Chapter 2 – Solutions

Class 12 Chemistry · 50 questions · 50 with answers

Questions

Q1Multiple choice

Which of the following units is useful in relating concentration of solution with its vapour pressure?

(i)mole fraction
(ii)parts per million
(iii)mass percentage
(iv)molality

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(i) mole fraction

Q2Multiple choice

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?

(i)Sugar crystals in cold water.
(ii)Sugar crystals in hot water.
(iii)Powdered sugar in cold water.
(iv)Powdered sugar in hot water.

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(iv) Powdered sugar in hot water.

Q3Multiple choice

At equilibrium the rate of dissolution of a solid solute in a volatile liquid solvent is __________.

(i)less than the rate of crystallisation
(ii)greater than the rate of crystallisation
(iii)equal to the rate of crystallisation
(iv)zero

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(iii) equal to the rate of crystallisation

Q4Multiple choice

A beaker contains a solution of substance ‘A’. Precipitation of substance ‘A’ takes place when small amount of ‘A’ is added to the solution. The solution is _________.

(i)saturated
(ii)supersaturated
(iii)unsaturated
(iv)concentrated

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(ii) supersaturated

Hint: Hint : If added substance dissolves, the solution is unsaturated. If it does not dissolve solution is saturated. If precipitation occurs solution is supersaturated.

Q5Multiple choice

Maximum amount of a solid solute that can be dissolved in a specified amount of a given liquid solvent does not depend upon ____________.

(i)Temperature
(ii)Nature of solute
(iii)Pressure
(iv)Nature of solvent

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(iii) Pressure

Q6Multiple choice

Low concentration of oxygen in the blood and tissues of people living at high altitude is due to ____________.

(i)low temperature
(ii)low atmospheric pressure
(iii)high atmospheric pressure
(iv)both low temperature and high atmospheric pressure

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(ii) low atmospheric pressure

Hint: Hint : Body temperature of human beings remains constant.

Q7Multiple choice

Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?

(i)Methanol and acetone.
(ii)Chloroform and acetone.
(iii)Nitric acid and water.
(iv)Phenol and aniline.

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(i) Methanol and acetone.

Q8Multiple choice

Colligative properties depend on ____________.

(i)the nature of the solute particles dissolved in solution.
(ii)the number of solute particles in solution.
(iii)the physical properties of the solute particles dissolved in solution.
(iv)the nature of solvent particles.

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(ii) the number of solute particles in solution.

Q9Multiple choice

Which of the following aqueous solutions should have the highest boiling point?

(i)1.0 M NaOH
(ii)1.0 M Na2SO4
(iii)1.0 M NH4NO3
(iv)1.0 M KNO3

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(ii) 1.0 M Na2SO4

Q10Multiple choice

The unit of ebulioscopic constant is _______________. –1 –1

(i)K kg mol or K (molality) –1 –1
(ii)mol kg K or K (molality) –1 –1 –1 –1
(iii)kg mol K or K (molality) –1
(iv)K mol kg or K (molality)

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(i) K kg mol or K (molality) –1 –1

Q11Multiple choice

In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl2 solution is _____________.

(i)the same
(ii)about twice
(iii)about three times
(iv)about six times

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(iii) about three times

Q12Multiple choice

An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because _____________.

(i)it gains water due to osmosis.
(ii)it loses water due to reverse osmosis.
(iii)it gains water due to reverse osmosis.
(iv)it loses water due to osmosis.

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(iv) it loses water due to osmosis.

Q13Multiple choice

At a given temperature, osmotic pressure of a concentrated solution of a substance _____________.

(i)is higher than that at a dilute solution.
(ii)is lower than that of a dilute solution.
(iii)is same as that of a dilute solution.
(iv)cannot be compared with osmotic pressure of dilute solution.

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(i) is higher than that at a dilute solution.

Q14Multiple choice

Which of the following statements is false?

(i)Two different solutions of sucrose of same molality prepared in different solvents will have the same depression in freezing point.
(ii)The osmotic pressure of a solution is given by the equation Π = CRT ( where C is the molarity of the solution).
(iii)Decreasing order of osmotic pressure for 0.01 M aqueous solutions of barium chloride, potassium chloride, acetic acid and sucrose is BaCl2 > KCl > CH3COOH > sucrose.
(iv)According to Raoult’s law, the vapour pressure exerted by a volatile component of a solution is directly proportional to its mole fraction in the solution.

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(i) Two different solutions of sucrose of same molality prepared in different solvents will have the same depression in freezing point.

Q15Multiple choice

The values of Van’t Hoff factors for KCl, NaCl and K2SO4, respectively, are _____________.

(i)2, 2 and 2
(ii)2, 2 and 3
(iii)1, 1 and 2
(iv)1, 1 and 1 19 Solutions

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(ii) 2, 2 and 3

Q16Multiple choice

Which of the following statements is false?

(i)Units of atmospheric pressure and osmotic pressure are the same.
(ii)In reverse osmosis, solvent molecules move through a semipermeable membrane from a region of lower concentration of solute to a region of higher concentration.
(iii)The value of molal depression constant depends on nature of solvent.
(iv)Relative lowering of vapour pressure, is a dimensionless quantity.

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(ii) In reverse osmosis, solvent molecules move through a semipermeable membrane from a region of lower concentration of solute to a region of higher concentration.

Q17Multiple choice

Value of Henry’s constant KH ____________.

(i)increases with increase in temperature.
(ii)decreases with increase in temperature.
(iii)remains constant.
(iv)first increases then decreases.

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(i) increases with increase in temperature.

Q18Multiple choice

The value of Henry’s constant KH is _____________.

(i)greater for gases with higher solubility.
(ii)greater for gases with lower solubility.
(iii)constant for all gases.
(iv)not related to the solubility of gases.

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(ii) greater for gases with lower solubility.

Q19Multiple choice

Consider the Fig. 2.1 and mark the correct option.

This question refers to a figure in the original PDF.

(i)water will move from side (A) to side (B) if a pressure lower than osmotic pressure is applied on piston (B).
(ii)water will move from side (B) to side (A) if a pressure greater than osmotic pressure is applied on piston (B).
(iii)water will move from side (B) to side (A) if a pressure equal to osmotic pressure is applied on piston (B).
(iv)water will move from side (A) to side (B) if pressure equal to osmotic pressure is applied on piston (A). Fig. 2.1

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(ii) water will move from side (B) to side (A) if a pressure greater than osmotic pressure is applied on piston (B).

Q20Multiple choice

We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentrations 0.1M, 0.01M and 0.001M, respectively. The value of van’t Hoff factor for these solutions will be in the order______.

(i)iA < iB < iC
(ii)iA > iB > iC
(iii)iA = iB = iC
(iv)iA < iB > iC

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(iii) iA = iB = iC

Q21Multiple choice

On the basis of information given below mark the correct option. Information: (A) In bromoethane and chloroethane mixture intermolecular interactions of A–A and B–B type are nearly same as A–B type interactions. (B) In ethanol and acetone mixture A–A or B–B type intermolecular interactions are stronger than A–B type interactions. (C) In chloroform and acetone mixture A–A or B–B type intermolecular interactions are weaker than A–B type interactions.

(i)Solution (B) and (C) will follow Raoult’s law.
(ii)Solution (A) will follow Raoult’s law.
(iii)Solution (B) will show negative deviation from Raoult’s law.
(iv)Solution (C) will show positive deviation from Raoult’s law.

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(ii) Solution (A) will follow Raoult’s law.

Q22Multiple choice

Two beakers of capacity 500 mL were taken. One of these beakers, labelled as “A”, was filled with 400 mL water whereas the beaker labelled “B” was filled with 400 mL of 2 M solution of NaCl. At the same temperature both the beakers were placed in closed containers of same material and same Fig. 2.2 capacity as shown in Fig. 2.2. At a given temperature, which of the following statement is correct about the vapour pressure of pure water and that of NaCl solution.

This question refers to a figure in the original PDF.

(i)vapour pressure in container (A) is more than that in container (B).
(ii)vapour pressure in container (A) is less than that in container (B).
(iii)vapour pressure is equal in both the containers.
(iv)vapour pressure in container (B) is twice the vapour pressure in container (A).

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(i) vapour pressure in container (A) is more than that in container (B).

Q23Multiple choice

If two liquids A and B form minimum boiling azeotrope at some specific composition then _______________.

(i)A–B interactions are stronger than those between A–A or B–B.
(ii)vapour pressure of solution increases because more number of molecules of liquids A and B can escape from the solution.
(iii)vapour pressure of solution decreases because less number of molecules of only one of the liquids escape from the solution.
(iv)A–B interactions are weaker than those between A–A or B–B.

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(i) A–B interactions are stronger than those between A–A or B–B.

Q24Multiple choice

4L of 0.02 M aqueous solution of NaCl was diluted by adding one litre of water. The molality of the resultant solution is _____________.

(i)0.004 21 Solutions
(ii)0.008
(iii)0.012
(iv)0.016

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(iv) 0.016

Q25Multiple choice

On the basis of information given below mark the correct option. Information : On adding acetone to methanol some of the hydrogen bonds between methanol molecules break.

(i)At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult’s law.
(ii)At specific composition methanol-acetone mixture forms maximum boiling azeotrope and will show positive deviation from Raoult’s law.
(iii)At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show negative deviation from Raoult’s law.
(iv)At specific composition methanol-acetone mixture will form maximum boiling azeotrope and will show negative deviation from Raoult’s law.

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(ii) At specific composition methanol-acetone mixture forms maximum boiling azeotrope and will show positive deviation from Raoult’s law.

Q26Multiple choice

KH value for Ar(g), CO2(g), HCHO (g) and CH4(g) are 40.39, 1.67, 1.83×10–5 and 0.413 respectively. Arrange these gases in the order of their increasing solubility.

(i)HCHO < CH4 < CO2 < Ar
(ii)HCHO < CO2 < CH4 < Ar
(iii)Ar < CO2 < CH4 < HCHO
(iv)Ar < CH4 < CO2 < HCHO

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(iii) Ar < CO2 < CH4 < HCHO

Q27Multiple correct

Which of the following factor (s) affect the solubility of a gaseous solute in the fixed volume of liquid solvent? (a) nature of solute (b) temperature (c) pressure

(i)(a) and (c) at constant T
(ii)(a) and (b) at constant P
(iii)(b) and (c) only
(iv)(c) only

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(i) (a) and (c) at constant T

(ii) (a) and (b) at constant P

Q28Multiple correct

Intermolecular forces between two benzene molecules are nearly of same strength as those between two toluene molecules. For a mixture of benzene and toluene, which of the following are not true?

(i)∆mix H = zero
(ii)∆mix V = zero
(iii)These will form minimum boiling azeotrope.
(iv)These will not form ideal solution.

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(iii) These will form minimum boiling azeotrope.

(iv) These will not form ideal solution.

Q29Multiple correct

Relative lowering of vapour pressure is a colligative property because _____________.

(i)It depends on the concentration of a non electrolyte solute in solution and does not depend on the nature of the solute molecules.
(ii)It depends on number of particles of electrolyte solute in solution and does not depend on the nature of the solute particles.
(iii)It depends on the concentration of a non electrolyte solute in solution as well as on the nature of the solute molecules.
(iv)It depends on the concentration of an electrolyte or nonelectrolyte solute in solution as well as on the nature of solute molecules.

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(i) It depends on the concentration of a non electrolyte solute in solution and does not depend on the nature of the solute molecules.

(ii) It depends on number of particles of electrolyte solute in solution and does not depend on the nature of the solute particles.

Q30Multiple correct

Van’t Hoff factor i is given by the expression _____________. Normal molar mass

(i)i= Abnormal molar mass Abnormal molar mass
(ii)i= Normal molar mass Observed colligative property
(iii)i= Calculated colligative property Calculated colligative property
(iv)i= Observed colligative property

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(i) i= Abnormal molar mass Abnormal molar mass

(iii) i= Calculated colligative property Calculated colligative property

Q31Multiple correct

Isotonic solutions must have the same _____________.

(i)solute
(ii)density
(iii)elevation in boiling point
(iv)depression in freezing point

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(ii) density

(iii) elevation in boiling point

Q32Multiple correct

Which of the following binary mixtures will have same composition in liquid and vapour phase?

(i)Benzene - Toluene
(ii)Water-Nitric acid
(iii)Water-Ethanol
(iv)n-Hexane - n-Heptane

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(ii) Water-Nitric acid

(iii) Water-Ethanol

Q33Multiple correct

In isotonic solutions ________________.

(i)solute and solvent both are same. 23 Solutions
(ii)osmotic pressure is same.
(iii)solute and solvent may or may not be same.
(iv)solute is always same solvent may be different.

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(ii) osmotic pressure is same.

(iii) solute and solvent may or may not be same.

Q34Multiple correct

For a binary ideal liquid solution, the variation in total vapour pressure versus composition of solution is given by which of the curves?

(i)
(ii)
(iii)
(iv)

Show answer

(i)

(iv)

Q35Multiple correct

Colligative properties are observed when _____________.

(i)a non volatile solid is dissolved in a volatile liquid.
(ii)a non volatile liquid is dissolved in another volatile liquid.
(iii)a gas is dissolved in non volatile liquid.
(iv)a volatile liquid is dissolved in another volatile liquid.

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(i) a non volatile solid is dissolved in a volatile liquid.

(ii) a non volatile liquid is dissolved in another volatile liquid.

Q36Short answer

Components of a binary mixture of two liquids A and B were being separated by distillation. After some time separation of components stopped and composition of vapour phase became same as that of liquid phase. Both the components started coming in the distillate. Explain why this happened.

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Since both the components are appearing in the distillate and composition of liquid and vapour is same, this shows that liquids have formed azeotropic mixture and hence cannot be separated at this stage by distillation.

Q37Short answer

Explain why on addition of 1 mol of NaCl to 1 litre of water, the boiling point of water increases, while addition of 1 mol of methyl alcohol to one litre of water decreases its boiling point.

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NaCl is a non volatile solute, therefore, addition of NaCl to water lowers the vapour pressure of water. As a result boiling point of water increases. Methyl alcohol on the other hand is more volatile than water, therefore its addition increases, the total vapour pressure over the solution and a decrease in boiling point of water results.

Q38Short answer

Explain the solubility rule “like dissolves like” in terms of intermolecular forces that exist in solutions.

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A substance (solute) dissolves in a solvent if intermolecular interactions are similar in both the components; for example, polar solutes dissolve in polar solvents and non polar solutes in non polar solvents thus we can say “like dissolves like”.

Q39Short answer

Concentration terms such as mass percentage, ppm, mole fraction and molality are independent of temperature, however molarity is a function of temperature. Explain.

Show answer

Molarity of a solution is defined as the number of moles of solute dissolved in one litre of solution. Since volume depends on temperature and undergoes a change with change in temperature, the molarity will also change with change in temperature. On the other hand, mass does not change with change in temperature, as a result other concentration terms given in the question remain unchanged by changing temperature. According to the definition of all these terms, mass of the solvent used for making the solution is related to the mass of solute.

Q40Short answer

What is the significance of Henry’s Law constant KH?

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Higher the value of Henry’s law constant KH, the lower is the solubility of the gas in the liquid.

Q41Short answer

Why are aquatic species more comfortable in cold water in comparison to warm water?

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At a given pressure the solubility of oxygen in water increases with decrease in temperature. Presence of more oxygen at lower temperature makes the aquatic species more comfortable in cold water. 29 Solutions

Q42Multiple choice

(a) Explain the following phenomena with the help of Henry’s law.

(i)Painful condition known as bends.
(ii)Feeling of weakness and discomfort in breathing at high altitude. (b) Why soda water bottle kept at room temperature fizzes on opening?

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Refer to the NCERT textbook for Class XII.

Q43Short answer

Why is the vapour pressure of an aqueous solution of glucose lower than that of water?

Show answer

In pure liquid water the entire surface of liquid is occupied by the molecules of water. When a non volatile solute, for example glucose is dissolved in water, the fraction of surface covered by the solvent molecules gets reduced because some positions are occupied by glucose molecules. As a result number of solvent molecules escaping from the surface also gets reduced, consequently the vapour pressure of aqueous solution of glucose is reduced.

Q44Short answer

How does sprinkling of salt help in clearing the snow covered roads in hilly areas? Explain the phenomenon involved in the process.

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When salt is spread over snow covered roads, snow starts melting from the surface because of the depression in freezing point of water and it helps in clearing the roads.

Q45Short answer

What is “semi permeable membrane”?

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Continuous sheets or films (natural or synthetic) which contain a network of submicroscopic holes or pores through which small solvent molecules like water can pass; but the passage of bigger molecules of solute is hindered, are known as semi permeable membrane.

Q46Short answer

Give an example of a material used for making semipermeable membrane for carrying out reverse osmosis.

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Cellulose acetate. IV. Matching Type

Q47Multiple choice

Match the items given in Column I and Column II. Column I Column II (i) Saturated solution

(a)Solution having same osmotic pressure at a given temperature as that of given solution. (ii) Binary solution
(b)A solution whose osmotic pressure is less than that of another. (iii) Isotonic solution
(c)Solution with two components. (iv) Hypotonic solution
(d)A solution which contains maximum amount of solute that can be dissolved in a given amount of solvent at a given temperature. (v) Solid solution (e) A solution whose osmotic pressure is more than that of another. (vi) Hypertonic solution (f) A solution in solid phase. 25 Solutions

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(a) Solution having same osmotic pressure at a given temperature as that of given solution. (ii) Binary solution

(d) A solution which contains maximum amount of solute that can be dissolved in a given amount of solvent at a given temperature. (v) Solid solution (e) A solution whose osmotic pressure is more than that of another. (vi) Hypertonic solution (f) A solution in solid phase. 25 Solutions

(b) A solution whose osmotic pressure is less than that of another. (iii) Isotonic solution

Q48Multiple choice

Match the items given in Column I with the type of solutions given in Column II. Column I Column II (i) Soda water

(a)A solution of gas in solid (ii) Sugar solution
(b)A solution of gas in gas (iii) German silver
(c)A solution of solid in liquid (iv) Air
(d)A solution of solid in solid (v) Hydrogen gas in palladium (e) A solution of gas in liquid (f) A solution of liquid in solid

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(a) A solution of gas in solid (ii) Sugar solution

(b) A solution of gas in gas (iii) German silver

(d) A solution of solid in solid (v) Hydrogen gas in palladium (e) A solution of gas in liquid (f) A solution of liquid in solid

Q49Multiple choice

Match the laws given in Column I with expresions given in Column II. Column I Column II (i) Raoult’s law

(a)∆Tf = Kfm (ii) Henry’s law
(b)Π = CRT o o (iii) Elevation of boiling point
(c)p = x1p1 + x2p2 (iv) Depression in freezing point
(d)∆Tb = Kbm (v) Osmotic pressure (e) p = KH.x

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(a) ∆Tf = Kfm (ii) Henry’s law

(b) Π = CRT o o (iii) Elevation of boiling point

(d) ∆Tb = Kbm (v) Osmotic pressure (e) p = KH.x

Q50Multiple choice

Match the terms given in Column I with expressions given in Column II. Column I Column II Number of moles of the (i) Mass percentage

(a)solute component Volume of solution in litres Number of moles of a component (ii) Volume percentage
(b)Total number of moles of all the components Volume of the solute component (iii) Mole fraction
(c)in solution × 100 Total volume of solution Mass of the solute component (iv) Molality
(d)in solution × 100 Total mass of the solution Number of moles of the solute components (v) Molarity (e) Mass of solvent in kilograms

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(a) solute component Volume of solution in litres Number of moles of a component (ii) Volume percentage

(d) in solution × 100 Total mass of the solution Number of moles of the solute components (v) Molarity (e) Mass of solvent in kilograms

(b) Total number of moles of all the components Volume of the solute component (iii) Mole fraction