2016)
SAI (2 marks)
31. Give reasons:
(a) Cooking is faster in pressure cooker than in an open pan.
(b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution? What change in temperature would you observe after mixing liquids X and Y? (2025)
32. Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law? Give an example. (2025)
33. The vapour pressure of pure liquid X and pure liquid Y at 25 °C are 120 mm Hg and 160 mm Hg respectively. If equal moles of X and Y are mixed to form an ideal solution, calculate the vapour pressure of the solution. (2023)
34. What type of deviation from Raoult's law is observed by mixing chloroform and acetone? Why is a decrease in a vapour pressure observed in mixing chloroform and acetone? (2021)
35. Write two differences between ideal solutions and non-ideal solutions.(2/3, 2020 C, Delhi 2019, 2/5, Al 2017)
36. What type of azeotropic mixture will be formed by a solution of acetone and chloroform? Justify on the basis of strength of intermolecular interactions that develop in the solution. (Al 2019)
SA II (3 marks)
37. (a) Differentiate between Ideal solution and non-ideal solution.
(b) 30 g of urea is dissolved in 846 g of water. Calculate the vapour pressure of water for this solution if vapour pressure of pure water at 298 K is 23.8 mm Hg. (2023)
CBQ (4 marks)
38. Read the following passage carefully and answer the questions that follow:
According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this condition is fulfilled only in exceptional cases for mixtures (optical isomers, isotopic mixtures of an element, hydrocarbon mixtures). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This view is further supported by the fact that Raoult's law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
(a) Give one example of miscible liquid pair which shows negative deviation from Raoult's law. What is the reason for such deviation?
(b) (i) State Raoult's law for a solution containing volatile components.
OR
(b) (ii) Raoult's law is a special case of Henry's law. Comment.
(c) Write two characteristics of an ideal solution. (2025)
39. Read the following passage carefully and answer the questions that follow:
Raoult's law for volatile liquids states that the partial vapour pressure of each component in the solution is directly proportional to its mole fraction, whereas for a non-volatile solute, it states that the vapour pressure of a solution of a non-volatile solute is equal to the vapour pressure of the pure solvent at that temperature multiplied by its mole fraction. Two liquids A and B are mixed with each other to form a solution, the vapour phase consists of both components of the solution. Once the components in the solution have reached equilibrium, the total vapour pressure of the solution can be determined by combining Raoult's law with Dalton's law of partial pressures. If a non-volatile solute B is dissolved into a solvent A to form a solution, the vapour pressure of the solution will be lower than that of the pure solvent. The solutions which obey Raoult's law over the entire range of concentration are ideal solutions, whereas the solutions for which vapour pressure is either higher or lower than that predicted by Raoult's law are called non-ideal solutions. Non-ideal solutions are identified by determining the strength of the intermolecular forces between the different molecules in that particular solution. They can either show positive or negative deviation from Raoult's law depending on whether the A-B interactions in solution are stronger or weaker than A-A and B-B interactions.
(a) 20 mL of a liquid A was mixed with 20 mL of liquid B. The volume of resulting solution was found to be less than 40 mL. What do you conclude from the above data?
(b) Which of the following show positive deviation from Raoult's law? Carbon disulphide and Acetone; Phenol and Aniline; Ethanol and Acetone
(c) The vapour pressure of a solution of glucose in water is 750 mm Hg at 100°C. Calculate the mole fraction of solute. (Vapour pressure of water at 373 K = 760 mm Hg)
OR
(c) The boiling point of solution increases when 1 mol of NaCl is added to 1 litre of water while addition of 1 mol of methanol to one litre of water decreases its boiling point. Explain the above observations. (2023)
Relative Lowering in Vapour Pressure
MCQ
40. The relative lowering of vapour pressure of an aqueous solution containing non-volatile solute is 0-0225. The mole fraction of the non-volatile solute is
(a) 0.80
(b) 0.725
(c) 0.15
(d) 0.0225 (2024)
VSA (1 mark)
41. Define the following term:
Colligative properties (1/2, Delhi 2017)
SAI (2 marks)
42. A solution is prepared by dissolving 10 g of non-volatile solute in 200 g of water. It has a vapour pressure of 31.84 mm Hg at 308 K. Calculate the molar mass of the solute. (Vapour pressure of pure water at 308 K = 32 mm Hg) (2023)
SA II (3 marks)
43. Vapour pressure of water at 293 K is 17.536mm Hg. Calculate the vapour pressure of aqueous solution when 20 g of glucose (Molar mass = 180 g mol¹) is dissolved in 500 g of water. (2021)
44. 30 g of urea (M = 60 g mol¹) is dissolved in 846 g of water. Calculate the vapour pressure of water for this solution if vapour pressure of pure water at 298 K is 23.8 mm Hg. (3/5, Al 2017)
LA (5 marks)
45. (a) State Henry's law and mention its two applications.
(b) 5% aqueous solution of a non-volatile solute was made and its vapour pressure at 373 K was found to be 745 mm. Vapour pressure of pure water at this temperature was 760 mm. Calculate the molar mass of solute. (2020 C)
Elevation of Boiling Point
MCQ
46. The boiling point of a 0.2 m solution of a non-electrolyte in water is (K, for water = 0.52 K kg mol¯¹)
(a) 100 °C
(b) 100.52 °C
(c) 100.104 °C
(d) 100.26 °C (Term I, 2021-22)
47. Assertion (A): Elevation in boiling point is a colligative property.
Reason (R): Elevation in boiling point is directly proportional to molarity.
(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is correct, but Reason (R) is wrong statement.
(d) Assertion (A) is wrong, but Reason (R) is correct statement. (2020)
CBQ(4 marks)
48. Read the following passage carefully and answer S the questions that follow:
The cause for deviation from Raoult's law in the colligative properties of non-ideal solutions lie in the nature of interactions at the molecular level. These properties show deviations from Raoult's law due to difference in interactions between solute - solvent, solute - solute and solvent - solvent. Some liquids on mixing, form azeotropes which are binary mixtures having the same composition in liquid and vapour phase and boil at a constant temperature. In such cases, it is not possible to separate the components by fractional distillation. There are two types of azeotropes called minimum boiling azeotrope and maximum boiling azeotrope.
(a) Pure ethanol cannot be prepared by fractional distillation of ethanol-water mixture. Comment.
(b) Why does a mixture of chloroform and acetone show deviation from ideal behaviour?
(c) (i) The vapour pressure of pure benzene at a certain temperature is 1.25 atm. When 1.2 g of non-volatile, non-electrolyte solute is added to 60 g of benzene (M = 78 g mol-¹), the vapour pressure of the solution becomes 1.237 atm. Calculate the molar mass of the non-volatile solute.
OR
(c) (ii) The boiling point of benzene is 353.23 K. When 1.80 g of a non-volatile solute was dissolved in 90 g of benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of the solute. K for benzene is 2.53 K kg mol-¹. (2024)
LA (5 marks)
49. (i) Boiling point of water at 750 mm Hg pressure is 99.68 °C. How much sucrose (Molar mass = 342 g mol¹) is to be added to 500 g of water such that it boils at 100 °C? (K for water = 0.52 K kg mol-¹)
(ii) State Henry's law and write its any one application.(2024)
Depression of Freezing Point
MCQ
50. In the following diagram point 'X' represents
(a) boiling point of solution
(b) freezing point of solvent
(c) boiling point of solvent
(d) freezing point of solution. (Term I, 2021-22)
SA I (2 marks)
51. A solution containing 60 g of a non-volatile solute in 250 g of water freezes at 270.67 K. Calculate the molar mass of the solute. (Kf, of water = 1.86 K kg mol¯¹) (2024)
52. Nisha took two aqueous solutions one containing 7.5 g of urea (Molar mass = 60 g/mol) and the other containing 42.75 g of substance Z in 100 g of water, respectively. It was observed that both the solutions froze at the same temperature. Calculate the molar mass of Z. (2020)
53. Calculate the freezing point of a solution containing 60 g of glucose (molar mass = 180 g mol-¹) in 250 g of water. (Kf, of water = 1.86 K kg mol-¹) (2018)
SA II (3 marks)
54. Vapour pressure of pure water at 298 K is 24.8 mm Hg. Calculate the lowering in vapour pressure of an aqueous solution which freezes at -0.3°C. (Kf, of water1.86 K kg mol-¹) (2025)
55. A solution of glucose (molar mass = 180 g mol-¹) in water has a boiling point of 100.20 °C. Calculate the freezing point of the same solution. Molal constants for water Kf and Kb are 1.86 K kg mol-¹ and 0.512 K kg mol-¹ respectively. (2025)
56. An antifreeze solution is prepared by dissolving 31 g of ethylene glycol (Molar mass = 62 g mol-¹) in 600 g of water. Calculate the freezing point of the solution. (Kf, for water = 1.86 K kg mol-¹) (2020)
57. Calculate the mass of ascorbic acid (Molar mass 176 g mol-¹) to be dissolved in 75 g of acetic acid, to lower its freezing point by 1.5 0 C (K, 3.9 K kg mol-¹) (NCERT Intext, 2020)
58. 1.00 g of a non-electrolyte solute dissolved in 50 g of benzene lowered the freezing point of benzene by 0.40 K. The freezing point depression constant of benzene is 5.12 K kg mol-¹. Find the molar mass of the solute. (3/5, Delhi 2019)
59. A 5% solution (by mass) of cane-sugar in water has freezing point of 271 K. Calculate the freezing point of 5% solution (by mass) of glucose in water if the freezing point of pure water is 273.15 K. [Molecular masses: Glucose C6H12O6: 180; Cane-sugar C12H22O11 : 342] (NCERT, 3/5 Delhi 2019)
60. A 4% solution (w / w) of sucrose ( M = 342g mol-¹ ) in water has a freezing point of 271.15 K. Calculate the freezing point of 5% glucose (M = 180 g mol-¹) in water. (Given: Freezing point of pure water = 273.15K )(Delhi 2019)
61. A 10% solution (by mass) of sucrose in water has freezing point of 269.15 K. Calculate the freezing point of 10% glucose in water, if freezing point of pure water is 273.15 K. (Given: Molar mass of sucrose = 342 g mol-¹, molar mass of glucose = 180g mol-¹) (Delhi 2017)
LA (5 marks)
62. (i) Ishan's automobile radiator is filled with 1.0 kg of water. How many grams of ethylene glycol (Molar mass = 62 g mol-¹) must Ishan add to get the freezing point of the solution lowered to - 2.8 0C ? (Kf, for water is 1.86 K kg mol-¹)
(ii) What type of deviation from Raoult's law is shown by ethanol and acetone mixture? Give reason. (2024)
Osmosis and Osmotic Pressure
MCQ
63. An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because
(a) it gains water due to osmosis
(b) it loses water due to reverse osmosis
(c) it gains water due to reverse osmosis
(d) it loses water due to osmosis (2025)
64. Isotonic solutions have the same
(a) density
(b) refractive index
(c) osmotic pressure
(d) volume. (2024)
65. The colligative property used for the determination of molar mass of polymers and proteins is
(a) osmotic pressure
(b) depression in freezing point
(c) relative lowering in vapour pressure
(d) elevation in boiling point. (2023)
66. Assertion (A): A raw mango placed in saline solution loses water and shrivel into pickle.
Reason (R): Through the process of reverse osmosis raw mango shrivel into pickle.
(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is correct, but Reason (R) is incorrect statement.
(d) Assertion (A) is incorrect, but Reason (R) is correct statement. (Term I, 2021-22)
57. Assertion (A): Osmotic pressure is a colligative property.
Reason (R): Osmotic pressure is directly proportional to molarity.
(a) Both Assertion (A) and Reason (R) are correct statements, and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are correct statements, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is correct, but Reason (R) is incorrect statement.
(d) Assertion (A) is incorrect, but Reason (R) is correct statement, (2020)
VSA (1 mark)
68. What happens when a pressure greater than osmotic pressure is applied on the solution side separated from solvent by a semi-permeable membrane? (1/2, 2020)
69. Give reason for the following: Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers. (1/2, 2018)
70. Define the following term : Osmotic pressure (1/5, Al 2017)
SAI (2 marks)
71. Define osmotic pressure. Why is measurement of osmotic pressure method preferred for the determination of molar masses of macromolecules such as proteins and polymers? (2025)
72. A 6% solution of glucose (molar mass = 180 g mol¯¹) is isotonic with 2.5% solution of an unknown organic substance. Calculate the molecular weight of the of the unknown organic substance. (2024)
73. For a 5% solution of urea (Molar mass = 60 g/mol), calculate the osmotic pressure at 300 K. [R = 0.0821 L atm K¯¹ mol-¹](2020)
74. Give reasons:
(a) Cooking is faster in pressure cooker than in cooking pan.
(b) Red blood cells (RBC) shrink when placed in saline water but swell in distilled water. (2019)
75. (i) Out of 1 M glucose and 2 M glucose, which one has a higher boiling point and why?
(ii) What happens when the external pressure applied becomes more than the osmotic pressure of solution? (2/5, Delhi 2016)
76. Blood cells are isotonic with 0.9% sodium chloride solution. What happens if we place blood cells in a solution containing
(i) 1.2% sodium chloride solution?
(ii) 0.4% sodium chloride solution? (2/5, Delhi 2016)
SA II (3 marks)
77. At 300 K, 30 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of a glucose solution is 1.52 bar at the same temperature, what would be its concentration? (Al 2019)
LA (5 marks)
78. (ⅰ) Define reverse osmosis.
(ii) Why are aquatic species more comfortable in cold water in comparison to warm water?
van't Hoff Factor and Abnormal Molar Mass
MCQ
79. In case of association, abnormal molar mass of solute will
(a) increase
(b) decrease
(c) remain same
(d) first increase and then decrease. (2025)
80. van't Hoff factor for KCI solution assuming the complete dissociation is
(a) 1
(b) 2
(c) 0.5
(d) 1.5(2024)
VSA (1 mark)
81. Define the following term: van't Hoff factor (Delhi 2017)
82. Define the following term: Abnormal molar mass (Delhi 2017)
SAI (2 marks)
83. Predict the state of the solute in the solution in the following situations:
(a) When 'i' is found to be more than one.
(b) When 'i' is found to be less than one. (2020)
van't Hoff Factor and Relative Lowering of Vapour Pressure
SA II (3 marks)
84. The vapour pressure of a solvent at 283 K is 100 mm Hg. Calculate the vapour pressure of a dilute solution containing 1 mole of a strong electrolyte AB in 50 moles of the solvent at 283 K (assuming complete dissociation of solute AB). (2024)
van't Hoff Factor and Elevation of Boiling Point
VSA(1 mark)
85. Give reason for the following:
Elevation of boiling point of 1 M KCI solution is nearly double than that of 1 M sugar solution. (1/2, 2018)
SAI (2 marks)
86. Give reasons:
(i) 0.1 M KCI has higher boiling point than 0.1 M glucose.
(ii) Meat is preserved for a longer time by salting.
SAII (3 marks)
87. Calculate elevation of the boiling point of the solution when 2 g of MgSO4, (molar mass = 120g / mol) was dissolved in 100 g of water, assuming MgSO4 undergoes complete dissociation. (Kf, for water = 0.52 K kg/mol) (2024)
88. Give reasons:
(a) Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.
(b) Aquatic animals are more comfortable in cold water than in warm water.
(c) Elevation of boiling point of 1 M KCI solution is nearly double than that of 1 M sugar solution. (2023)
89. (a) Out of 0.1 molal aqueous solution of glucose and 0.1 molal aqueous solution of KCI, which one will have higher boiling point and why?
(b) Predict whether van't Hoff factor, (i) is less than one or greater than one in the following:
(i) CH3COOH dissolved in water
(ii) CH3COOH dissolved in benzene (2019)
90. Calculate the boiling point elevation for a solution prepared by adding 10 g of CaCl2, to 200 g of water. (Kf, for water = 0.52 K kg/mol, molar mass of CaCl₂ = 111gmol-1) (3/5, Al 2017)
91. Calculate the boiling point of solution when 4 g of MgSO4 (M = 120g mol-1) was dissolved in 100 g of water, assuming MgSO4, undergoes complete ionization. (Kb for water = 0.52Kkg mol-1) (Al 2016)
LA (5 marks)
92. (i) Why is boiling point of 1 M NaCl solution more than that of 1 M glucose solution?
(ii) A non-volatile solute X (molar mass = 50g mol-1) when dissolved in 78 g of benzene reduced its vapour pressure to 90%. Calculate the mass of X dissolved in the solution.
(iii) Calculate the boiling point of elevation for a solution prepared by adding 10 g of MgCl2 to 200 g of water assuming MgCl2, is completely dissociated. (Kb, for water 0.512 K kg mol-1, molar mass MgCl₂ = 95 g mol-1) (2023)
van't Hoff Factor and Depression of Freezing Point
MCQ
93. The freezing point of one molal KCI solution, assuming KCI to be completely dissociated in water, is (Kf, for water = 1.86 K kg mol-1)
(a) - 3.720C
(c) - 1.860C
(b) 3.72 0C
(d) 2.72 0C (2025)
94. Out of the following 1.0 M aqueous solutions which one will show largest freezing point depression?
(a) NaCl
(b) Na2SO4
(c) C6H12O6
(d) Al2(SO4)3 (2023)
SA II (3 marks)
95. When 19.5 g of F-CH2-COOH (molar mass = 78 g mol-¹) is dissolved in 500 g of water, the depression in freezing point is observed to be 1°C. Calculate the degree of dissociation of F-CH2-COOH. [Given: Kf, for water = 1.86 K kg mol-¹] (2023, 3/5, 2020)
96. The freezing point of a solution containing 5 g of benzoic acid (M = 122 g mol-¹) in 35 g of benzene is depressed by 2.94 K. What is the percentage association of benzoic acid if it forms a dimer in solution? (K, for benzene = 4.9 K kg mol-¹) (2020)
97. A 0.01 m aqueous solution of AlCl3 freezes at -0.068 °C. Calculate the percentage of dissociation. [Given: Kf, for water = 1.86 K kg mol¹] (2020)
98. Calculate the freezing point of solution when 1.9 g of MgCl2 (M = 95 g mol-¹) was dissolved in 50 g of water, assuming MgCl₂ undergoes complete ionization. (Kf, for water = 1.86 K kg mol-¹) (Delhi 2016)
99. When 2.56 g of sulphur was dissolved in 100 g of CS2 the freezing point lowered by 0.383 K. Calculate the formula of sulphur (Sx). (Kf, for CS2 = 3.83 K kg mol-¹, atomic mass of sulphur = 32 g mol-¹) (3/5, Delhi 2016)
LA (5 marks)
100. (i) Predict whether van't Hoff factor will be less or greater than one, when ethanoic acid is dissolved in benzene.
(ii) Define ideal solution.
(iii) Calculate the mass of CaCl₂ (molar mass = 111 g mol-¹) to be dissolved in 500 g of water to lower its freezing point by 2K, assuming that CaCl₂ undergoes complete dissociation. (K, for water = 1.86 K kg mol-¹) (2024)
101. (a) Give two differences between ideal and non-ideal solutions.
(b) Calculate the amount of NaCl (M = 58.5 g mol-¹) that must be added to 100 g of water so that freezing point is depressed by 2 K. Kf, for water is 1.86 K/m. (2020)
102. (a) Write two characteristics of non-ideal solution.
(b) 2 g of benzoic acid (C6H5COOH) dissolved in 25 g of benzene shows a depression in freezing point equal to 1.62 K. Molal depression constant for benzene is 4.9 K kg mol-¹. What is the percentage association of acid if it forms dimer in solution? (2019)
van't Hoff Factor and Osmotic Pressure
SAII (3 marks)
103. An aqueous solution of NaOH was made and its molar mass from the measurement of osmotic pressure at 27°C was found to be 25 g mol-¹. Calculate the percentage dissociation of NaOH in this solution. [Atomic mass: Na = 23 u, O = 16 u, H = 1 u] (2025)
104. (a) Find the value of van't Hoff factor for acetic acid in benzene as per the given equation: 2CH3COOH(CH3COOH)2, assuming its complete association.
(b) Osmotic pressure of a solution containing 3.5 g of dissolved protein in 0.05 L of a solution is 0.035 atm at 310 K. Calculate the molar mass of the protein. (R = 0.0821 L atm K-¹ mol-¹) (2023)
105. A solution contains 5.85 g NaCl (Molar mass = 58.5 g mol-¹) per litre of solution. It has an osmotic pressure of 4.75 atm at 27°C. Calculate the degree of dissociation of NaCl in this solution. (Given: R = 0.082 L atm K-¹ mol-1)
106. A solution 0.1 M of Na2SO4 is dissolved to the extent of 95%. What would be its osmotic pressure at 27°C? (R = 0.0821 L atm K-¹ mol-¹) (3/5, 2020)
107. (a) Draw the graph between vapour pressure and temperature and explain the elevation in boiling point of a solvent in solution.
(b) Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litres of water at 25°C assuming it to be completely dissociated. (Atomic masses : K = 39 u, S = 32 u, O = 16 u) (2019)
LA (5 marks)
108. (i) Why is the value of van't Hoff factor for ethanoic acid in benzene close to 0.5?
(ii) Determine the osmotic pressure of a solution prepared by dissolving 2.32 × 10-2 g of K₂SO₄ in 2 L of solution at 25°C, assuming that K₂SO₄ is completely dissociated.
(iii) When 25.6 g of sulphur 25.6 g of sulphur was dissolved in 1000 g of benzene, the freezing point lowered by 0.512 K. Calculate the formula of sulphur (S). (Kf for benzene = 5.12 K kg mol-¹, Atomic mass of sulphur = 32 g mol-¹) (2023)
Chemical kinetics
CHEMISTRY
Class 12
Time: 90min Max. Marks: 35
Section-A Question 1 to 8 are multiple choice questions. Only one of the choices is correct. Select and write the correct choice as well as the answer to these questions.
1. The half life Pd of a 1st order reaction is 60minutes the percentage of reactant left after 240 minutes.
(a) 12.5% (b) 25% (c) 6.25% (d) 3.75%
2. The graph which represents zero order
3. The role of a catalyst in a reaction is
(a) To accelerate the rate of reaction
(b) To retard the rate of reaction
(c) To lower the activation energy
(d) None
4. A first order reaction has a rate constant 1.15sec-1 if 5gm of reactant reduced to 3gm. The time period required is
(a) 250 sec (b) 300 sec
(c) 400sec (d) 275 sec
5. In a reaction A + B product
[A] [B] rate – (mol litre-1sec-1)
0.20 0.30 5.0710-5
0.20 0.10 5.0710-5
0.40 0.05 1.4310-3
On the basis of above data find order of reaction
(a) 3/2 (b) 2/3 (c) 5/2 (c) ½
6. If in a chemical reaction A + B + C product when A is 1st order B in IInd order and C in zero order if concern of each reactant is doubled then rate of reaction becomes
(a) r2 = 4r1 (b) r2 = 8r1
(c) r2 = 16r1 (d) r2 = 2r1
7. Molecularity of reaction is applicable for only
(a) elementary reactions (b) complex reaction
(c) Parallel reactions (d) Consecutive reaction
8. For which part of completion of 1st of order of reaction is ten times of half life period
(a) 90% (b) 99% (c) 99.9% (d) 99.99%
Section-B Question No. 9 to 11 are very short answer questions carrying 2 marks each.
9. Define the following:
a) Activation Energy
b) Threshold energy
10. Difference between rate of reaction and rate constant of reaction.
11. Write units of rate constants for zero order and for the second order reactions if the concentration is expressed in mol L-1 and time in second.
Section-C Question No. 12 to 15 are short answer questions, carrying 3 marks each.
12. The rate constant of a first order reaction becomes 5 times when the temperature is raised from 350K to 400K. Calculate the activation energy for the reaction.
13. How will the rate of reaction be affected when
i) Surface area of reactant is reduced,
ii) Catalyst is added in a reversible reaction, and
iii) Temperature of the reaction is increased?
14. A reaction is first order in A and second in B:
i) Write the differential rate equation.
ii) How is the rate affected on increasing the concentration of B three times?
iii) How is the rate affecter when the concentration of both A and B are doubled.
15. Account for the following:
i) The rate of a reaction does not remain constant throughout the course of reaction.
ii) The boiling of an egg or cooking of rice is an open vessel takes more time in hilly areas.
iii) In some cases it is fond that a large number of colliding molecules have energy more than the threshold value, yet the reaction is slow.
Section D Question No. 16 is a case-based/data -based question carrying 4 marks.
16. Read the passage given below and answer the questions that follow :
The rate of a chemical reaction is expressed either in terms of decrease in the concentration of reactants or increase in the concentration of a product per unit time. Rate of the reaction depends upon the nature of reactants, concentration of reactants, temperature, presence of catalyst, surface area of the reactants and presence of light. Rate of reaction is directly related to the concentration of reactant. Rate law states that the rate of reaction depends upon the concentration terms on which the rate of reaction actually depends, as observed experimentally. The sum of powers of the concentration of the reactants in the Rate law expression is called order of reaction while the number of reacting species taking part in an elementary reaction which must collide simultaneously in order to bring about a chemical reaction is called molecularity of the reaction. Answer the following questions:
(a) (i) What is a rate determining step?
(ii) Define complezx reaction.
(b) What is the effect of temperature on the rate constant of a reaction?
OR,
Why is molecularity applicable only for elementary reactions whereas order is applicable for elementary as well as complex reactions?
(c) The conversion of molecule X to Y follows second-order kinetics. If the concentration of X is increased 3 times, how will it affect the rate of formation of Y?
Section-E Question No. 17 is a long answer type question carrying 5 marks.
17. (a) Define order of reaction. How does order of a reaction differ from molecularity for a complex reaction?
(b) A first order reaction is 50% complete in 25 minutes. Calculate the time for 80% completion of the reaction.
OR,
Derive an expression for rate constant of first order reaction.
ELECTRO CHEMISTRY
Class 12
Time: 90min Max. Marks: 35
Section-A Question 1 to 8 are multiple choice questions. Only one of the choices is correct. Select and write the correct choice as well as the answer to these questions.
1. The difference between the electrode potentials of two electrodes when no current is drawn through the cell is called
(a) Cell potential
(b) Cell emf
(c) Potential difference
(d) Cell voltage
2. The number of Faraday's require to reduce one mole of Cu2+ to metallic copper is :
(a) One (b) Two (c) three (d) four
3. The unit of equivalent conductance is :
(a) ohm-¹ cm² equivalent 1 (b) ohm-¹ cm² g-1
(c) ohm cm² equivalent-1 (d) ohm-¹ mol-1
4. The quantity of electricity required to deposit 1.15 g of sodium from molten NaCl
(a) 1 F (b) 0.5 F (c) 0.05 F (d) 1.5 F
5. The cell constant of a conductivity cell :
(a) changes with change of electrolyte.
(b) changes with change of concentration of electrolyte.
(c) changes with temperature of electrolyte.
(d) remains constant for a cell.
6. Which of the following cell is used in inverter?
(a) Fuel cell
(b) Mercury cell
(c) Lead storage cell
(d) Dry cell
7. Assertion(A): Conductivity decreases with decrease in concentration of electrolyte.
Reason(R): Number of ions per unit volume that carry the current in a solution decreases on dilution.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion & reason both are false.
8. Assertion(A): Current stops flowing when Ecell = 0.
Reason(R): Equilibrium of the cell reaction is attained.
a) Both assertion and reason are true and reason is the correct explanation of assertion.
b) Both assertion and reason are true but reason is not the correct explanation of assertion.
c) Assertion is true but reason is false.
d) Assertion & reason both are false.
Section-B Question No. 9 to 11 are very short answer questions carrying 2 marks each.
9. A current of 1.5 A was passed through an electrolytic cell containing AgNO3 solution with inert electrodes. The mass of silver deposited was 1.50g. How long did the current flow?
10. The conductivity of a 0.01M solution of acetic acid at 298K is 1.65 x10-4Scm-1. Calculate the molar conductivity of the solution.
11. State the Kohlrausch law of independent migration of ions.
Section-C Question No. 12 to 15 are short answer questions, carrying 3 marks each.
12. Define conductivity, molar conductivity & cell potential.
13. Explain Faradys First law of electrolysis.
14. Define fuel cell. What advantage of fuel cell have over primary & secondary cell. Write CH4-O2 fuel reaction.
15. Calculate the emf of following cell at 298K :
Mg(s)|Mg2+(0.1M)|| Cu2+(0.0001)|Cu(s). [Given E0cell = 2.71V]
Section D Question No. 16 is a case-based/data -based question carrying 4 marks.
16. During the construction of public building the contractor intends to fix iron frames for windows and railings to reduce the cost of construction. After due considerations, it is finally recommended to use aluminium for window and steel railings instead of iron.
(a) As a chemistry student, do you agree with the new recommendation.
(b) Name the phenomenon in which iron undergoes.
(c) Give one reason in which aluminium and steel railing is good as compared to iron railing.
Or,
(c) why steel railing does not undergoes corrosion.
Section-E Question No. 17 is a long answer type question carrying 5 marks.
17. (a) Define the following terms
(i) Primary batteries
(ii) Corrosion
(b) The resistance of a conductivity cell containing 0.0001M KCl solution at 298K is 1500ohm. What is the cell constant if conductivity of 0.0001M KCl solution at 298K is 0.146 x 10-3 Scm-1?
Or,
(a) Calculate E0cell for the following reaction at 298K:
2Al(s) + 3Cu2+(0.01M) 2Al3+(0.01M) + 3Cu(s) Given: Ecell = 1.98V
(b) Define electrochemical cell. What happens if external potential applied becomes greater than E0cell of electrochemical cell?
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT: 09: CO-ORDINATION COMPOUNDS
Long Answer Question
1. Discuss the following terms:
a) Co-ordination number
b) Effective atomic number
c) Central metal atom/ion
d) Double Salts
2. Explain on the basis of valence bond theory that [Ni(CN)4]2- ion with square planar structure is diamagnetic and the [NiCl4]2- ion with tetrahedral geometry is paramagnetic.
3. What is co-ordination compound? What is the difference between co-ordination compound and double salt?
4. Explain the following:
a) Cationic complex
b) Central atomic ion
5. Write oxidation state, hybridization, geometry and magnetic behaviour of some following co-ordination compounds.
a) [Ni(CO)4]
b) [Ni(CN)4]2-
c) [NiCl4]2-
d) [CuCl4]2-
e) [Fe(CN)6]3-
f) [Fe(CN)6]4-
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT: 06: General Principles & Processes of Isolation of Elements
Short Answer Question
1. Explain with suitable example Mineral Ore
2. Give the name and chemical composition of important ores of:
a) Aluminium
b) Iron
c) Copper
d) Calcium
e) Mercury
f) Magnesium
g) Zinc
h) Silver
i) Gold
3. Differentiate the Flux and Slag giving suitable example.
4. What do you mean by concentration of ore? Describe the following:
a) Froth floatation process
b) Magnetic process
5. What is gravity separation or levingation process?
6. What is Bessemerization?
7. What is the role of depressant in froth floatation process?
8. What is the role of flux in metallurgical process?
9. Why is Chalcocite roasted and not calcite in the recovery of copper?
10. How is bauxite generally concentrated?
11. Define smelting and give example.
12. How is wrought iron prepared from cast iron?
13. Which method is usually employed for purifying the following metals? Mention the principle.
a) Iron
b) Nickel
14. What is electrorefining?
15. State the role of silica in the metallurgy of copper.
16. What is significance of leaching in the extraction of aluminium?
17. Describe the role of NaCN in the extraction of silver from silver ore.
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 04 : CHEMICAL KINETICS
Long answer Question
1. What is Arrhenius Equation? How does it help in calculating the activation energy?
2. What is catalyst? Explain the action of catalyst on a reaction.
3. Explain molecularity and order of reaction and distinguish between them.
4. What do you mean by zero order reaction? Derive the expression for integrated rate equations for zero order reactions. How half life of zero order reactions is related with rate constant?
5. Derive an expression for rate constant of first order reaction.
6. Explain half life period for first order reaction and establish the relation between half-life period and average life period.
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 04 : CHEMICAL KINETICS
Short answer Question
1. What is activation energy? How is the rate constant of a reaction is related with activation energy?
2. Identify the reaction order from each of the following rate constant.
(a) k = 2.3 x 10-5 L mol-1 s-1
(b) k = 3 x 10-4 s-1
3. Explain the effect of concentration and temperature on the rate of reaction.
4. What is pseudo first order reaction?
5. In a first order reaction, the units of the rate constant do not depend upon the concentration of the reactants. Justify.
6. What do you understand by elementary reaction?
7. How is half life period related to initial concentration if the reaction as of zero order, first order, second order & nth order
8. Give one example of zero order reaction and first order reaction.
9. Write the slope value obtained in the plot of ln[R] vs time for a first order reaction.
10. What is half life period of a reaction. Prove that half life period of a first order reaction is independent of initial concentration of reactant.
11. What is rate law?
12. Explain why the rate of a reaction increases with rise in temperature.
13. The rate of reaction is not constant in whole reaction. Why?
14. Define molecularity of reaction & Threshold energy.
15. What is rate of reaction?
16. What do you mean by rate of instantaneous reaction?
17. Calculate the over all order of a reaction which has the rate expression:
a) Rate = K[A]1/2[B]3/2
b) Rate = K[A]3/2[B]-1
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 03 :ELECTRO CHEMISTRY
1. What do you understand by secondary cell?
2. What is the difference between electrolytic cell and electrochemical cell?
3. What do you mean by Primary cell(Battery)?
4. What is cell constant?
5. Write the chemical equation of charging and discharging of lead storage battery.
6. Electrolysis of concentrated aqueous soltion of NaF does not give F2, why?
7. Explain resistivity(specific resistance).
8. Define specific conductance(conductivity) and equivalent conductance.
9. Why does conductivity of solution of electrolyte increase by heating?
10. Why does the conductivity of a solution decreases with dilution?
11. Explain molar conductivity. What is its unit?
12. What is electrode potential, standard electrode potential and standard hydrogen electrode?
13. State Faraday’s 1st law of electrolysis.
14. Where is electrolysis used?
15. State Faraday’s 2nd law of electrolysis.
16. Explain the reaction involved in a Galvanic cell. How is Daniell cell represented?
17. What is a fuel cell? Give the electrode reactions of hydrogen oxygen fuel cell.
18. Write down the half cell reaction and cell reaction for the Daniell cell Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s)
19. Write the product of electrolysis
i) Fused sodium chloride and
ii) An aqeous solution of sodium chloride (Brine solution)
Chemistry practice set CBSE CLASS XII
UNIT 02 SOLUTION
Time: 90min Max. Marks: 35
Section-A Question 1 to 8 are multiple choice questions. Only one of the choices is correct. Select and write the correct choice as well as the answer to these questions.
1. If V.P. of pure benzene is 0.85 bar. When a non- volatile solute of mass 0.5gm added in 39gm of benzene then V.P. of solution is found to be 0.845 bar. The molar mass of solute is
(a) 80 gm
(b) 170 gm
(c) 190 gm
(d) 199 gm
2. Isotonic solutions have the same
(a) Density
(b) Refractive index
(c) Osmotic Pressure
(d) volume
3. The freezing point of 0.1 molal aquous solution would be (Kf = 1.86 kg K/mol)
(a) 0.186 0C
(b) – 0.186 0C
(c) – 1.86 0C
(d) 0.0186 0C
4. The solution which has maximum boiling point
(a) 0.1 m urea
(b) 0.1 m glucose
(c) 0.1 m sucrose
(d) 0.1 m naphthalene
5. Boiling point of H2O at 750 mm of Hg is 99.630C . How much sucrose should be added in 500gm of water that it boils at 1000C
(a) 126 gm
(b) 125 gm
(c) 122gm
(d) 28 gm
6. A solution containing 10% glucose and 5% urea in 100 ml of solution at 270C. The osmotic pressure of solution is
(a) 3.33 atm
(b) 33.33 atm
(c) 6.66 atm
(d) none
7. Two elements of A & B form compound having formula AB2 and AB4 when dissolve in 20gm of benzene, 1gm of AB2 lower the F.p by 2.3K and 1gm of AB4 lowers by 1.3K (KF =5.1 K Kp mol-1) atomic mass of A is
(a) 25.58 amu
(b) 55.5 amu
(c) 35.55 amu
(d) 20.58 amu
8. Assertion : A non volatile solution is mixed in a solution then elevation in boiling point and depression in freezing point both are 2 K.
Reason : Elevation in boiling point and depression in freezing point both depend on melting point of nonvolatile solute.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of assertion.
(c) If Assertion is true but reason is false.
(d) If Assertion & reason both are false.
Section-B Question No. 9 to 11 are very short answer questions carrying 2 marks each.
9. Two solutes ‘X’ and ‘Y’ in equal amounts are dissolved separately in 10 moles of solvent C. If ‘X’ molecule is heavier than ‘Y’ molecule, which solution will have larger relative lowering of vapour pressure?
10. Define the following terms
(a) Osmotic pressure
(b) Ideal solution.
11. State Henry’s law. What is effect of temperature on the solbility of a gas in liquid?
Section-C Question No. 12 to 15 are short answer questions, carrying 3 marks each.
12. Calculate the mass of non-volatile solute (molar mass 40) which should be dissolved in 114g octane to reduce the vapour pressure to 80%.
13. Give reasons of the following:
(a) Measurement of osmotic pressure method is preferred for the determination of molar mass of macro-molecules such as proteins and polymers.
(b) Aquatic animals are more comfortable in cold water than warm water.
(c) Elevation of boiling point of 1 M KCl solution is nearly double than that of 1M sugar solution.
14. What do you understand by lowering of vapour pressure of a solvent? What is relation between relative lowering of vapour pressure and molecular mass of solute and solvent?
15. Define following terms
(a) Molarity
(b) Reverse Osmosis
(c) Vapour pressure
Section D Question No. 16 is a case-based/data -based question carrying 4 marks.
16. Colligative properties depend on the number of solute particles irrespective on their nature, they are, relative lowering of vapour pressure, elevation in boiling point, depression in freezing point and osmotic pressure. Abnormal molecular mass and colligative properties are observed in some cases where the experimental and theoretical vales differ considerably. Due to dissociation of solute in water the number of particles in the solution increases, resulting in increase in experimental vales, since
Colligative properties
Experimental molecular mass < Normal molecular mass
Answer the following questions:
(a) Why is osmotic pressure considered as a colligative property?
(b) What happens when a pressure greater than osmotic pressure is applied on the solution side separated from solvent by a semi-permeable membrane?
(c) Write two advantages of osmotic pressure method over boiling point elevation method for determining molecular masses.
Or,
Calculate the boiling point of solution when 4g of MgSO4(M = 120) was dissolved in 100g of water, assuming MgSO4 undergoes complete ionization. (Kb for water = 0.52 K Kg mol-1)
Section-E Question No. 17 is a long answer type question carrying 5 marks.
17. (i) Which type of deviation is shown by the solution formed by mixing cyclohexane and ethanol?
(ii) 18g of glucose is dissolved in 1Kg of water in a saucepan. At what temperature will we water boil? Kb for water = 0.52 K Kg mol-1
(iii) A and B liquids on mixing produced a warm solution. Which type of deviation is there and why?
Or,
(a) Why is camphor preferred as a solvent in determination of depression in freezing point?
(b) Aquatic species are more comfortable in cold water rather than warm water. Why?
(c) A 10% solution by mass of sucrose in water has freezing point of 269.15K. Calculate the freezing point of 10% glucose in water, if freezing point of pure water is 273.15K.
Chemistry Guss Question for BSEB 2026 Class 12
UNIT : 02 :Solution
Long Answer Question
1. Explain the following terms.
i) Mole fraction
ii) Molality
iii) Molarity
iv) Normality
v) Osmosis
2. What is elevation of boiling point? Show it is a colligative property. Find relation between elevation of boiling point and molar mass of solute.
3. What is difference between osmosis and diffusion?
4. What do you understand by lowering of vapour pressure of a solvent? Write down the Raoult’s law of lowering of vapour pressure and what is relation between relative lowering of vapour pressure and molecular mass of solute and solvent?
5. Explain the following terms:
i) Abnormal colligative property
ii) Van’t Hoff factor
iii) Henry law
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 02 : Solution
Short Answer Question
1. Why do gases always tend to be less soluble in liquids as the temperature is raised?
2. What role does the molecular interaction play in solution of alcohol and water?
3. What is azeotropic mixture(azeotropes)? What are their types?
4. Define abnormal molecular mass and degree of dissociation.
5. What is osmotic pressure? Why does osmotic pressure become abnormal?
6. Why does vapour pressure of a liquid decreases with addition of non-volatile solute?
7. What is reverse osmosis? What is its use?
8. Explain positive and negative deviation from ideal solution.
9. How is molarity of solution different molality?
10. State colligative properties of dilute solution. Write down the different types of colligative properties.
11. State and explain the ideal solution
12. What are the factors affecting the solubility of gas?
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Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 05 :SURFACE CHEMISTRY
SHORT ANSWER QUESTIONS
1. Write a short note on adsorption. How does it differ from absorption?
2. How does extent of adsorption depend upon surface area of the adsorbent?
3. What role does adsorption play in heterogeneous catalysis?
4. Write a short note on colloids.
5. How are the colloidal solutions classified on the basis of dispersed phase and dispersion medium?
6. How will you prepare a colloidal solution of gold? How is it stabilised?
7. How do pressure and temperature influence the adsorption of a gas on a solid?
8. What is the difference between multimolecular and macro-molecular colloids?
9. What is the difference between a sol and a gel? What are emulsions?
10. How will you distinguish between physical adsorption and chemical adsorption?
11. What do you mean by activity and selectivity of catalysts?
12. What are emulsions? What are their different types? Give example of each type.
13. How will you obtain a colloidal solution of arsenious sulphide?
14. Describe a chemical method for the preparation of sol of sulphur and platinum.
15. How does chemical adsorption of a gas on a solid vary with temperature?
16. What are the difference between physisorption and chemisorption?
17. State the following(i) Adsorbent (ii) Adsorbate (iii) Adsorption. Give reason why a finely divided substance is more effective as an adsorbent.
18. What are the applications of adsorption?
19. What role does adsorption play in heterogeneous catalysis?
20. What brief note on (i) Coagulation (ii) Gold number (iii) Hardy-Schulze law.
21. Explain the following terms (i) Lyophobic sols (ii) Gold number (iii) Peptisation.
22. What is Tyndall effect?
23. Explain the following terms with suitable examples (i) Gel (ii) Aerosol (iii) Hydrosol.
24. What is an emulsion? Give one example.
25. Explain the following terms (i) Electro-dialysis (ii) Electrokinetic potential (iii) Phases of a colloidal solution.
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 05 :SURFACE CHEMISTRY
VERY SHORT ANSWER QUESTIONS
1. What is the function of emulsifying agent?
2. How does adsoption of a gas on a solid surface vary with temperature?
3. Define gold number and coagulation value.
4. What is difference between sols and gels?
5. Indicate chemical reaction involving homogeneous catalyst.
6. What type of solution is obtained by adding aq NaCl to benzene?
7. What type of colloidal is formed when white of an egg is mixed with water?
8. What is the difference between Macromolecular and Associated colloids?
9. What is the effect of temperature on adsorption?
10. Give an example of an associated colloid.
11. What is an adsorption isotherm?
12. Give one example each of oil in water and water in oil emulsions.
13. What are aerosols?
14. Why adsorption is always exothermic?
15. What is demulsification?
16. Why lyphillic colloids are more stable than lyophobic colloidal sols?
17. What is Hardy Schulze's rule?
18. Define gold number.
19. What is the effect of temperature on adsorption?
20. What is heterocatalysis?
21. Define physisorption.
22. What is dialysis?
23. What is Brownian movement?
24. Define flocculation value.
Chemistry Guss Question for BSEB 2026 CLASS12
UNIT : 01 : SOLID STATE
SHORT ANSWER QUESTIONS
1. What do you mean by point defect in a crystal?
Or, Define point defect.
2. Why is Frenkel defect produced in solid crystal?
3. Why does white ZnO(s) becomes yellow upon heating?
4. What are F- centres in a crystal?
5. Why does table salt, some time appear yellow in colour?
6. Why are solids are incompressible (rigid)?
7. A solid is made of two elements P & Q. Atoms of Q are in ccp arrangement while atoms of P occupy all the tetrahedral sites. What is the formula of the compound?
8. A group 14 element is to be converted into n-type semiconductor by doping it with a suitable impurity. To which group should this impurity belong?
9. Give the significance of a ‘lattice point.’
10. What type of solids are electrical conductors, malleable & ductile?
11. Why do solids have a definite volume?
12. What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?
13. Why are ionic solids behave as conductor in molten state and not in the solid state? Explain.
14. Glass is assumed to be a super cooled liquid. Why?
Chemistry Guss Question for BSEB 2026 CLASS 12
UNIT : 01 : SOLID STATE
LONG ANSWER QUESTIONS
1. What do you understand by crystal defects in solids? What is stoichiometric defect? Explain the following types of cystal defects:
i) Vacancy defect
ii) Interstitial defect
iii) Non-stoichiometric defect
iv) Impurity defect
2. What is the difference between Schottky defect & Frenkel defect?
3. How will you distinguish between crystalline solid & amorphous solid based on their properties?
4. What do you understand by magnetic property of solids. Explain the following
i) Paramagnetism
ii) Diamagnetism
iii) Ferromagnetism
iv) Ferrimagnetism
v) Antiferromagnetism
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