Solutions: MCQs | Question – Paper 2 1

58.5 gm of NaCl and 180 gm of glucose were separately dissolved in 1000 ml of water. Identify the correct statement regarding the elevation of boiling point (b.p.) of the resulting solutions. [West Bengal JEE]

The freezing point (in °C) of a solution containing 0.1 g of K₃[Fe(CN)₆] (Mol. Wt. 329) in 100 g water

(K_f = 1.86 K kg mol^–1) is [IIT JEE 2011]

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: (K_f for water = 1.86 K kg mol^–1 and molar mass of ethylene glycol = 62 g mol^–1) [AIEEE 2011]

A 5% solution of cane sugar (molar mass 342 is isotonic with 1% of a solution of an unknown solute. The molar mass of unknown solute in g/mol is [AIEEE 2011]

A solution of sucrose (molar mass = 342 g mol^-1) has been prepared by dissolving 68.5 g of sucrose in 100 g of water. The freezing point of the solution obtained will be (K_f for water = 1.86 K kg mol^-1) [CBSE AIPMT 2010]

An aqueous solution is 1.00 molal in KI. Which change will cause the vapour pressure of the solution to increase? [CBSE AIPMT 2010]

25.3 g of sodium carbonate, Na₂CO₃ is dissolved in enough water to make 250 ml of solution. If sodium carbonate dissociates completely, molar concentration of sodium Ion, Na⁺ and carbonate ions, CO₃^2- are respectively (Molar mass of Na_sCO₃ = 106 g mol^-1) [CBSE AIPMT 2010]

On mixing, heptanes and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components (heptanes and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0 g of heptanes and 35 g of octane will be (molar mass of heptanes = 100 g mol^-1 and of octane = 114 g mol^-1) [AIEEE 2010]

If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water
(ΔT_f), when 0.01 mol of sodium sulphate is dissolved in 1 kg of water is (K_f = 1.86 K kg mol^-1) [AIEEE 2010]

The molarity of a NaOH solution by dissolving 4 g of it in 250 ml water is [West Bengal JEE 2010]

What is the osmotic pressure of a 0.0020 mol dm^-3 sucrose (C₁₂H₂₂O₁₁) solution at 20°C?

(Molar gas constant, R = 8.314 JK^-1 mol^-1, 1 dm³ = 0.001 m³? [Delhi PMT 2010]

The Henry's law constant for the solubility of N₂ gas in water at 298 K is 1.0 ´ 10⁵ atm. The mole fraction of N₂ in air is 0.8. The number of moles of N₂ from air dissolved in 10 moles of water at 298 K and 5 atm pressure is [IIT JEE 2009]

0.5 molal aqueous solution of a weak acid (HX) is 20% ionized. If K_f for water is 1.86 K kg mol^-1, the lowering in freezing point of the solution is [CBSE AIPMT 2007]

A solution containing 10 g per dm³ of urea (molecular mass = 60) is isotonic with a 5% solution of a non-volatile solute. The molecular mass of this non-volatile solute is [CBSE AIPMT 2006]

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 [AIEEE 2005]