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m=) ocala, , SOLUTIONS, , , , > Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids,, solid solutions, Raoult’s law, colligative properties - relative lowering of vapour pressure, elevation of, boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using, colligative properties., , STAND ALONE MCQs [1 Mark each], , , , , , Q. 1. A molar solution is one that contains one mole of a . | ;, solute in Explanation: An increase in temperature increase, , (A) 1000 g of the solvent the volume of solution and therefore it will result, , (B) one litre of the solvent Inatpanclanty todecrese,, , (©) one litre of the solution Q.4. Ky value for Ar(g), CO2(g), HCHO(g) and CHy(g), (D) 22.4 litre of the solution A are 4.039, 1.67, 1.83 x 10°, and 0.143, respectively., Ans. Option (C) is correct. Arrange these gases in the order of their increasing, solubili, Explanation: A molar sokationis one that contains (A) eee < CI < CO) < Ar, one mole of a solute in one litre of the solution. (B) HCHO < CO) < CH, < Ar, iNianiter of melew-of.ech (C) Ar < CO, < CH, < HCHO, Molarity (3a) umeer of moles ob solute (D) Ar < CHy < CO) < HCHO Al, ‘Volume of solution in L Ans. Option (C) is correct., Q.2. In which mode of expression, the concentration of Explanation: According to Henry’s law,, a solution remains independent of temperature? P=KyC, (A) Molarity (B) Normality 1, (©) Formality (D) Molality a eee, Ans. Option (D) is correct. Where P = Partial pressure of gas, Explanation: The molality of a solution does not C= Concentration of gas, , Ky = Henry’s constant, , change with temperature. oo a, It implies that as the value of Ky increases, mole, , Q. 3. The increase in the temperature of the aqueous fraction of gas solute in solvent decreases., solution will result in its en higher the Ky value, lower is the, solubility of gas., (a) Molar fy kosngreae ‘The order of increasing solubility of gases in :, (B) Molarity to decrease Ar < CO, < CH, < HCHO, , (C) Mole fraction to increase Q. 5. A beaker contains a solution of substance ‘W., , (D) Mass % to increase [Al Precipitation of substance ‘ takes place when, Ans. Option (B) is correct. small amount of ‘Nis added to the solution. The, solution is P

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(A) saturated, (©) unsaturated, Ans. Option (B) is correct., , Explanation: When a small amount of solute is, added to its solution, it does not dissolve and get, precipitated then this type of solution is called as, supersaturated solution., , (B) supersaturated, (D) concentrated, , Q. 6. At equilibrium the rate of dissolution of a solid, solute in a volatile liquid solvent is, (A) less than the rate of crystallisation, (B) greater than the rate of crystallisation, (C) equal to the rate of crystallisation, (D) zero, Ans. Option (C) is correct., , , , Explanation: In equilibrium state the rate of, dissolution of a solid solute in a volatile liquid, solvent is equal to the rate of crystallization., , , , .7. Which of the following aqueous solutions should, have the highest boiling point?, (A) LOM NaOH (B) 10M Na,SOq, (C) 1.0 MNH4NO3 (D) 10MKNO,, , Ans. Option (B) is correct., , Explanation: 1.0 M NagSQq since it furnishes, maximum number of ions (2Na* + S04”)., , , , Q.8. When 1 mole of benzene is mixed with 1 mole of, toluene the vapour will contain : (Given : vapour of, benzene = 12.8kPa and vapour pressure of toluene, = 3.85 kPa). CBSE, SQP, 2020-2021], (A) equal amount of benzene and toluene as it, , forms an ideal solution, (B) unequal amount of benzene and toluene as it, forms a non ideal solution, (©) higher percentage of benzene, (D) higher percentage of toluene, Ans. Option (C) is correct., , , , Explanation: When 1 mole of benzene is mixed, with 1 mole of toluene the vapour will contain, higher percentage of benzene. As it is an ideal, solution, it follows Raoult’s law., The vapour pressure of the solution depends on, the mole fraction of the solvent., , a oe, , Pin is the vapour pressure of the solution, , is the mole fraction of the solvent, , Peivent 8 the Vapour pressure of the pure solvent, Since the mole fraction of both the components, is same, but the vapour pressure of benzene is, higher than the toluene, its percentage will be, greater in the vapour of the solution., , Q.9. If two liquids A and B form minimum boiling, azeotrope at some specific composition then, , (A) A-B interactions are stronger than those, between A-A or B-B., , (B) Vapour pressure of solution increases because, more number of molecules of liquids A and B, can escape from the solution., , (©) Vapour pressure of solution decreases because, less number of molecules of only one of the, liquids escape from the solution., , (D) A-B interactions are weaker than those, between A-A or B-B. R, , ‘Ans. Option (D) is correct., , , , Explanation: When solute-solvent. or AB, , interactions are weaker than the A-A or B-B, , interactions, molecules of A or B will find it easier, , to escape than in pure state. This will increase, , the vapour pressure and result in positive, , deviation from Raoult’s law. Such solutions are, , called minimum boiling azeotropes., , (BD) Q. 10. For a dilute solution, Raoult’s law states that, , (A) The lowering of vapour pressure is equal to the, mole fraction of solute., , (B) The relative lowering of vapour pressure is, equal to the mole fraction of solute., , (©) The relative lowering of vapour pressure, is proportional to the amount of solute in, , , , solution., (D) The vapour pressure of the solution is equal to, the mole fraction of the solute. iR, , Ans. Option (B) is correct., , Explanation: According to Raoult’s law, for a, dilute solution, the relative lowering of vapour, pressure is equal to the mole fraction of solute., , Relative lowering of vapour pressure, , , , Kye, , mole fraction of solute, , (Al) O. 11. Which of the following units is useful in relating, , concentration of solution with its vapour pressure?, (A) Mole fraction (B) Parts per million, , (C) Masspercentage — (D) Molality, , Ans. Option (A) is correct., Explanation: Mole fraction is used in relating, vapour pressure with concentration of solution, and according to the Raoult’s law, the partial, vapour pressure of each component in the, solution is directly proportional to its mole, fraction., Q. 12. The unit of ebullioscopic constant is :, (A) Kkg mol! or K (molalityy!, (B) mol kg! KT or K! (molality), (C) kg mol K# or Kt (molality?, (D) K mol kg™ or K (molality), Ans. Option (A) is correct., Explanation: Itis the unit of ebullioscopic constant, (kK), k = K kg mol" or K (molality)

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. 13. Value of Henry’s constant is . 16. Consider the figure and mark the correct option., Value of Henry’ Kui Consider the figure and mark th pti, (A) Increases with increase in temperature. Piston (A) Piston (B), , (B) Decreases with increase in temperature on A |, , , , , , , , , , , , , , (C) Remains constant, 2 ie aifiensd Concentrated], (D) First increases then decreases. Presh water sodium, Ans. Option (A) is correct. (a) anode, Explanation: Value of Henry's constant increases waiter (B), with increase in temperature. (A) Water will move from side (A) to side (B), (BD Q. 14. Considering the formation, breaking and strength ee eae oxmohe presiite ta, of hydrogen bond, predict which of the following (B) Water will move from side (B) to side (A) if, mixtures will show a positive deviation from pressure greater than osmotic pressure is, Raoult’s law? applied on piston (B). :, (A) Methanolandacetone. (©) Water will move from side (B) to side (A) if, pressure equal to osmotic pressure is applied, (B) Chloroformand acetone. on piston @)., (C) Nitricacid and water (D) Water will move from side (A) to side (B) if, (D) Phenolandaniline. Dreseure a to osmotic pressure is applied, on piston (A)., , Ans. Option (A) is correct. AvieOptian (B) 18 erect,, , Explanation: Mixture of methanol and acetone Frplanation: Water will move from side (R), , exhibits positive deviation because methanol- casas (A) (a presse premier than oemiotie, methanol and acetone-acetone interaction is pressure is applied on piston (B). This is a process, more than methanol-acetone. The more number of reverse osmosis., of hydrogen bonds are broken the less number Q. 17. Which of the following solutions in water has, of new hydrogen bonds are formed. highest boiling point?, , (A) 1MNacl (B) IMMgcl,, , Q.15. If two liquids A and B form minimum boiling, azeotrope at some specific composition, then., , (A) A-B interactions are stronger than those, , between A-Aor B-B. Explanation: 1 M MgCl, in aqueous solution, , (B) vapour pressure of solution increases gives maximum number of ions than other, solutions. So, it has highest boiling, point., , (C) [Murea (C) 1 Mglucose, Ans. Option (B) is correct., , because more number of molecules ofliquids, ‘Aand B can escape from the solution. Q. 18. Relative lowering of vapour pressure is a colligative, property because, , (© vapour pressure of solution decreases (A) It depends on number of particles of electrolyte, , because less number of molecules of only solute in solution and does not depend on the, one of the liquids escape from the solution. nature of the solute particles,, (D) A-Binteractions are weaker than those between (B) It depends on the concentration of a non, electrolyte solute in solution as well as on the, , Schon eB nature of the solute molecules., Ans. Option (A) is correct. (C) Is depends on the concentration of an, : | oo. electrolyte or non-electrolyte solute is solution, Explanation: If A-B interactions is less than as well on the nature of solute molecules., A-A or B-B the vapour pressure will be more (D) None of the above, and the result will be positive deviation. The Ans. Option (A) is correct., solutions which exhibits positive deviation form Engle Cilligitee property doparilic om, minimum boiling azeotropes. the number of solute particles and not on the, , nature of the particles., , ASSERTION AND REASON BASED MCQs over, , , , , , Directions: In the following questions, A statement (C) Ais true but R is false, of Assertion (A) is followed by a statement of (D) Ais false and R is ‘True, Reason (R). Mark the correct choice as. Q.1, Assertion (A):, (A) Both Aand Rare true and Ris the correct explanation, of A, (B) Both A and R are true but R is NOT the correct, explanation of A, , A molar solution is more, concentrated than molal solution., Reason (R): A molar solution contains one mole of, solute in 1000 mL of solution., , Ans. Option (A) is correct.

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Explanation: A molar solution is more, concentrated than molal sokution because 1, molar solution contains 1 mole of solute in 1 litre, of the solution which include both solute and, solvent., , Q.2. Assertion (A): Molarity of 0.1 N solution of HCl is, 01M., , Reason (R): Normality and molarity of a solution, are always equal., Ans. Option (C) is correct., Explanation: Normality and molarity of a solution, are not always equal. Normality depends on, chemical equivalent of the substance while, molarity depends on molecular mass of the, substance., Q. 3. Assertion (A): Molarity of a solution changes, with temperature., Reason (R): Molarity is dependent on volume of, solution., Ans. Option (A) is correct., , , , Explanation: As molarity is dependent on volume, of solution and volume rises with increase in, temperature. Molarity is inversely proportional, to temperature. So, as temperature increases,, volume increases and molarity decreases., |. Assertion (A): Molarity of a solution in liquid state, changes with temperature., Reason (R): ‘he volume of a solution changes with, change in temperature., Ans. Option (A) is correct., Explanation: Molarity changes with temperature, because volume changes with temperature,, , Q. 5. Assertion (A): An ideal solution obeys Henry’s law., Reason (R): In an ideal solution, solute-solute as well, as solvent-solvent interactions are similar to solutesolvent interaction. [CBSE Delhi Set-IIL, 2020], , Ans. Option (D) is correct., , , , CASE-BASED MCQs, , , , , , I. Read the passage given below and answer the, following questions :, , Scuba apparatus includes a tank of compressed, air toted by the diver on his or her back, a hose, for carrying air to a mouthpiece, a face mask that, covers the eyes and nose, regulators that control, air flow, and gauges that indicate depth and how, much air remains in the tank., , A diver who stays down too long, swims too deep,, or comes up too fast can end up with a condition, called “the bends.” In this case, bubbles of gas in, the blood can cause intense pain, even death., , , , a An ideal solution obeys axle, law., , Q. 6. Assertion (A): Dimethyl ether is less volatile than, ethyl alcohol., Reason (R): Dimethyl ether has greater vapour, pressure than ethyl alcohol., , Ans. Option (D) is correct., , [ae Dimethyl ether is more wea, than ethyl alcohol., Q. 7. Assertion (A): Vapour pressure increase with, increase in temperature., Reason (R): With increase in temperature, more, ‘molecules of the liquid can go into vapour phase., Ans. Option (A) is correct., , Explanation: Vapour pressure increase with, increase in temperature because more molecules, of the liquid can go into vapour phase with, increase in temperature., , Q. 8. Assertion (A): Elevation in boiling point is a, colligative property., Reason (R): Elevation in boiling point is directly, proportional to molarity. [CBSE Delhi Set-I, II 2020], Ans. Option (A) is correct., , Explanation: Elevation in boiling point is a, colligative property. It is directly proportional to, molarity., , AT, =K, xm, , Q.9%. Assertion (A): 0.1 M solution of KCl has great, osmotic pressure than 0.1 M solution of glucose at, same temperature., , Reason (R): In solution KCI dissociates to produce, more number of particles., [CBSE Delhi Set 2, 2020], , Ans. Option (A) is correct., , Explanation: KCl is ionic compound, hence, dissociates into ions bul glucose is a covalent, compound which does not dissociate into ions., , , , In these following questions a statement of, , assertion followed by a statement of reason, , is given. Choose the correct answer out of the, following choices., , (A) Assertion and Reason both are correct, statements and Reason is correct explanation, for Assertion., , (B) Assertion and Reason both are, statements but Reason is not, explanation for Assertion., , correct, correct, , (C) Assertion is correct statement but Reason is, wrong statement., , (D) Assertion is wrong, statement but Reason is, correct statement.

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Q.1. Assertion : Scuba divers may face a medical, condition called ‘bends’, Reason : ‘Bends’ can be explained with the help of, Henry's law ap it links Uhe partial pressure of gas lo, that of its mole fraction., , Ans. Option (A) is correct,, , Explanation: Henry’s law explains some biological, phenomena like the ‘bends’ experienced by the, scuba divers. Since mole fraction of a gas in the, solution is a measure of its solubility., , Q. 2. Assertion : Bends is caused due to formation of, , nitrogen bubbles in the blood of scuba divers, which blocks the capillaries., Reason : Underwater high pressure increases, solubility of gases in blood, while as pressure, gradually decreases moving towards the surface,, gases are released and nitrogen bubbles are formed, in blood., , Ans. Option (A) is correct., , Explanation: Scuba divers must cope with, high concentrations of dissolved gases while, breathing air at high pressure underwater., Increased pressure increases the solubility of, atmospheric gases in blood. When the divers, come towards surface, the pressure gradually, decreases. This releases the dissolved gases and, leads to the formation of bubbles of nitrogen in, the blood. This blocks capillaries and creates a, medical condition known as bends, , (AI) O. 3. Assertion : Soft drinks and soda water bottles are, , sealed under high pressure., Reason : High pressure maintains the taste and, texture of the soft drinks., , Ans. Option (C) is correct., , Explanation: The bottle is sealed under high, pressure to increase the solubility of CO, in soft, drinks and soda water, , Q.4. Assertion : Anoxia is a condition experienced by, climbers which makes them suddenly agile and, unable to think clearly., , Reason : At high altitudes the partial pressure of, oxygen is less than that at the ground level., , Ans. Option (D) is correct., , Explanation: At high altitudes the partial, pressure of oxygen is less than that at the ground, level. This leads to low concentrations of oxygen, in the blood and tissues of people living at high, altitudes or climbers. This leads to a condition, called anoxia caused due to low oxygen in blood,, making the climbers to become weak and unable, to think clearly., , , , OR, Assertion : Solubility of gases in liquids decreases, with rise in temperature., , Reason : As dissolution is an exothermic process,, the solubility should decrease with increase of, temperature., , Ans. Option (A) is correct,, , , , Explanation: Solubility of gases in liquids, decreases with rise in temperature. As dissolution, is an exothermic process, the solubility should, decrease with increase of temperature., , I. Read the passage given below and answer the, following questions :, Raoult’s law states that for a solution of volatile, liquids, the partial vapour pressure of each, component of the solution is directly proportional, to its mole fraction present in solution. Dalton’s, law of partial pressure states that the total, pressure (Protat) Over the solution phase in the, container will be the sum of the partial pressures, of the components of the solution and is given as :, Protat = Py +P, , Vapour pressure, of solution, , , , Vapour pressure, , , , , , K,=0 Mole fraction. =1, Kt i, on, , Q.1. What type of deviation from Raoult’s law does the, above graph represent ?, (A) Hist positive then negative, (B) Negative deviation, (©) Positive deviation, (D) First negative then positive, Ans. Option (B) is correct., | Explanation: Negative deviation l, , Q. 2. In comparison to a 0.01 M solution of glucose, the, depression in freezing point of a 0.01 M MgCl,, solution is :, , (A) thesame, (B) about twice, (© about three limes, (D) aboutsix times, Ans. Option (C) is correct., Explanation: AT, =iKjm, where i=1 for glucose., cose, AT = 1x Kx 0.01, In case of MgCl, > Mg?* + 2Cl-, where i = 3,, OT = 3 x O01 x Ky, , = IME = 3 x are, , Hence, the depression in freezing point of MgCh,, is three times that of glucose.