JEE Main Previous Year Papers Questions With Solutions Chemistry Solutions and Colligative Properties

JEE Main Previous Year Papers Questions With Solutions Chemistry Solutions and Colligative Properties

1.Freezing point of an aqueous solution is (- 0.186)°C Elevation of boiling point of the same solution is Kb= 0.512°C, Kr = 1.86°C, And the increase in boiling point. (2002)
1)186°C               2)    0.0512°C
3) 0.092°C          4)     0.2372°C

2.With increase of temperature, which of these changes ?  (2002)
1) molality
2) weight fraction of solution
3) fraction of solute present in water
4) mole fraction

Ans.(3)Volume increases with rise in temperature
4.If liquids A and B form an ideal solution
1)the enthalpy of mixing is zero (2003)
2)the free energy of mixing is zero
3)the free energy as well as the entropy of mixing are each zero
4)the enthalpy of mixing is zero

5.25ml of a solution of barium hydroxide on titration with a 0.1 molar solution of hydrochloric acid gave a litre value of 35 ml. The molarity of barium hydroxide solution was        (2003)
1)14 2) 0.28             3) 0.35              4) 0.07

6.A pressure cooker reduces cooking time for food because  (2003)
1)boiling point of water involved in cooking is increased
2)the higher pressure inside the cooker crushes the food material
3)cooking involves chemical changes helped by a rise in temperature
4)heat is more evently distributed in the cooking space

Ans.(1) On increasing pressure, the temperature is also increased. Thus in pressure cooker due to increase in pressure the b.p. of water increases.
7.Which one of the following aqueous solutions will exhibit highest boiling point ?         (2004)
1)01 M Na2S04                    2) 0.015 M glucose
3) 0.015 M urea                    4) 0.01 M KN03

8.To neutralize completely 20 mL of 0.1 M aqueous solution of phosphorous acid (H3P03), the volume of 0.1 M aqueous KOH solution required is      (2004)
1)10 mL                      2) 60 mL
3) 40 mL                    4) 20 mL

9.For which of the following parameters the structural isomers C2II5OH and CH3OCH3 would be expected to have the same values? (assume ideal behaviour)      (2004)
1)Heat of vaporization
2)Gaseous densities at the same temperature and pressure
3)Boiling points
4)Vapour pressure at the same temperature

Ans.(2) The molecular weight of C2H5OH and CH3OCH3 are same. So in its vapour phase at same temperature and pressure, the densities of both the substances will be same.
10.Which of the following liquid pairs shows a positive deviation from Raoult’s law? (2004)
1)Water – hydrochloric acid
2)Acetone – chloroform
3)Water – nitric acid
4) Benzene-methanol

Ans.(4) Benzene in methanol breaks the hydrogen bonding of the alcohol making its boiling point decrease and there by its vapour pressure increases leading two +ve deviation.
Ans.(2) Dependency on concentration as well as nature of solute.
13.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 partial vapour pressure of benzene at 20°C for a solution containing 78 g of benzene and 46 g of toluene in torr is (2005)
1)50   2)25        3)37.5    4)53.5
14.Two solutions of a substance (non-electrolyte) are mixed in the following manner. 480 ml of 1.5 M first solution + 520 mL of 1.2 M second solution. What is the molarity of the final mixture ?     (2005)
1) 1.20 M                       2) 1.50 M
3) 1.344 M                      4) 2.70 M

Ans.(3) The molarity of the mixture is in between those of the solutions mixed.
15. Equimolar solutions in the same solvent have (2005)
1)Same boiling point but different freezing point
2)Same freezing point but different boiling point
3)Same boiling and same freezing points
4)Different boiling and different freezing points

Ans.(3) Same properties of boiling and freezing
16.18 g of glucose (C6H1206) is added to 178.2 g of water. The vapour pressure of water for this aqueous solution at 100°C is (2006)
1) 759.00 Torr   2) 7.60 Torr
3) 76.00 Torr      4) 752.40 Torr

17.Density of a 2.05 M solution of acetic acid in water is 1.02 g/mL. The molality of the solution is (2006)
1) 1.14     mol kg-1                2)     3.28 mol kg-1
3) 2.28      mol kg-1                4)      0.44 mol kg-1

Ans.(3) One litre solution has 2.05 mol of solute and 960g of solvent.
18.A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60g mol-1) in the same solvent. If the densities of both the solutions are assumed to be equal to l.Og cm-3, molar mass of the substance will be        (2007)
1) 90.0     g mol-1                   2)     115.0 g mol-1
3) 105.0 g mol-1                     4)     210.0 g mol-1

19.The density (in g mL-1) of a 3.60 M sulphuric acid solution that is 29% H2SQ4 (Molar mass = 98 g mol-1) by mass will be            (2007)
1) 1.64           2) 1.88             3) 1.22            4) 1.45

20.A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm at 300 K. The vapour pressure of propyl alcohol is 200 mm. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure (in mm) at the same temperature will be    (2007)
1)350             2)300               3)700              4)360

21.At 80°C, the vapour pressure of pure liquid ‘A’ is 520 mm Hg and that of pure liquid ‘B’ is 1000 mm Hg. If a mixture solution of ‘A’ and ‘B’ boils at 80°C‘and 1 atm pressure, the amount of ‘A’ in the mixture is (1 atm = 760 mm Hg)      (2008)
1) 52 mol percent           2) 34 mol percent
3) 48 mol percent           4) 50 mol percent

22.The vapour pressure of water at 20°C is 17.5 mm Hg. If 18 g of glucose (C6H12Os) is added to 178.2g of water at 20°C, the vapour pressure of the resulting solution will be (2008)
1) 17.675 mm Hg    2)         15.750 mm Hg
3) 16.500 mm Hg             4)  17.325 mm Hg

23.Two liquids X and Y form an ideal solution. At 300 K, vapour pressure of the solution containing 1 mol of X and 3 mol of Y is 550 mm Hg. At the same temperature, if 1 mol of Y is further added to this solution, vapour pressure of the solution increases by 10 mm Hg. Vapour pressure (in mm Hg) of X and Y in their pure states will be, respectively(2009)
1) 200 and 300                2)  300 and 400
3) 400 and 600                4)  500 and 600

24.A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution ?    (2009)
1)The solution formed is an ideal solution
2)The solution is non-ideal, showing +ve deviation from Raoult’s law.
3)The solution is non-ideal, showing -ve deviation from R aoult’s law.
4)n-Heptane shows +ve deviation while ethanol show -ve deviation from Raoult’s law

Ans.(2) The interactions between n-heptane and  ethanol are weaker than that in pure components.
26.On mixing, heptane and octane form an ideal solution. At 373 K, the vaopur pressure of the two liquid components (heptane and octane) are 105 kPa and 45 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0g of heptane and 35g of octane will be (molar mass of heptane = lOOg mol-1 and of octane = 114 g mol-1).   (2010)
1) 72.0 kPa          2)   36.1  kPa
3) 96.2 kPa        4) 144.5    kPa

27.A 5.2 molal aqueous solution of methyl alcohol, m CH3OH, is supplied. What is the mole fraction !; of methyl alcohol in the solution ?    (2011)
1) 0.086                         2)   0.050
3) 0.100                         4)   0.190

28.Ethylene glycol is used as an antifreeze in a cold climate. Mass of ethylene glycol which should be added to 4 kg of water to prevent it from freezing at – 6°C will be : (Kf for water = 1.86 K kg mol-1, and molar mass of ethylene glycol = 62 g mol-1)     (2011)
1) 400.0 g                      2) 304.60 g
3) 804.32 g                     4) 204.30 g

30.The density of a solution prepared by „ dissolving 120g of urea (mol. mass = 60u) in j; 1000 g water is 1.15 g/mL. The molarity of this solution is     (2012)
1) 0.50 M                                2) 1.78 M
3)1.02 M                                4) 2.05 M

31.Kf for water is 1.86 K kg mol-1. If your automobile radiator holds 1.0 kg of water, how many grams fo ethylene glycol (C2H602) must you add to get the freezing point of the solution lowered to -2.8°C ?       (2012)
1) 72 g 2) 93 g 3) 39 g 4) 27 g

32.The molarity of a solution obtained by mixing 750mL of 0.5(M) HC/ with 250 mL of 2(M) HO will be   (2013)
1) 0.875 M                     2) 1.00 M
3) 1.75M                        4) 0.975 M

33.Consider separate solutions of 0.500 M C2H5OH(aq), 0.100M Mg3(P04)2(aq), 0.250M KBr(aq) and 0.125M Na3P04(aq) at 25°C. Which statement is true about these solutions, assuming all salts to be strong electrolytes ?(2014)
1)500M C2H5OH(aq) has the highest osmotic pressure
2)They all have the same osmotic pressure
3)100 M M3(P04)2(aq) has the highest osmotic pressure
4) 0.125M Na3P04(aq) has the highest osmotic pressure

34.The vapour pressure of acetone at 20° is 185 torn When 1.2 g of a non-volatile substance was dissolved in 100 g of acetone at 20°C, its vapour pressure was 183 torn The molar mass (g mo/-1) of the substance is       (2015)
1) 32           2) 64           3) 128         4) 488


Courtesy : CBSE