Solutions PYQs Set 10 (PDF)

Set 10 of 14 · Questions 271-300 of 419

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Solutions · Set 10 (Q271-300)
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271. $A solution at 20ºC is composed of 1.5 mol of benzene and 3.5 mol of toluene. If the vapour pressure of pure benzene and pure toluene at this temperature are 74.7 torr and 22.3 torr, respectively, then the total vapour pressure of the solution and the benzene mole fraction in equilibrium with it will be, respectively$ (1) $35.0 torr and 0.480$ (2) $30.5 torr and 0.389$ (3) $38.0 torr and 0.589$ (4) $35.8 torr and 0.280$ 272. $At 0^{\circ} C urea solution has an osmotic pressure if 400 mm . On dilution by x times, its osmotic pressure decreased to 100 mm at 20^{\circ} C . The dilution factor x is approximately$ (1) $4.3$ (2) $2$ (3) $5$ (4) $6.8$ 273. $Which of the following solutions will exhibit highest boiling point?$ (1) $0.01 M Na_{2} SO_{4 (aq)}$ (2) $0.01 M KNO_{3 (aq)}$ (3) $0.015M urea (aq)$ (4) $0.015M glucose e_{(aq)}$ 274. $A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60g m o l^{-1}) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g c m^{-3}, molar mass of the substance will be$ (1) $105.0 g m o l^{-1}$ (2) $210.0 g m o l^{-1}$ (3) $90.0 g m o l^{-1}$ (4) $15.0 g m o l^{-1}$ 275. $The vapour pressures of two liquids and in their pure states are in ratio of . binary solution of and contains and in the mole proportion of . The mole fraction of in the vapour phase of the solution will be$ (1) $0.33$ (2) $0.2$ (3) $0.25$ (4) $0.52$ 276. $Which among the following is not colligative property?$ (1) $Vapour pressure lowering$ (2) $Boiling point$ (3) $Freezing point depression$ (4) $Osmotic pressure$ 277. $To 500 c m^{3} of water, 3.0 \times 1 0^{-3} kg of acetic acid is added. If 23% of acetic acid is dissociated, what will be the depression in freezing point? k_{f} and density of water are 1.86 K k g m o l e^{-1} and 0.997 g c m^{-3} respectively$ (1) $0.186 K$ (2) $0.228 K$ (3) $0.372 K$ (4) $0.556 K$ 278. $0.2 M aqueous solution of glucose has osmotic pressure 4.9 atm at 300 K . What is the concentration of glucose if it has osmotic pressure 1.5 atm at same temperature?$ (1) $0.03 M$ (2) $0.04 M$ (3) $0.05 M$ (4) $0.06 M$ 279. $Which condition is not satisfied by an ideal solution?$ (1) $∆_{mi x} V = 0$ (2) $∆_{mi x} S = 0$ (3) $Obeyance to Raoult’s Law$ (4) $∆_{mi x} H = 0$ 280. $Commercially available H_{2} SO_{4} is 98 g by weight of H_{2} SO_{4} and 2 g by weight of water. It's density is 1.38 g cm^{- 3} . Calculate the molality (m) of H_{2} SO_{4} (molar mass of H_{2} SO_{4} is 98 g mol^{- 1})$ (1) $500 m$ (2) $20 molal$ (3) $50 m$ (4) $200 m$ 281. $Molecules of benzoic acid (C_{6} H_{5} COOH) dimerise in benzene. ‘w’ g of the acid dissolved in 30 g of benzene shows a depression in freezing point equal to 2 K. If the percentage association of the acid to form dimer in the solution is 80, then w is :(Given that K_{f} = 5 kg m o l^{-1}, Molar mass of benzoic acid = 122 g m o l^{-1})$ (1) $2.4 g$ (2) $1.8 g$ (3) $1.0 g$ (4) $1.5 g$ 282. $A solution containing 10 g per d m^{3} of urea (molecular mass = 60 g m o l^{- 1}) is isotonic with a 5% solution of a nonvolatile solute is$ (1) $200 g m o l^{- 1}$ (2) $250 g m o l^{- 1}$ (3) $300 g m o l^{- 1}$ (4) $350 g m o l^{- 1}$ 283. $Concentrated aqueous sulphuric acid is 98% H_{2} S O_{4} by mass and has a density of 1.80 g m L^{- 1} . Volume of acid required to make one litre of 0.1 M H_{2} S O_{4} solution is$ (1) $16.65 m L$ (2) $22.20 m L$ (3) $5.55 m L$ (4) $11.10 m L$ 284. $Calculate the approximate Δ T_{b} (in K) for 0.001 molal KCl solution, if its van't-Hoff factor is 1.98 (K_{b}) of water is 0.52 K kg mol^{- 1}]$ (1) $1.03$ (2) $1.03 \times 10^{- 3}$ (3) $1.03 \times 10^{- 5}$ (4) $1.03 \times 10^{- 1}$ 285. $The elevation in the boiling point of aqueous urea solution is 0.104 K . What is its Δ T_{f} (in K) value? (for Water (K_{b} = 0.52 K kg mol^{- 1}, K_{f} = 1.86 K kg mol^{- 1})$ (1) $0.0186$ (2) $0.186$ (3) $0.372$ (4) $0.0372$ 286. $2.5litre of 1 MNaOH solution is mixed with another 3litre of 0.5 MNaOH solution. Then find out molarity of resultant solution.$ (1) $0.80 M$ (2) $1.0 M$ (3) $0.73 M$ (4) $0.50 M$ 287. $The size of a raw mango shrinks to a much smaller size when kept in a concentrated salt solution. Which one of the following processes can explain this?$ (1) $Osmosis$ (2) $Reverse osmosis$ (3) $Diffusion$ (4) $Dialysis$ 288. $Which of the following units is useful in relating concentration of solution with its vapour pressure?$ (1) $Mole fraction$ (2) $Parts per million$ (3) $Mass percentage$ (4) $Molality$ 289. $A solution of non-volatile solute is obtained by dissolving 3.5 g in 100 g solvent has boiling point elevation 0.35 K . Calculate the molar mass of solute. (Molal elevation constant = 2.5 K kg mol^{- 1})$ (1) $270 g mol^{- 1}$ (2) $250 g mol^{- 1}$ (3) $260 g mol^{- 1}$ (4) $240 g mol^{- 1}$ 290. $If the osmotic pressure of cane sugar solution is 2.46 atm at 27^{\circ} C, then what is the concentration (in mol L^{- 1}) of the solution (R = 0.0821 L atm mol^{- 1} K^{- 1})$ (1) $0.1$ (2) $0.2$ (3) $0.01$ (4) $0.02$ 291. $At , the Henry law constant in water for and are bar and bar respectively. What is the ratio of mole fractions of and in water?(Assume partial pressures of and same at )$ (1) $2.19$ (2) $0.95$ (3) $0.60$ (4) $0.45$ 292. $The empirical formula of a non-electrolyte is CH_{2} O . A solution containing 6 g of the compound exerts the same osmotic pressure as that of 0.05 M glucose solution at the same temperature. The molecular formula of the compound is$ (1) $C_{2} H_{4} O_{2}$ (2) $C_{3} H_{6} O_{3}$ (3) $C_{5} H_{10} O_{5}$ (4) $C_{4} H_{8} O_{4}$ 293. $Henry's law constant for the solubility of gas in water at is . The mole fraction of in air is 0.8 . The number of moles of from air dissolved in 10 moles of water at and pressure is$ (1) $4.0 \times 10^{- 4}$ (2) $5.0 \times 10^{- 4}$ (3) $4.0 \times 10^{- 5}$ (4) $4.0 \times 10^{- 6}$ 294. $A solvent freezes at 17^{\circ} C and it has latent heat of fusion 180 J g^{- 1} . The molal depression constant of the solvent is [units of K_{f} = Kkg mol^{- 1}]$ (1) $3.88$ (2) $3.55$ (3) $3.70$ (4) $4.77$ 295. $160 g of non-volatile solute ' A' is dissolved in 54 mL of water at 373 K . What is the vapour pressure of aqueous solution of A . (Given, molecular weight of A = 160 g mol^{- 1})$ (1) $760 Torr$ (2) $720 Torr$ (3) $570 Torr$ (4) $450 Torr$ 296. $When 2.44 grams of benzoic acid (C_{6} H_{5} COOH) dissolved in 25 grams of benzene, it shows depression of freezing point equal to 2.2 K . Molal depression constant of benzene is 5.0 K kg mol^{- 1} . What is the percentage association of acid, if it forms dimer in solution?$ (1) $50 %$ (2) $77 %$ (3) $95 %$ (4) $90 %$ 297. $When a non-volatile solute is added to the solvent, the vapour pressure of the solventdecreases by 10 mm of Hg. The mole fraction of the solute in the solution is 0.2. What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg?$ (1) $0.8$ (2) $0.4$ (3) $0.2$ (4) $0.6$ 298. $Lead storage battery contains 38% by weight solution of H_{2} S O_{4} . The van't Hoff factor is 2.67 at this concentration. The temperature in Kelvin at which the solution in the battery will freeze is____ (Nearest integer). Given K_{f} = 1. 8 K k g m o l^{- 1}$ 299. $The mass of sodium acetate (CH_{3} COONa) required to prepare 250 mL of 0.35 M aqueous solution is_____g. (Molar mass of CH_{3} COONa is 82.02 g mol^{- 1})$ 300. $If a compound AB dissociates to the extent of 75% in an aqueous solution, the molality of the solution which shows a 2.5 K rise in the boiling point of the solution is ____ molar . (Rounded-off to the nearest integer) (K_{b} = 0.52 K kg mol^{- 1})$