JEE Chemistry Solutions MCQs Set C

Question. The freezing point of equimolal aqueous solutions will be highest for
(a) C₆H₁₂O₆ (glucose)
(b) La(NO₃)₃
(c) Ca(NO₃)₂
(d) None of these

Answer: A

Question. At 25°C, the highest osmotic pressure is exhibited by 0.1 M solution of
(a) CaCl₂
(b) glucose
(c) KCl
(d) urea

Answer: A

Question. Which one of the following salts will have the same value of van’t Hoff factor (i) as that of K₄[Fe(CN)₆].
(a) Al₂(SO₄)₃
(b) NaCl
(c) Na₂SO₄
(d) None of these

Answer: A

Question. Which of the following 0.10 m aqueous solutions will have the lowest freezing point ?
(a) Al₂(SO₄)₃
(b) C₆H₁₂O₆
(c) KCl
(d) None of these

Answer: A

Question. Study the given statements and choose the correct option. (i) 3.62 mass percentage of sodium hypochlorite in water is used as commercial bleaching solution.
(ii) 35% volume percentage of ethylene glycol is used as an antifreeze (as coolent in car engines).
(iii) Concentration of dissolved oxygen in a litre of sea water is 5.8 ppm
(a) Statements (i),(ii) and (iii) are correct
(b) Statements (ii) and (iii) are correct
(c) Statements (i) and (iii) are correct
(d) Statements (i) and (ii) are correct

Answer: A

Question. Molarity and molality of a solution of NaOH is calculated. If now temperature of the solution is increased then which of the following statement(s) is/are correct ? (i) Molarity of solution decreases
(ii) Molality of the solution increases
(a) Statement (i) is correct only
(b) Statement (ii) is correct only
(c) Both statements are incorrect
(d) Both statements are correct

Answer: A

Question. “If temperature increases solubility of gas decreases”. For this situation which of the following statement(s) is/are correct ? (i) Reaction is endothermic
(ii) Le-chatelier’s principle can be applied
(a) Statement (ii) is correct only
(b) Both statement(s) (i) and (ii) are incorrect
(c) Statement (i) is correct only
(d) Statement (i) and (ii) both are correct

Answer: A

Question. Read the following statements and choose the correct option. (i) Polar solutes dissolve in a polar solvent.
(ii) Polar solutes dissolve in a non-polar solvent.
(iii) Non-polar solutes dissolve in a non-polar solvent.
(iv) Non-polar solutes dissolve in a polar solvent
(a) (i) and (iii) are correct
(b) (ii) and (iv) are correct.
(c) (i), (ii) and (iii) are correct.
(d) (i) and (ii) are correct.

Answer: A

Question. Read the following statements carefully and choose the correct option (i) The vapour pressure of a liquid decreases with increase of temperature.
(ii) The liquid boils at the temperature at which its vapour pressure is equal to the atmospheric pressure.
(iii) Vapour pressure of the solvent decreases in the presence of non-volatile solute.
(iv) Vapour pressure of the pure solvent and solution is a function of temperature.
(a) (ii), (iii), and (iv) are correct
(b) (i), (ii) and (iii) are correct
(c) (i), (iii), and (iv) are correct
(d) (i), (ii) and (iv) are correct

Answer: A

Question. On the basis of information given below mark the correct option. (i) In bromoethane and chloroethane mixture intermolecular interactions of A-A and B-B type are nearly same as A-B type interactions.
(ii) In ethanol and acetone mixture A-A or B-B type intermolecular interactions are stronger than A-B type interactions.
(iii) In chloroform and acetone mixture A-A or B-B type intermolecular interactions are weaker than A-B type interactions.
(a) Solution (i) will follow Raoult's law
(b) Solution (ii) and (iii) will follow Raoult's law
(c) Solution (ii) will show negative deviation from Raoult's law.
(d) Solution (iii) will show positive deviation from Raoult's law

Answer: A

Question. Which observation(s) reflect(s) colligative properties? (i) A 0.5 m NaBr solution has a higher vapour pressure than a 0.5 m BaCl₂ solution at the same temperature
(ii) Pure water freezes at the higher temperature than pure methanol
(iii) a 0.1 m NaOH solution freezes at a lower temperature than pure water
Choose the correct answer from the codes given below
(a) (i) and (iii)
(b) (i) and (ii)
(c) (i), (ii) and (iii)
(d) (ii) and (iii)

Answer: A

Question. Read the following statements carefully and choose the correct option (i) Osmotic pressure is not a colligative property.
(ii) For dilute solutions, osmotic pressure is proportional to the molarity, C of the solution at a given temperature T.
(iii) During osmosis ,solvent molecules always flow from higher concentration to lower concentration of solution.
(iv) The osmotic pressure has been found to depend on the concentration of the solution
(a) (ii) and (iv) are correct
(b) (i), (ii) and (iv) are correct
(c) (iii), and (iv) are correct
(d) (i), (ii) and (iii) are correct

Answer: A

Question. Assertion : Molarity of a solution in liquid state changes with temperature.
Reason : The volume of a solution changes with change in temperature
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question. Assertion : If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., p_s > p^o.
Reason : In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.
(a) Assertion is correct, reason is incorrect
(b) Assertion is incorrect, reason is correct
(c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: A

Question. Assertion : Azeotropic mixtures are formed only by non-ideal solutions and they may have boiling points either greater than both the components or less than both the components.
Reason : The composition of the vapour phase is same as that of the liquid phase of an azeotropic mixture
(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question. Assertion : If one component of a solution obeys Raoult’s law over a certain range of composition, the other component will not obey Henry’s law in that range.
Reason : Raoult’s law is a special case of Henry’s law
(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question. Assertion : When methyl alcohol is added to water, boiling point of water increases.
Reason : When a volatile solute is added to a volatile solvent elevation in boiling point is observed
(a) Assertion is incorrect, reason is correct
(b) Assertion is correct, reason is incorrect
(c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: A

Question. Assertion : When NaCl is added to water a depression in freezing point is observed.
Reason : The lowering of vapour pressure of a solution causes depression in the freezing point
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question. Assertion : When a solution is separated from the pure solvent by a semi- permeable membrane, the solvent molecules pass through it from pure solvent side to the solution side
Reason : Diffusion of solvent occurs from a region of high concentration solution to a region of low concentration solution.
(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(b) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question. The normality of orthophosphoric acid having purity of 70 % by weight and specific gravity 1.54 is
(a) 33 N
(b) 11 N
(c) 22 N
(d) 44 N

Answer: A

Question. Which one of the following gases has the lowest value of Henry’s law constant?
(a) CO₂
(b) He
(c) N₂
(d) H₂

Answer: A

Question. Equal masses of methane and oxygen are mixed in an empty container at 25°C. The fraction of the total pressure exerted by oxygen is
(a) 1/3
(b) 2/3
(c) 1/2
(d) None of these

Answer: A

Question. When a gas is bubbled through water at 298 K, a very dilute solution of the gas is obtained. Henry’s law constant for the gas at 298 K is 100 kbar. If the gas exerts a partial pressure of 1 bar, the number of millimoles of the gas dissolved in one litre of water is
(a) 0.555
(b) 5.55
(c) 0.0555
(d) 55.5

Answer: A

Question. What is the ratio of no. of moles of nitrogen to that of oxygen in a container of 5 litre at atmospheric pressure?
(a) 1 : 1.71
(b) 2 : 1
(c) 1 : 2
(d) 1 : 24

Answer: A

Question. Consider a and b are two components of a liquid mixture, their corresponding vapour pressure (mmHg) are respectively 450 and 700 in pure states and total pressure given is 600. Then corresponding composition in liquid phase will be
(a) 0.4, 0.6
(b) 0.6, 0.4
(c) 0.5, 0.5
(d) 0.3, 0.7

Answer: A

Question. Which will form maximum boiling point azeotrope
(a) HNO₃ + H₂O solution
(b) C₂H₅OH + H₂O solution
(c) Both
(d) None of these

Answer: A

Question. 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
(c) 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

Answer: A

Question. Chloroform and acetone are added to each other, Raoult’s law shows negative deviation.what does this suggests ?
(a) Exothermic reaction
(b) Endothermic reaction
(c) Zero change in enthalpy
(d) None of these

Answer: A

Question. At 300 K the vapour pressure of an ideal solution containing 1 mole of liquid A and 2 moles of liquid B is 500 mm of Hg. The vapour pressure of the solution increases by 25 mm of Hg, if one more mole of B is added to the above ideal solution at 300 K. Then the vapour pressure of A in its pure state is
(a) 300 mm of Hg
(b) 500 mm of Hg
(c) 400 mm of Hg
(d) 600 mm of Hg

Answer: A

Question. Someone has added a non electrolyte solid to the pure liquid but forgot that among which of the two beakers he has added that solid. This problem can be solved by checking
(a) all above
(b) depression in Freezing point
(c) elevation in boiling point
(d) relative lower in vapour pressure

Answer: A

Question. The vapour pressure of a solvent decreases by 10 mm of Hg when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of Hg ?
(a) 0.6
(b) 0.2
(c) 0.8
(d) 0.4

Answer: A

Question. Vapour pressure of benzene at 30°C is 121.8 mm. When 15g of a non-volatile solute is dissolved in 250 g of benzene, its vapour pressure is decreased to 120.2 mm. The molecular weight of the solute is
(a) 356.7 g
(b) 356.7 g
(c) 35.67 g
(d) 432.8 g

Answer: B

Question. For a dilute solution containing 2.5 g of a non-volatile nonelectrolyte solute in 100 g of water, the elevation in boiling point at 1 atm pressure is 2°C. Assuming concentration of solute is much lower than the concentration of solvent, the vapour pressure (mm of Hg) of the solution is (take K_b = 0.76 K kg mol^–1)
(a) 724
(b) 740
(c) 736
(d) 718

Answer: A

Question. 1 g of a non-volatile, non-electrolyte solute of molar mass 250 g/mol was dissolved in 51.2 g of benzene. If the freezing point depression constant K_f of benzene is 5.12 kg K mol^–1. The freezing point of benzene is lowered by
(a) 0.4 K
(b) 0.5 K
(c) 0.3 K
(d) 0.2 K

Answer: A

Question. The boiling point of 0.2 mol kg^–1 solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case ?
(a) X is undergoing dissociation in water
(b) Y is undergoing dissociation in water while X undergoes no change
(c) Molecular mass of X is less than the molecular mass of Y.
(d) Molecular mass of X is greater than the molecular mass of Y.

Answer: A

Question. What is the freezing point of a solution containing 8.1 g HBr in 100 g water assuming the acid to be 90% ionised ? (K_f for water = 1.86 K kg mol^–1)
(a) – 3.53°K
(b) – 0.35°K
(c) 0.85°K
(d) 0°K

Answer: A

Question. An 1% solution of KCl (I), NaCl (II), BaCl₂ (III) and urea (IV) have their osmotic pressure at the same temperature in the ascending order (molar masses of NaCl, KCl, BaCl₂ and urea are respectively 58.5, 74.5, 208.4 and 60 g mole_–1). Assume 100% ionization of the electrolytes at this temperature
(a) III < IV < I < II
(b) III < I < II < IV
(c) I < III < II < IV
(d) I < II < III < IV

Answer: A