Solutions PYQs Set 1 (PDF)

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Mere Teacher · Previous Year Questions JEE Main Chemistry · Solutions · Set 1 (Q1-30)
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1. $The freezing point of a diluted milk sample is found to be - 0.2° C, while it should have been - 0.5° C for pure milk. How much water has been added to pure milk to make the diluted sample?$ (1) $1 cup of water to 2 cups of pure milk$ (2) $3 cups of water to 2 cups of pure milk$ (3) $1 cup of water to 3 cups of pure milk$ (4) $2 cups of water to 3 cups of pure milk$ 2. $K_{f} for water is 1.86 K kg m o l^{-1} . If your automobile radiator holds 1.0 kg of water, how may grams of ethylene glycol (C_{2} H_{6} O_{2}) must you add to get the freezing point of the solution lowered to -2.8ºC?$ (1) $72 g$ (2) $93 g$ (3) $39 g$ (4) $27 g$ 3. $If aqueous solution contains 9 % and 1 % (w / w) of two non-volatile non-electrolytes X (molecular weight 180) and Y (molecular weight 50) respectively, the boiling point of solution in^{\circ} C approximately is (K_{b} = 0.52 K kg mol^{- 1})$ (1) $101.4$ (2) $100.4$ (3) $102.4$ (4) $100.8$ 4. $A 6 % solution of urea is isotonic with$ (1) $0.05 M solution of glucose$ (2) $6 % solution of glucose$ (3) $25 % solution of glucose$ (4) $1 M solution of glucose.$ 5. $Consider a solution of dissolved in water in a closed container. Which one of the following plots correctly represents variation of (partial pressure of in vapour phase above water) -axis] with (mole fraction of in water) -axis at ?$ (1) (2) (3) (4) 6. $The Molarity (M) of an aqueous solution containing 5.85 g of NaCl in 500 mL water is : (Given : Molar Mass Na : 23 and Cl : 35.5 gmol^{- 1})$ (1) $2$ (2) $20$ (3) $4$ (4) $0.2$ 7. $At T (K) \times g of a non-volatile solid (molar mass 78 g mol^{- 1}) when added to 0.5 kg water, lowered its freezing point by 1.0^{\circ} C . What is x (in (g) ? (K_{f}) of water at T (K) = (1.86 KKg mol^{- 1})$ (1) $10.48$ (2) $20.96$ (3) $41.92$ (4) $5.24$ 8. $200 m L of an aqueous solution of a protein contains its 1.26 g . The osmotic pressure of this solution at 300 K is found to be 2.57 \times 1 0^{- 3} bar. The molar mass of protein will be (R = 0.083 L bar m o l^{- 1} K^{- 1})$ (1) $51022 g m o l^{- 1}$ (2) $122044 g m o l^{- 1}$ (3) $31011 g m o l^{- 1}$ (4) $61038 g m o l^{- 1}$ 9. $Which of the following pair of solutions is isotonic? A. 18 g / L of glucose of solution and 6 g / L of Urea solution B. 10 g / L of glucose solution and 10 g / L of Urea solution C. 0.01 MNaOH solution and 0.02 M glucose solution D. 0.01 MNaCl solution and 0.01 M glucose solution (Assume that NaCl undergoes complete dissociation)$ (1) $A and B$ (2) $A and C$ (3) $B and D$ (4) $B and C$ 10. $A solution of two liquids boils at a temperature more than the boiling point of either of them. Hence, the binary solution shows$ (1) $negative deviation from Raoult's law$ (2) $positive deviation from Raoult's law$ (3) $no deviation from Raoult's law$ (4) $positive or negative deviation from Raoult's law depending upon the composition.$ 11. $Assertion (A) : For an endothermic dissolution process, increase in temperature increases the solubility in a nearly saturated solution. Reason (R) : In saturated solution dynamic equilibrium exists between dissolved solute and undissolved solute.$ (1) $Both (A) and (R) are correct and R is the correct explanation of A$ (2) $Both (A) and (R) are correct, but R is not the correct explanation of A$ (3) $(A) is correct but (R) is not correct$ (4) $(A) is incorrect but (R) is correct$ 12. $If the K_{H} values for Ar (g), CO_{2} (g), HCHO (g) and CH_{4} (g) respectively are 40.39, 1.67, 1.83 \times 10^{- 5} and 0.413 , then identify the correct increasing order of their solubilities.$ (1) $HCHO < CH_{4} < CO_{2} < Ar$ (2) $HCHO < CO_{2} < CH_{4} < Ar$ (3) $Ar < CO_{2} < HCHO < CH_{4}$ (4) $Ar < CO_{2} < CH_{4} < HCHO$ 13. $A solution is made by mixing one mole of volatile liquid A with 3 moles of volatile liquid B . The vapour pressure of pure A is 200 mm Hg and that of the solution is 500 mm Hg. The vapour pressure of pure B and the least volatile component of the solution, respectively, are:$ (1) $1400 mm Hg, A$ (2) $1400 mm Hg, B$ (3) $600 mm Hg, A$ (4) $600 mm Hg, B$ 14. $At 298 K, if the vapour pressure of pure liquids toluene, benzene, chloroform and dichloromethane are 60,160 , 200 and 415 torr respectively. Then which liquid is having high boiling point?$ (1) $Toluene$ (2) $Benzene$ (3) $Chloroform$ (4) $Dichloromethane$ 15. $Solute A associates in water. When 0.7 g of solute A is dissolved in 42.0 g of water, it depresses the freezing point by 0.2°C. The percentage association of solute A in water, is [Given : Molar mass of A = 93 g m o l^{- 1} . Molal depression constant of water is 1.86 K kg m o l^{- 1}]$ (1) $50 %$ (2) $60 %$ (3) $70 %$ (4) $80 %$ 16. $8 g of NaOH is dissolved in 18 g of . Mole fraction of NaOH in solution and molality (in mol) of the solution respectively are :$ (1) $0.2, 22.20$ (2) $0.2, 11.11$ (3) $0.167, 11.11$ (4) $0.167, 22.20$ 17. $0.5 molal aqueous solution of a weak acid (^{H X}) is 20% ionised. If K_{f} for water is 1.86 K kg m o 1^{- 1}, the lowering in freezing point of the solution is$ (1) $0.56 K$ (2) $1.12 K$ (3) $- 0.56 K$ (4) $- 1.12 K$ 18. $What is the boiling point of solution of 0.1 mKCl ? K_{b} of water is 0.52 K kg mol^{- 1} . (α = 100 %) (water boil at 373 K)$ (1) $100.104 K$ (2) $373.104 K$ (3) $273.104 K$ (4) $373.052 K$ 19. $The mixture which shows positive deviation from Raoult's law is:$ (1) $Benzene + Toluene$ (2) $Acetone + Chloroform$ (3) $Chloroethane + Bromoethane$ (4) $Ethanol + Acetone$ 20. $Liquid ‘M’ and liquid ‘N’ form an ideal solution. The vapour pressures of pure liquids ‘M’ and ‘N’ are 450 and 700 mmHg, respectively, at the same temperature. Then correct statements is : (xM = Mole fraction of ‘M’ in solution ; xN = Mole fraction of ‘N’ in solution; yM = Mole fraction of ‘M’ in vapour phase; yN = Mole fraction of ‘N’ in vapour phase)$ (1) $\frac{x _{M}}{x _{N}} = \frac{y _{M}}{y _{N}}$ (2) $(x_{M} - y_{M}) < (x_{N} - y_{N})$ (3) $\frac{x _{M}}{x _{N}} < \frac{y _{M}}{y _{N}}$ (4) $\frac{x _{M}}{x _{N}} > \frac{y _{M}}{y _{N}}$ 21. $When 20 g of naphthoic acid (C_{11} H_{8} O_{2}) is dissolved in 50 g of benzene (K_{f} = 1.72 K kg m o l^{-1}), a freezing point depression of 2 K is observed. The van’t Hoff factor (i) is:$ (1) $0.5$ (2) $1$ (3) $2$ (4) $3$ 22. $The vapour pressure of a solvent decreased by 10 mm ofmercury when a non‐volatile solute was added to the solvent. The mole fraction ofthe solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of mercury?$ (1) $0.4$ (2) $0.6$ (3) $0.8$ (4) $0.2$ 23. $15 % aqueous solution of glucose (molecular weight = 180 g / mol) is isotonic with 8 % aqueous solution containing an unknown non-dissociable solute. What is the molecular weight of the unknown solute?$ (1) $108$ (2) $96$ (3) $84$ (4) $9.6$ 24. $A solution containing components A and B follows Raoult’s law$ (1) $A ‐B attraction force is greater than A ‐A and B‐B$ (2) $A‐B attraction force is less than A‐A and B ‐B$ (3) $A ‐B attraction force remains same as A ‐A and B‐B$ (4) $volume of solution is different from sum of volume of solute and solvent.$ 25. $The vapour pressure of water at 20ºC is 17.5 mm Hg. If 18 g of glucose (C_{6} H_{12} O_{6}) is added to 178.2g of water at 20°C, the vapour pressure of the resulting solution will be$ (1) $15.750 mm Hg$ (2) $16.500 mm Hg$ (3) $17.325 mm Hg$ (4) $17.675 mm Hg$ 26. $The quantity which changes with temperature is:$ (1) $Molarity$ (2) $Mass percentage$ (3) $Molality$ (4) $Mole fraction$ 27. $Mass of ethylene glycol (antifreeze) to be added to 18.6 kg of water to protect the freezing point at - 24^{\circ} C is______kg (Molar mass in gmol^{- 1} for ethylene glycol 62, K_{f} of water = 1.86 K kg mol^{- 1})$ 28. $The elevation of boiling point of 0.10 m aqueous CrCl_{3} \cdot xNH_{3} solution is two times that of 0.05 m aqueous CaCl_{2} solution. The value of x is [Assume 100 % ionisation of the complex and CaCl_{2}, coordination number of Cr as 6, and that all NH_{3} molecules are present inside thecoordination sphere]$ 29. $How much amount of NaCl should be added to 600 g for water (ρ = 1.00 g / mL) to decrease the freezing point of water to - 0.2^{\circ} C ? ..... (The freezing point depression constant of water = 2 Kkg mo l^{- 1}$ 30. $AB_{2} is 10 % dissociated in water to A^{2 +} and B^{-} The boiling point of a 10.0 molal aqueous solution of AB_{2} is_______^{\circ} C . (Round off to the Nearest Integer). [Given : Molal elevation constant of water K_{b} = 0.5 Kkg mol^{- 1} boiling point of pure water (= 100^{\circ} C)$