Solutions PYQs Set 9 (PDF)

Set 9 of 12 · Questions 241-270 of 332

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Mere Teacher · Previous Year Questions NEET Chemistry · Solutions · Set 9 (Q241-270)
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241. $A solution containing 10 g per d m^{3} of urea (molecular mass = 60 g m o l^{- 1}) is isotonic with a 5% solution of a nonvolatile solute is$ (1) $200 g m o l^{- 1}$ (2) $250 g m o l^{- 1}$ (3) $300 g m o l^{- 1}$ (4) $350 g m o l^{- 1}$ 242. $Concentrated aqueous sulphuric acid is 98% H_{2} S O_{4} by mass and has a density of 1.80 g m L^{- 1} . Volume of acid required to make one litre of 0.1 M H_{2} S O_{4} solution is$ (1) $16.65 m L$ (2) $22.20 m L$ (3) $5.55 m L$ (4) $11.10 m L$ 243. $Calculate the approximate Δ T_{b} (in K) for 0.001 molal KCl solution, if its van't-Hoff factor is 1.98 (K_{b}) of water is 0.52 K kg mol^{- 1}]$ (1) $1.03$ (2) $1.03 \times 10^{- 3}$ (3) $1.03 \times 10^{- 5}$ (4) $1.03 \times 10^{- 1}$ 244. $The elevation in the boiling point of aqueous urea solution is 0.104 K . What is its Δ T_{f} (in K) value? (for Water (K_{b} = 0.52 K kg mol^{- 1}, K_{f} = 1.86 K kg mol^{- 1})$ (1) $0.0186$ (2) $0.186$ (3) $0.372$ (4) $0.0372$ 245. $2.5litre of 1 MNaOH solution is mixed with another 3litre of 0.5 MNaOH solution. Then find out molarity of resultant solution.$ (1) $0.80 M$ (2) $1.0 M$ (3) $0.73 M$ (4) $0.50 M$ 246. $The size of a raw mango shrinks to a much smaller size when kept in a concentrated salt solution. Which one of the following processes can explain this?$ (1) $Osmosis$ (2) $Reverse osmosis$ (3) $Diffusion$ (4) $Dialysis$ 247. $Which of the following units is useful in relating concentration of solution with its vapour pressure?$ (1) $Mole fraction$ (2) $Parts per million$ (3) $Mass percentage$ (4) $Molality$ 248. $A solution of non-volatile solute is obtained by dissolving 3.5 g in 100 g solvent has boiling point elevation 0.35 K . Calculate the molar mass of solute. (Molal elevation constant = 2.5 K kg mol^{- 1})$ (1) $270 g mol^{- 1}$ (2) $250 g mol^{- 1}$ (3) $260 g mol^{- 1}$ (4) $240 g mol^{- 1}$ 249. $If the osmotic pressure of cane sugar solution is 2.46 atm at 27^{\circ} C, then what is the concentration (in mol L^{- 1}) of the solution (R = 0.0821 L atm mol^{- 1} K^{- 1})$ (1) $0.1$ (2) $0.2$ (3) $0.01$ (4) $0.02$ 250. $At , the Henry law constant in water for and are bar and bar respectively. What is the ratio of mole fractions of and in water?(Assume partial pressures of and same at )$ (1) $2.19$ (2) $0.95$ (3) $0.60$ (4) $0.45$ 251. $The empirical formula of a non-electrolyte is CH_{2} O . A solution containing 6 g of the compound exerts the same osmotic pressure as that of 0.05 M glucose solution at the same temperature. The molecular formula of the compound is$ (1) $C_{2} H_{4} O_{2}$ (2) $C_{3} H_{6} O_{3}$ (3) $C_{5} H_{10} O_{5}$ (4) $C_{4} H_{8} O_{4}$ 252. $Henry's law constant for the solubility of gas in water at is . The mole fraction of in air is 0.8 . The number of moles of from air dissolved in 10 moles of water at and pressure is$ (1) $4.0 \times 10^{- 4}$ (2) $5.0 \times 10^{- 4}$ (3) $4.0 \times 10^{- 5}$ (4) $4.0 \times 10^{- 6}$ 253. $A solvent freezes at 17^{\circ} C and it has latent heat of fusion 180 J g^{- 1} . The molal depression constant of the solvent is [units of K_{f} = Kkg mol^{- 1}]$ (1) $3.88$ (2) $3.55$ (3) $3.70$ (4) $4.77$ 254. $160 g of non-volatile solute ' A' is dissolved in 54 mL of water at 373 K . What is the vapour pressure of aqueous solution of A . (Given, molecular weight of A = 160 g mol^{- 1})$ (1) $760 Torr$ (2) $720 Torr$ (3) $570 Torr$ (4) $450 Torr$ 255. $When 2.44 grams of benzoic acid (C_{6} H_{5} COOH) dissolved in 25 grams of benzene, it shows depression of freezing point equal to 2.2 K . Molal depression constant of benzene is 5.0 K kg mol^{- 1} . What is the percentage association of acid, if it forms dimer in solution?$ (1) $50 %$ (2) $77 %$ (3) $95 %$ (4) $90 %$ 256. $When a non-volatile solute is added to the solvent, the vapour pressure of the solventdecreases by 10 mm of Hg. The mole fraction of the solute in the solution is 0.2. What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg?$ (1) $0.8$ (2) $0.4$ (3) $0.2$ (4) $0.6$ 257. $A solution containing 62 g ethylene glycol in 250 g water is cooled to -10ºC. If K_{f} for water is 1.86 K kg m o l^{-1}, the amount of water (in g) separated as ice is:$ (1) $16$ (2) $32$ (3) $48$ (4) $64$ 258. $Match List - I with List - II. List - I (A) Solution of chloroform and acetone (B) Solution of ethanol and water (C) Solution of benzene and toluene (D) Solution of acetic acid in benzene List - II (I) Minimum boiling azeotrope (II) Dimerizes (III) Maximum boiling azeotrope (IV) Δ V_{mix} = 0 Choose the correct answer from the options given below:$ (1) $(A)-(III), (B)-(I), (C)-(IV), (D)-(II)$ (2) $(A)-(III), (B)-(IV), (C)-(I), (D)-(II)$ (3) $(A)-(II), (B)-(I), (C)-(IV), (D)-(III)$ (4) $(A)-(II), (B)-(IV), (C)-(I), (D)-(III)$ 259. $and are the vapour pressure of pure liquid components, and , respectively of an ideal binary solution. If represents the mole fraction ofcomponent , the total pressure of the solution will be$ (1) $p_{A} + x_{A} (p_{B} - p_{A})$ (2) $p_{A} + x_{A} (p_{A} - p_{B})$ (3) $p_{B} + x_{A} (p_{B} - p_{A})$ (4) $p_{B} + x_{A} (p_{A} - p_{B})$ 260. $The freezing point of benzene decreases by 0.45ºC when 0.2 g of acetic acid is added to 20 g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be : (K_{f} for benzene = 5.12 K kg m o l^{-1})$ (1) $80.4%$ (2) $74.6%$ (3) $94.6%$ (4) $64.6%$ 261. $A solution of urea (mol. mass 56 g m o l^{- 1}) boils at 100. 18 C at the atmospheric pressure. If K_{f} and K_{b} for water are 1.86 and 0.512 K kg m o l^{- 1} respectively, the above solution will freeze at$ (1) $0. 654 C$ (2) $- 0.654 C$ (3) $6. 54 C$ (4) $- 6.54 C$ 262. $Boiling point of a 2% aqueous solution of a nonvolatile solute A is equal to the boiling point of 8% aqueous solution of a non-volatile solute B. The relation between molecular weights of A and B is.$ (1) $M_{A} = 4 M_{B}$ (2) $M_{b} = 4 M_{A}$ (3) $M_{A} = 8 M_{B}$ (4) $M_{B} = 8 M_{A}$ 263. $If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water (∆ T_{f}), when 0.01 mole of sodium sulphate is dissolved in 1 kg of water, is (K_{f} = 1.86 K kg mol^{-1})$ (1) $0.0372 K$ (2) $0.0558 K$ (3) $0.0744 K$ (4) $0.0186 K$ 264. $A graph of vapour pressure and temperature for three different liquids X, Y and Z is shown below:The following inferences are made:(A) Intermolecular force of attraction of X > Y (B) Intermolecular force of attraction of X < Y .(C) Intermolecular force of attraction of Z<X.$ (1) $A and C$ (2) $A and B$ (3) $B only$ (4) $B and C$ 265. $Which of the following salt has the same value of vant’s Hoff factor (i) as that of K_{3} [Fe (CN)_{6}] ?$ (1) $N a_{2} S O_{4}$ (2) $A l (N O_{3})_{3}$ (3) $A l_{2} (S O_{4})_{3}$ (4) $N a C l$ 266. $Which one of the following graphs accurately represents the plot of partial pressure of vs its mole fraction in a mixture of acetone and at constant temperature?$ (1) (2) (3) (4) 267. $In the depression of freezing point experiment A. Vapour pressure of the solution is less than that of pure solvent B. Vapour pressure of the solution is more than that of pure solvent C. Only solute molecules solidify at the freezing point D. Only solvent molecules solidify at the freezing point$ (1) $A and D only$ (2) $B and C only$ (3) $A and C only$ (4) $A only$ 268. $Which of the following properties will change when system containing solution 1 will become solution 2?$ (1) $Molar heat capacity$ (2) $Concentration$ (3) $Gibbs free energy$ (4) $Density$ 269. $Two 5 molal solutions are prepared by dissolving a non-electrolyte non-volotatile solute separately in the solvents X and Y. The molecular weights of the solvents are M_{X} and M_{Y}, respectively where M_{X} = \frac{3}{4} M_{Y} . The relative lowering of vapour pressure of the solution in X is "m" times that of the solution in Y. Given that the number of moles of solute is very small in comparison to that of solvent, the value of "m" is :$ (1) $\frac{4}{3}$ (2) $\frac{3}{4}$ (3) $\frac{1}{2}$ (4) $\frac{1}{4}$ 270. $Which of the following statements about the composition of the vapour over an ideal 1 : 1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at 2 5^{o} C . (Given, vapour pressure data at 2 5^{o} C, benzene = 12.8 k P a, toluene = 3.85 k P a)$ (1) $The vapour will contain equal amounts of benzene and toluene.$ (2) $Not enough information is given to make a prediction.$ (3) $The vapour will contain a higher percentage of benzene.$ (4) $The vapour will contain a higher percentage of toluene.$