JEE Main & Advanced Chemistry Solutions / विलयन Question Bank

done Lowering of vapour pressure Total Questions - 44

• question_answer1)
  Vapour pressure of \[CC{{l}_{4}}\] at \[{{25}^{o}}C\] is \[143mm\] of \[Hg\,0.5\,gm\] of a non-volatile solute (mol. wt. = 65) is dissolved in \[100\,ml\,CC{{l}_{4}}\]. Find the vapour pressure of the solution (Density of \[CC{{l}_{4}}=1.58\,g/c{{m}^{2}}\])     [CBSE PMT 1998]
  A)
                  \[141.43\,mm\]      done clear
  B)
                  \[94.39\,mm\] done clear
  C)
                  \[199.34\,mm\]      done clear
  D)
                  \[143.99\,mm\] done clear
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• question_answer2)
  For a solution of volatile liquids the partial vapour pressure of each component in solution is directly proportional to
  A)
                  Molarity  done clear
  B)
                  Mole fraction done clear
  C)
                  Molality  done clear
  D)
                  Normality done clear
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• question_answer3)
  ?The relative lowering of the vapour pressure is equal to the mole fraction of the solute.? This law is called [MP PET 1997, 2001]
  A)
                  Henry's law            done clear
  B)
                  Raoult's law done clear
  C)
                  Ostwald's law         done clear
  D)
                  Arrhenius's law done clear
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• question_answer4)
  The relative lowering of vapour pressure produced by dissolving 71.5 g of a substance in 1000 g of water is 0.00713. The molecular weight of the substance will be [DPMT 2001]
  A)
                  18.0 done clear
  B)
                  342 done clear
  C)
                  60           done clear
  D)
              180 done clear
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• question_answer5)
  When mercuric iodide is added to the aqueous solution of potassium iodide, the      [IIT 1987]
  A)
                  Freezing point is raised done clear
  B)
              Freezing point is lowered done clear
  C)
                  Freezing point does not change done clear
  D)
                  Boiling point does not change done clear
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• question_answer6)
  Vapour pressure of a solution is [EAMCET 1988; MP PET 1994]
  A)
                  Directly proportional to the mole fraction of the solvent done clear
  B)
                  Inversely proportional to the mole fraction of the solute done clear
  C)
                  Inversely proportional to the mole fraction of the solvent done clear
  D)
                  Directly proportional to the mole fraction of the solute done clear
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• question_answer7)
  When a substance is dissolved in a solvent the vapour pressure of the solvent is decreased. This results in [NCERT 1981]
  A)
                  An increase in the b.p. of the solution done clear
  B)
                  A decrease in the b.p. of the solvent done clear
  C)
                  The solution having a higher freezing point than the solvent done clear
  D)
                  The solution having a lower osmotic pressure than the solvent done clear
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• question_answer8)
  If \[{{P}^{o}}\] and \[P\] are the vapour pressure of a solvent and its solution respectively  and \[{{N}_{1}}\] and \[{{N}_{2}}\] are the mole fractions of the solvent and solute respectively, then correct relation is
  A)
                  \[P={{P}^{o}}{{N}_{1}}\]              done clear
  B)
                  \[P={{P}^{o}}{{N}_{2}}\] done clear
  C)
                  \[{{P}^{o}}=P\,{{N}_{2}}\]            done clear
  D)
                  \[P={{P}^{o}}\,({{N}_{1}}/{{N}_{2}})\] done clear
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• question_answer9)
  An aqueous solution of methanol in water has vapour pressure                                    [MNR 1986]
  A)
                  Equal to that of water done clear
  B)
                  Equal to that of methanol done clear
  C)
                  More than that of water done clear
  D)
                  Less than that of water done clear
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• question_answer10)
  The pressure under which liquid and vapour can coexist at equilibrium is called the
  A)
                  Limiting vapour pressure                     done clear
  B)
              Real vapour pressure done clear
  C)
                  Normal vapour pressure done clear
  D)
                  Saturated vapour pressure done clear
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• question_answer11)
  Which solution will show the maximum vapour  pressure at 300 K                                              [DPMT 2001]
  A)
              1 M \[C{{}_{12}}{{H}_{22}}{{O}_{11}}\]   done clear
  B)
                  1 M \[C{{H}_{3}}COOH\] done clear
  C)
                  1 M \[NaC{{l}_{2}}\]           done clear
  D)
                  1 M \[NaCl\] done clear
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• question_answer12)
  The relative lowering of the vapour pressure is equal to the ratio between the number of [EAMCET 1991; CBSE PMT 1991]
  A)
                  Solute moleules and solvent molecules done clear
  B)
                  Solute molecules and the total molecules in the solution done clear
  C)
                  Solvent molecules and the total molecules in the solution done clear
  D)
                  Solvent molecules and the total number of ions of the solute done clear
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• question_answer13)
  \[5c{{m}^{3}}\] of acetone is added to \[100\,c{{m}^{3}}\] of water, the vapour pressure of water over the solution
  A)
                  It will be equal to the vapour pressure of pure water done clear
  B)
                  It will be less than the vapour pressure of pure water done clear
  C)
                  It will be greater than the vapour pressure of pure water done clear
  D)
                  It will be very large done clear
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• question_answer14)
  At 300 K, when a solute is added to a solvent its vapour pressure over the mercury reduces from 50 mm to 45 mm. The value of mole fraction of solute will be
  A)
                  0.005      done clear
  B)
                  0.010 done clear
  C)
                  0.100      done clear
  D)
                  0.900 done clear
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• question_answer15)
  A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressure of the pure hydrocarbons at 20°C are 440 mmHg for pentane and 120 mmHg for hexane. The mole fraction of pentane in the vapour phase would be [CBSE PMT 2005]
  A)
                  0.549      done clear
  B)
                  0.200 done clear
  C)
                  0.786      done clear
  D)
                  0.478 done clear
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• question_answer16)
  Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The parial vapour pressure of benzene at 20°C for a solution containing 78g of benzene and 46g of toluene in torr is           [AIEEE 2005]
  A)
                  50           done clear
  B)
                  25 done clear
  C)
                  37.5        done clear
  D)
                  53.5 done clear
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• question_answer17)
  The vapour pressure lowering caused by the addition of 100 g  of sucrose(molecular mass = 342) to 1000 g of water if the vapour pressure of pure water at \[{{25}^{o}}C\] is 23.8 mm Hg [RPET 1999]
  A)
                  1.25 mm Hg          done clear
  B)
                  0.125 mm Hg done clear
  C)
                  1.15 mm Hg          done clear
  D)
                  00.12 mm Hg done clear
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• question_answer18)
  Which of the following is incorrect      [J & K 2005]
  A)
                  Relative lowering of vapour pressure is independent done clear
  B)
                  The vapour pressure is a colligative property done clear
  C)
              Vapour pressure of a solution is lower than the vapour pressure of the solvent done clear
  D)
                  The relative lowering of vapour pressure is directly propertional to the original pressure done clear
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• question_answer19)
  Among the following substances the lowest vapour pressure is exerted by
  A)
                  Water      done clear
  B)
                  Mercury done clear
  C)
                  Kerosene                done clear
  D)
                  Rectified spirit done clear
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• question_answer20)
  According to Raoult's law the relative lowering of vapour pressure of a solution of volatile substance is equal to [CBSE PMT 1995; BHU 2001]
  A)
                  Mole fraction of the solvent done clear
  B)
                  Mole fraction of the solute done clear
  C)
                  Weight percentage of a solute done clear
  D)
                  Weight percentage of a solvent done clear
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• question_answer21)
  When a substance is dissolved in a solvent, the vapour pressure of the solvent is decreased. This results in [MP PMT 1983; NCERT 1981]
  A)
                  An increase in the boiling point of the solution done clear
  B)
                  A decrease in the boiling point of solvent done clear
  C)
                  The solution having a higher freezing point than the solvent done clear
  D)
                  The solution having a lower osmotic pressure than the solvent done clear
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• question_answer22)
  The vapour pressure of a liquid depends on
  A)
                  Temperature but not on volume done clear
  B)
                  Volume but not on temperature done clear
  C)
                  Temperature and volume done clear
  D)
                  Neither on temperature nor on volume done clear
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• question_answer23)
  Which one of the statements given below concerning properties of solutions, describes a colligative effect              [AIIMS 2003]
  A)
                  Boiling point of pure water decreases by the addition of ethanol done clear
  B)
                  Vapour pressure of pure water decreases by the addition of nitric acid done clear
  C)
                  Vapour pressure of pure benzene decreases by the addition of naphthalene done clear
  D)
                  Boiling point of pure benzene increases by the addition of toluene done clear
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• question_answer24)
  The atmospheric pressure is sum of the [Kerala CET (Med.) 2002]
  A)
                  Pressure of the biomolecules done clear
  B)
                  Vapour pressure of atmospheric constituents done clear
  C)
                  Vapour pressure of chemicals and vapour pressure of volatiles done clear
  D)
                  Pressure created on to atmospheric molecules done clear
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• question_answer25)
  The vapour pressure of pure liquid A is 0.80 atm. On mixing a non-volatile B to A, its vapour pressure becomes 0.6 atm. The mole fraction of B in the solution is        [MP PET 2003]
  A)
                  0.150      done clear
  B)
              0.25 done clear
  C)
                  0.50        done clear
  D)
                  0.75 done clear
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• question_answer26)
  Lowering of vapour pressure is highest for        [BHU 1997]
  A)
                  Urea        done clear
  B)
                  \[0.1M\] glucose done clear
  C)
                  \[0.1\,M\,MgS{{O}_{4}}\]   done clear
  D)
              \[0.1\,M\,BaC{{l}_{2}}\] done clear
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• question_answer27)
  An aqueous solution of glucose was prepared by dissolving 18 g of glucose in 90 g of water. The relative lowering in vapour pressure is                 [KCET 2002]
  A)
              0.02        done clear
  B)
                  1 done clear
  C)
                  20           done clear
  D)
                  180 done clear
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• question_answer28)
  ?Relative lowering in vapour pressure of solution containing non-volatile solute is directly proportional to mole fraction of solute?. Above statement is            [AFMC 2004]
  A)
                  Henry law              done clear
  B)
                  Dulong and Petit law done clear
  C)
                  Raoult's law           done clear
  D)
              Le-Chatelier's principle done clear
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• question_answer29)
  An ideal solution was obtained by mixing methanol and ethanol. If the partial vapour pressure of methanol and ethanol are \[2.619\,kPa\] and \[4.556\,kPa\] respectively, the composition of the vapour (in terms of mole fraction) will be     [Pb. PMT 1998]
  A)
                  0.635 methanol, 0.365 ethanol done clear
  B)
                  0.365 methanol, 0.635 ethanol done clear
  C)
                  0.574 methanol, 0.326 ethanol done clear
  D)
                  0.173 methanol, 0.827 ethanol done clear
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• question_answer30)
  The vapour pressure of two liquids P and Q are 80 and 600 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mole of Q would be [CBSE PMT 2005]
  A)
                  140 torr  done clear
  B)
                  20 torr done clear
  C)
                  68 torr    done clear
  D)
                  72 torr done clear
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• question_answer31)
  The vapour pressure of benzene at a certain temperature is \[640\,mm\] of \[Hg\]. A non-volatile and non-electrolyte solid weighing \[2.175g\] is added to \[39.08g\] of benzene. The vapour pressure of the solution is \[600mm\] of \[Hg\]. What is the molecular weight of solid substance [CBSE PMT 1999; AFMC 1999]
  A)
                  49.50      done clear
  B)
                  59.6 done clear
  C)
                  69.5        done clear
  D)
                  79.8 done clear
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• question_answer32)
  Which one of the following is the expression of Raoult's law
  A)
  \[\frac{p-{{p}_{s}}}{p}=\frac{n}{n+N}\]       done clear
  B)
  \[\frac{{{p}_{s}}-p}{p}=\frac{N}{N+n}\] done clear
  C)
  \[\frac{p-{{p}_{s}}}{{{p}_{s}}}=\frac{N}{N-n}\]         done clear
  D)
   \[\frac{{{p}_{s}}-p}{{{p}_{s}}}=\frac{N-n}{N}\]          done clear
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• question_answer33)
  Which has maximum vapour pressure               [DPMT 2001]
  A)
                  HI            done clear
  B)
                  HBr done clear
  C)
                  HCl         done clear
  D)
                  HF done clear
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• question_answer34)
  When a non-volatile solute is dissolved in a solvent, the relative lowering of vapour pressure is equal to [BHU 1979; IIT 1983]
  A)
                  Mole fraction of solute done clear
  B)
                  Mole fraction of solvent done clear
  C)
                  Concentration of the solute in grams per litre done clear
  D)
                  Concentration of the solute in grams 100 \[ml\] done clear
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• question_answer35)
  60 gm of Urea (Mol. wt 60) was dissolved in 9.9 moles, of water. If the vapour pressure of pure water is \[{{P}_{o}}\], the vapour pressure of solution is                      [DCE 2000]
  A)
                  0.10 \[{{P}_{o}}\]                done clear
  B)
                  1.10 \[{{P}_{o}}\] done clear
  C)
                  0.90 \[{{P}_{o}}\]                done clear
  D)
                  0.99 \[{{P}_{o}}\] done clear
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• question_answer36)
  The vapour pressure of water at \[{{20}^{o}}C\] is 17.54 mm. When 20g of a non-ionic, substance is dissolved in 100g of water, the vapour pressure is lowered by 0.30 mm. What is the molecular weight of the substances       [UPSEAT 2001]
  A)
                  210.2      done clear
  B)
                  206.88 done clear
  C)
                  215.2      done clear
  D)
                  200.8 done clear
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• question_answer37)
  In an experiment, 1 g of a non-volatile solute was dissolved in 100 g of acetone (mol. mass = 58) at 298K. The vapour pressure of the solution was found to be 192.5 mm Hg. The molecular weight of the solute is (vapour pressure of acetone = 195 mm Hg) [CPMT 2001; CBSE PMT 2001; Pb CET 2002]
  A)
                  25.24      done clear
  B)
                  35.24 done clear
  C)
                  45.24      done clear
  D)
                  55.24 done clear
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• question_answer38)
  How many grams of \[C{{H}_{3}}OH\] should be added to water to prepare \[150\,ml\] solution of \[2\,M\,C{{H}_{3}}OH\]          [CBSE PMT 1994]
  A)
                  9.6          done clear
  B)
                  2.4 done clear
  C)
                  \[9.6\times {{10}^{3}}\]    done clear
  D)
                  \[2.4\times {{10}^{3}}\] done clear
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• question_answer39)
  The vapour pressure of a solvent decreased by \[10mm\] of mercury, 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 decrease in the vapour pressure is to be \[20\,mm\] of mercury [CBSE PMT 1998]
  A)
                  0.8          done clear
  B)
              0.6 done clear
  C)
                  0.4          done clear
  D)
                  0.2 done clear
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• question_answer40)
  For a dilute solution, Raoult's law states that [CPMT 1987; BHU 1979; IIT 1985; MP PMT 2004; MNR 1988; AMU 2002]
  A)
                  The lowering of vapour pressure is equal to mole fraction of solute done clear
  B)
                  The relative lowering of vapour pressure is equal to mole fraction of solute done clear
  C)
                  The relative lowering of vapour pressure is proportional to the amount of solute in solution done clear
  D)
                  The vapour pressure of the solution is equal to the mole fraction of solvent done clear
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• question_answer41)
  The vapour pressure of a solvent A is 0.80 atm  When a non-volatile substance B is added to this solvent its vapour pressure drops to 0.6 atm. What is mole fraction of B in solution                                 [MP PMT 2000, 01]
  A)
                  0.25        done clear
  B)
                  0.50 done clear
  C)
                  0.75        done clear
  D)
                  0.90 done clear
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• question_answer42)
  Determination of correct molecular mass from Raoult's law is applicable to
  A)
                  An electrolyte in solution done clear
  B)
              A non-electrolyte in a dilute solution done clear
  C)
                  A non-electrolyte in a concentrated solution done clear
  D)
                  An electrolyte in a liquid solvent done clear
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• question_answer43)
  If two substances \[A\] and \[B\] have \[P_{A}^{0}:\,P_{B}^{0}=1\,:\,2\] and have mole fraction in solution 1 : 2 then mole fraction of \[A\] in vapours                                  [DPMT 2005]
  A)
                  0.33        done clear
  B)
              0.25 done clear
  C)
                  0.52        done clear
  D)
                  0.2 done clear
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• question_answer44)
  A dry air is passed through the solution, containing the 10 gm of solute and 90 gm of water and then it pass through pure water. There is the depression in weight of solution wt by 2.5 gm and in weight of pure solvent by 0.05 gm. Calculate the molecular weight of solute    [Kerala CET 2005]
  A)
                  50           done clear
  B)
              180 done clear
  C)
                  100         done clear
  D)
                  25 done clear
  E)
                  51 done clear
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