CBSE Class 12 Chemistry Solutions MCQs Set 07

Question. The vapour pressure at a given temperature of an ideal solution containing 0.2 mol of a non-volatile solute and 0.8 mol of solvent is 60 mm of Hg. The vapour pressure of the pure solvent at the same temperature is
(a) 150 mm of Hg
(b) 60 mm of Hg
(c) 75 mm of Hg
(d) 120 mm of Hg

Answer  : C

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) C₁₂H₂₂O₁₁ 

Answer  : A

Question. During osmosis, flow of water through a semipermeable membrane is
(a) from both sides of semipermeable membrane with equal flow rates
(b) from both sides of semipermeable membrane with unequal flow rates
(c) from solution having lower concentration only
(d) from solution having higher concentration only

Answer  : C

Question. For an electrolyte, elevation of B.P. is directly proportional to
(a) molarity
(b) molality
(c) mole fraction
(d) All of these

Answer  : B

Question. Which of the following is dependent on temperature?
(a) Molarity
(b) Mole fraction
(c) Weight percentage
(d) Molality

Answer  : A

Question. What is the mole fraction of the solute in a 1.00 m aqueous solution?
(a) 1.770
(b) 0.0354
(c) 0.0177
(d) 0.177

Answer  : C

Question. How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M HNO₃? The concentrated acid is 70% HNO₃.
(a) 70.0 g conc. HNO₃
(b) 54.0 g conc. HNO₃
(c) 45.0 g conc. HNO₃
(d) 90.0 g conc. HNO₃

Answer  : C

Question. Which of the following compounds can be used as antifreeze in automobile radiators?
(a) Methyl alcohol
(b) Glycol
(c) Nitrophenol
(d) Ethyl alcohol

Answer  : B

Question. Concentrated aqueous sulphuric acid is 98% H₂SO₄ by mass and has a density of 1.80 g mL–1. Volume of acid required to make one litre of 0.1 M H₂SO₄ solution is
(a) 16.65 mL
(b) 22.20 mL
(c) 5.55 mL
(d) 11.10 mL

Answer  : C

Question. The mole fraction of the solute in one molal aqueous solution is
(a) 0.009
(b) 0.018
(c) 0.027
(d) 0.036

Answer  : B

Question. 2.5 litre of 1 M NaOH solution is mixed with another 3 litre of 0.5 M NaOH solution. Then find out molarity of resultant solution.
(a) 0.80 M
(b) 1.0 M
(c) 0.73 M
(d) 0.50 M

Answer  : C

Question. How many g of dibasic acid (mol. weight 200) should be present in 100 mL of the aqueous solution to give strength of 0.1 N?
(a) 10 g
(b) 2 g
(c) 1 g
(d) 20 g

Answer  : C

Question. What is the molarity of H2SO4 solution, that has a density 1.84 g/cc at 35°C and contains 98% by weight?
(a) 18.4 M
(b) 18 M
(c) 4.18 M
(d) 8.14 M

Answer  : A

Question. The mixture which shows positive deviation from Raoult’s law is
(a) ethanol + acetone
(b) benzene + toluene
(c) acetone + chloroform
(d) chloroethane + bromoethane.

Answer  : A

Question. For an ideal solution, the correct option is
(a) DmixG = 0 at constant T and P
(b) DmixS = 0 at constant T and P
(c) Dmix V ≠ 0 at constant T and P
(d) Dmix H = 0 at constant T and P.

Answer  : D

Question. The mixture that forms maximum boiling azeotrope is
(a) heptane + octane
(b) water + nitric acid
(c) ethanol + water
(d) acetone + carbon disulphide.

Answer  : B

Question. Which of the following statements is correct regarding a solution of two components A and B exhibiting positive deviation from ideal behaviour?
(a) Intermolecular attractive forces between A-A and B-B are stronger than those between A-B.
(b) Δmix H = 0 at constant T and P.
(c) Δmix V = 0 at constant T and P.
(d) Intermolecular attractive forces between A-A and B-B are equal to those between A-B.

Answer  : A

Question. Which one of the following is incorrect for ideal solution?
(a) DHmix = 0
(b) DUmix = 0
(c) DP = Pobs – Pcalculated by Raoult’s law = 0
(d) DGmix = 0

Answer  : D

Question. Which of the following statements about the composition of the vapour over an ideal 1 : 1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at 25°C.
(Given, vapour pressure data at 25°C, benzene = 12.8 kPa, toluene = 3.85 kPa)
(a) The vapour will contain equal amounts of benzene and toluene.
(b) Not enough information is given to make a prediction.
(c) The vapour will contain a higher percentage of benzene.
(d) The vapour will contain a higher percentage of toluene.

Answer  : C

Question. The concentration unit, independent of temperature, would be
(a) normality
(b) weight volume percent
(c) molality
(d) molarity.

Answer  : C

Question. How many grams of CH³OH should be added to water to prepare 150 mL solution of 2 M CH³OH?
(a) 9.6 × 10³
(b) 2.4 × 10³
(c) 9.6
(d) 2.4

Answer  : C

Question. In water saturated air, the mole fraction of water vapour is 0.02. If the total pressure of the saturated air is 1.2 atm, the partial pressure of dry air is
(a) 1.18 atm
(b) 1.76 atm
(c) 1.176 atm
(d) 0.98 atm.

Answer  : C

Question. pA and pB are the vapour pressures of pure liquid components, A and B, respectively of an ideal binary solution. If xA represents the mole fraction of component A, the total pressure of the solution will be
(a) pA + xA(pB – pA)
(b) pA + xA ( pA – pB)
(c) pB + xA(pB – pA)
(d) pB + xA ( pA – pB)

Answer  : D

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

Answer  : D

Question. The vapour pressure of two liquids P and Q are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mol of Q would be
(a) 72 torr
(b) 140 torr
(c) 68 torr
(d) 20 torr

Answer  : A

Question. The osmotic pressure of 0.2 molar solution ofw·ea at 27°C (R = 0.082L atrn mol^-1 K^-1) is 
(a) 4.92 atm
(b) 1 atrn
(c) 0.2 atm
(d) 27 atrn

Answer  : A

Question. Dry air is passed through a solution containing 10 g of a solute in 90 g of water and then through pure water. The loss in weight of solution is 2.5 g and that of pure solvent is 0.05 g. Calculate the molecular weight of the solute.
(a) 50
(b) 180
(c) 102
(d) 25

Answer  : C

Question. Calculate the molal depression constant of a solvent which has freezing point 16.6°C and latent heat of fusion 180.75 Jg^-1 · 
(a) 2.68
(b) 3.86
(c) 4.68
(d) 2.86

Answer  : B

Question. In an osmotic pressure measurement experiment, a 5% solution of compound’ X’ is found to be isotonic with a 2% acetic acid solution. The gram molecular mass of X’ is
(a) 24
(b) 60
(c) 150
(d) 300

Answer  : C

Question. By dissolving 5 g substance in 50 g of water, the decrease in freezing point is 1.2°C. The gram molal depression is 1.85°C. The molecular weight of substance is
(a) 105.4
(b) 118.2
(c) 137.2
(d) 154.2

Answer  : D

Question. The volume of water to be added to 100cm3 of 0.5 N H₂SO₄ to get decinormal concentration is 
(a) 400cm³
(b) 450cm³
(c) 500cm³
(d) 100cm³

Answer  : A

Question. The vapour pressure of water at 23 °C is 19.8 mm. 0.1 mole of glucose is dissolved in 178.2 g of water. What is the vapour pressure (in mm) of the resultant solution ?
(a) 19.0
(b) 19.602
(c) 19.402
(d) 19.202

Answer  : B

Question. van’t Hoff factor of Ca(NO₃)₂ is 
(a) one
(b) two
(c) three
(d) four

Answer  : C

Question. van ‘t Hoff factor more than unity indicates that the solute in solution has
(a) dissociated
(b) associated
(c) Both (a) and (b)
(d) cannot say anything

Answer  : A