Solutions PYQs Set 3 (PDF)

Set 3 of 12 · Questions 61-90 of 332

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Mere Teacher · Previous Year Questions NEET Chemistry · Solutions · Set 3 (Q61-90)
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61. $What is the weight (in gram) of Na_{2} CO_{3} (molarmass = 106) present in 250 mL of its 0.2 M solution?$ (1) $0.53$ (2) $5.3$ (3) $1.06$ (4) $10.6$ 62. $Calculate the depression in freezing point of solution when 4 g non-volatile solute of molar mass 126 g mol^{- 1} dissolved in 80 mL water. [Cryoscopic constant of water = 1.86 K kg mol^{- 1}]$ (1) $0.55 K$ (2) $0.74 K$ (3) $0.86 K$ (4) $0.98 K$ 63. $' x' g of NaCl is added to water in a beaker with a lid. The temperature of the system is raised from 1^{\circ} C to 25^{\circ} C . Which out of the following plots, is best suited for the change in the molarity (M) of the solution with respect to temperature? [Consider the solubility of NaCl remains unchanged over the temperature range]$ (1) (2) (3) (4) 64. $The experimental depression in freezing point of a dilute solution is 0.025 K . If the van't Hoff factor (i) is 2.0 , the calculated depression in freezing point (in K) is$ (1) $0.00125$ (2) $0.025$ (3) $0.0125$ (4) $0.05$ 65. $The concentration unit, independent of temperature, would be$ (1) $normality$ (2) $weight volume percent$ (3) $molality$ (4) $molarity$ 66. $The measured osmotic pressure of a solution prepared by dissolving 17.4 mg of K_{2} SO_{4} in 2 L of water at 27^{\circ} C is 3.735 \times 10^{- 3} bar. The van't Hoff factor is (R = 0.083 L) bar K^{- 1} mol^{- 1}; atomic weights K = 39, S = 32; O = 16)$ (1) $2.84$ (2) $3.0$ (3) $2.0$ (4) $2.32$ 67. $of nitrogen gas dissolves in of water at and one atm pressure due to nitrogen gas. The mole fraction of nitrogen in of water at nitrogen pressure is approximately$ (1) $1 \times 10^{- 6}$ (2) $1 \times 10^{- 5}$ (3) $1 \times 10^{- 3}$ (4) $1 \times 10^{- 4}$ 68. $Dissolving 120 g of a compound (mol. wt = 60) in 1000 g of water gave a solution of density 1.12 g mL^{- 1} . The molarity of solution is$ (1) $1.0 M$ (2) $2.0 M$ (3) $2.5 M$ (4) $4.0 M$ 69. $An aqueous dilute solution containing non-volatile solute boils at 100.52^{\circ} C . What is the molality of solution? (K_{b} = 0.52 kg mol^{- 1} K), boiling temperature of water = (100^{\circ} C)$ (1) $0.1 m$ (2) $0.01 m$ (3) $0.001 m$ (4) $1.0 m$ 70. $1.00 g of a non‐electrolyte solute (molar mass 250 g m o l^{- 1}) was dissolved in 51.2 g ofbenzene. If the freezing point depression constant, K_{f} of benzene is 5.12 K kg m o 1^{- 1}, the freezing point of benzene will be lowered by$ (1) $0.2 K$ (2) $0.4 K$ (3) $0.3 K$ (4) $0.5 K$ 71. $' x^{’} g of urea (molar mass 60 g mol^{- 1}) is completely dissolved in ' y' g of pure water and the solution boiled at 373.202 K . If the boiling point of pure water at 1.013 bar is 373.15 K, then x : y is (K_{b} (H_{2} O) = 0.52 K kg mol^{- 1})$ (1) $6.0 \times 10^{- 3}$ (2) $3.0 \times 10^{- 3}$ (3) $9.0 \times 10^{- 3}$ (4) $4.5 \times 10^{- 3}$ 72. $The relation between solubility of a gas in liquid at constant temperature and external pressure is stated by which law?$ (1) $Raoult's law$ (2) $van't Hoff Boyle's law$ (3) $van't Hoff Charles' law$ (4) $Henry's law$ 73. $The Van’t Hoff factor (i) for a dilute aqueous solution of the strong electrolyte barium hydroxide is$ (1) $0$ (2) $1$ (3) $2$ (4) $3$ 74. $Given below are two statements : Statement (I): NaCl is added to the ice at 0^{\circ} C, present in the ice cream box to prevent the melting of ice cream. Statement (II): On addition of NaCl to ice at 0^{\circ} C, there is a depression in freezing point. choose the correct answer from the options given below :$ (1) $Both Statement I and Statement II are false$ (2) $Statement I is false but Statement II is true$ (3) $Statement I is true but Statement II is false$ (4) $Both Statement I and Statement II are true$ 75. $The freezing point (in ºC) of a solution containing 0.1 g of K_{3} [Fe (C N)_{6}] (Mol. Wt. 329) in 100 g of water (K_{f} = 1.86 K kg m o l^{-1}) is :$ (1) $- 2.3 \times 1 0^{-2}$ (2) $- 5.7 \times 1 0^{-2}$ (3) $- 5.7 \times 1 0^{-3}$ (4) $- 1.2 \times 1 0^{-2}$ 76. $Which of the following does not belong to an ideal solution?$ (1) $Δ H_{mix} = 0$ (2) $Δ V_{mix} = 0$ (3) $Obeys Raoult's law over the entire range of concentration$ (4) $Does not obey Raoult's law$ 77. $The molal elevation constant is the ratio of elevation in boiling point to$ (1) $molarity$ (2) $molality$ (3) $mole fraction of solute$ (4) $mole fraction of solvent$ 78. $During osmosis, flow of water through a semipermeable membrane is$ (1) $from solution having lower concentration only$ (2) $from solution having higher concentration only$ (3) $from both sides of semipermeable membrane with equal flow rates$ (4) $from both sides of semipermeable membrane with unequal flow rates.$ 79. $When 10^{- 3} M solution of glucose in water, freezes at - 0.0186^{\circ} C, then at what temperature 10^{- 3} M solution of NaCl will freeze?$ (1) $0^{\circ} C$ (2) $0.186^{\circ} C$ (3) $- 0.186^{\circ} C$ (4) $- 0.0372^{\circ} C$ 80. $A camphor sample melts at 176^{\circ} C . K_{f} for camphor is 40 K kg mol^{- 1} . A solution of 0.02 g of a hydrocarbon in 0.8 g of camphor melts at 156.77^{\circ} C . The hydrocarbon is made up of 92.3 % of carbon. What is the molecular formula of the hydrocarbon?$ (1) $C_{6} H_{6}$ (2) $C_{12} H_{12}$ (3) $C_{4} H_{4}$ (4) $C_{8} H_{8}$ 81. $The van’t Hoff factor for 0.1 M Ba (N O_{3})_{2} solution is 2.74. The degree of dissociation is :$ (1) $91.3%$ (2) $87%$ (3) $100%$ (4) $74%$ 82. $Which one of the following 0.06M aqueous solutions has lowest freezing point?$ (1) $A l_{2} (S O_{4})_{3}$ (2) $C_{6} H_{12} O_{6}$ (3) $KI$ (4) $K_{2} S O_{4}$ 83. $1 g of a non-volatile non-electrolyte solute is dissolved in 100 g of two different solvents A and B whose ebullioscopic constants are in the ratio of 1 : 5. The ratio of the elevation in their boiling points, \frac{Δ Tb ( A )}{Δ Tb ( B )}, is :$ (1) $5:1$ (2) $10:1$ (3) $1:5$ (4) $1:02$ 84. $On mixing, heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0 g of heptane and 35 g of octane will be (molar mass of heptane = 100 g m o l^{-1} and of octane = 114 g m o l^{-1})$ (1) $72.0 kPa$ (2) $36.1 kPa$ (3) $96.2 kPa$ (4) $144.5 kPa$ 85. $What is the molality of a solution containing 200 mg of urea (molar mass = 60 g mol^{- 1}) dissolved in 40 g of water?$ (1) $0.0825$ (2) $0.825$ (3) $0.498$ (4) $0.0013$ 86. $Benzene and toluene form nearly ideal solutions. At 20ºC, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of benzene at 20 ºC for a solution containing 78 g of benzene and 46 g of toluene in torr is:$ (1) $50$ (2) $25$ (3) $37.5$ (4) $53.5$ 87. $The vapour pressure of pure CCl_{4} (molar mass = 154 g (mol^{- 1}) and SnCl_{4} () molar mass (= 170 g mol^{- 1}) at 25^{\circ} C are 115.0 and 238.0 torr respectively. Assuming ideal behaviour, calculate the total approximate vapour pressure in torr of a solution containing 10 g of CCl_{4} and 15 g of SnCl_{4} .$ (1) $185.85$ (2) $190.0$ (3) $180.7$ (4) $182.1$ 88. $What is the mole fraction of the solute in a 1.00 aqueous solution?$ (1) $1.770$ (2) $0.0354$ (3) $0.0177$ (4) $0.177$ 89. $The vapour pressure of pure water is 23 mmHg . The vapour pressure of an aqueous solution, which contains 10 mass per cent of solute ' A' having molecular weight 50 is$ (1) $0.003 atm$ (2) $34.5 atm$ (3) $22 atm$ (4) $0.028 atm$ 90. $An aqueous solution is 1.00 molal in K I . Which change will cause the vapour pressure of the solution to increase?$ (1) $Addition of N a C l$ (2) $Addition of N a_{2} S O_{4}$ (3) $Addition of 1.00 molal KI$ (4) $Addition of water$