Chapter 5

KBr is \(80 \%\) dissociated in aqueous solution of \(0.5 \mathrm{M}\) concentration. (Given \(\mathrm{K}_{t}\) for water \(=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\) ). The solution freezes at (a) \(271.326 \mathrm{~K}\) (b) \(272 \mathrm{~K}\) (c) \(270.5 \mathrm{~K}\) (d) \(268.5 \mathrm{~K}\)

If at certain temperature the vapour pressure of pure water is \(25 \mathrm{~mm}\) of \(\mathrm{Hg}\) and that of a very dilute aqueous urea solution is \(24.5 \mathrm{~mm}\) of \(\mathrm{Hg}\), the molality of the solution is (a) \(0.02\) (b) \(1.2\) (c) \(1.11\) (d) \(0.08\)

Benzoic acid undergoes dimerization in benzene solution, the van't Hoff factor 'i' is related to the degree of association ' \(\mathrm{x}\) ' of to the acid as (a) \(\mathrm{i}=(1+\mathrm{x})\) (b) \(\mathrm{i}=(1-\mathrm{x})\) (c) \(\mathrm{i}=(1-\mathrm{x} / 2)\) (d) \(\mathrm{i}=(1+\mathrm{x} / 2)\)

The vapour pressure of water at \(300 \mathrm{~K}\) in a closed container is \(0.4 \mathrm{~atm}\). If the volume of the container is doubled, its vapour pressure at \(300 \mathrm{~K}\) will be (a) \(0.8 \mathrm{~atm}\) (b) \(0.2 \mathrm{~atm}\) (c) \(0.4 \mathrm{~atm}\) (d) \(0.6 \mathrm{~atm}\)

A solution is obtained by dissolving \(6 \mathrm{~g}\) of urea (mol. wt \(=60\) ) in a litre solution, another solution is prepared by dissolving \(34.2 \mathrm{~g}\) of cane sugar (mol. \(\mathrm{wt}=342\) ) in a litre of solution at the same temperature The lowering of vapour pressure in the first solution is (a) same as that of second solution (b) double that of second solution (c) half that of second solution (d) nearly one fifth of the second solution

The aqueous solution that has the lowest vapour pressure at a given temperature is (a) \(0.1\) molal sodium phosphate (b) \(0.1\) molal barium chloride (c) \(0.1\) molal sodium chloride (d) \(0.1\) molal glucose

What is the density (in \(\mathrm{g} \mathrm{L}^{-1}\) ) of \(\mathrm{CO}_{2}\) at \(400 \mathrm{~K}\) and exerting a pressure of \(0.0821 \mathrm{~atm} ?(\mathrm{R}=0.0821 \mathrm{~L} \mathrm{~atm}\) \(\left.\mathrm{mol}^{-1} \mathrm{~K}^{-1}\right)\) (a) \(0.01\) (b) \(0.11\) (c) \(2.5\) (d) 44

The vapour pressure of two liquids ' \(\mathrm{P}\) ' and ' \(\mathrm{Q}\) ' are 80 and 60 torr respectively. The total vapour pressure of solution obtained by mixing 3 mole of \(\mathrm{P}\) and \(2 \mathrm{~mol}\) of Q would be (a) 20 torr (b) 72 torr (c) 68 torr (d) 140 torr

A solution containing \(10 \mathrm{~g}\) per \(\mathrm{dm}^{3}\) of urea (molecular mass \(=60 \mathrm{~g} \mathrm{~mol}^{-1}\) ) is isotonic with a \(5 \%\) solution of a nonvolatile solute. The molecular mass of this non volatile solute is (a) \(350 \mathrm{~g} \mathrm{~mol}^{-1}\) (b) \(200 \mathrm{~g} \mathrm{~mol}^{-1}\) (c) \(250 \mathrm{~g} \mathrm{~mol}^{-\mathrm{t}}\) (d) \(300 \mathrm{~g} \mathrm{~mol}^{-1}\)

\(1.00 \mathrm{~g}\) of a non-electrolyte solute (molar mass \(250 \mathrm{~g} \mathrm{~mol}^{-1}\) ) was dissolved in \(51.2 \mathrm{~g}\) of benzene. If the freezing point depression constant, \(K_{f}\) of benzene is \(5.12 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\), the freezing point of benzene will be lowered by (a) \(0.5 \mathrm{~K}\) (b) \(0.2 \mathrm{~K}\) (c) \(0.4 \mathrm{~K}\) (d) \(0.3 \mathrm{~K}\)

If \(0.44 \mathrm{~g}\) of substance dissolved in \(22.2 \mathrm{~g}\) of benzene lowers the freezing point of benzene by \(0.567^{\circ} \mathrm{C}\), then the molecular mass of substance is, (the molal depression constant \(\left.=5.12^{\circ} \mathrm{C} \mathrm{mol}^{-1} \mathrm{~kg}\right)\) (a) \(128.4\) (b) \(156.6\) (c) \(178.9\) (d) \(232.4\)

The osmotic pressure at \(17^{\circ} \mathrm{C}\) of an aqueous solution containing \(1.75 \mathrm{~g}\) of sucrose per \(150 \mathrm{~mL}\) solution is (a) \(0.08 \mathrm{~atm}\) (b) \(8.1 \mathrm{~atm}\) (c) \(0.81\) (d) \(9.1 \mathrm{~atm}\)

By dissolving \(10 \mathrm{~g}\) of a non-volatile solute in \(100 \mathrm{~g}\) of benzene, the boiling point rises by \(1^{\circ} \mathrm{C}\). The molecular mass of solute is \(\left[\mathrm{K}_{\mathrm{b}}\right.\) for benzene \(\left.=2.53 \mathrm{~K} \mathrm{~m}^{-1}\right]\) (a) \(235 \mathrm{~g}\) (b) \(352 \mathrm{~g}\) (c) \(250 \mathrm{~g}\) (d) \(253 \mathrm{~g}\)

Among the following aqueous solutions, the correct order of increasing boiling point can be given as (i) \(10^{-4} \mathrm{M} \mathrm{KCl}\) (ii) \(10^{-3} \mathrm{M}\) urea (iii) \(10^{-3} \mathrm{M} \mathrm{CaCl}_{2}\) (iv) \(10^{-3} \mathrm{M} \mathrm{KCl}\) (a) \(\mathrm{I}<\mathrm{IV}<\mathrm{II}<\mathrm{III}\) (b) \(\mathrm{I}<\mathrm{II}<\mathrm{IV}<\mathrm{III}\) (c) \(\mathrm{IV}<\mathrm{II}<\mathrm{I}<\mathrm{III}\) (d) \(\mathrm{I}<\mathrm{II}<\mathrm{III}<\mathrm{IV}\)

Two liquids having vapour pressures \(\mathrm{P}_{1}^{0}\) and \(\mathrm{P}_{2}^{0}\) in pure state in the ratio of \(2: 1\) are mixed in a molar ratio of \(1: 2\). The ratio of their moles in the vapour state can be (a) \(2: 1\) (b) \(1: 2\) (c) \(1: 1\) (d) \(3: 3\)

Equal volumes of \(0.1 \mathrm{M} \mathrm{AgNO}_{3}\) and \(0.2 \mathrm{M} \mathrm{NaCl}\) are mixed. The concentration of nitrate ions in the mixture will be (a) \(0.1 \mathrm{M}\) (b) \(0.05 \mathrm{M}\) (c) \(0.2 \mathrm{M}\) (d) \(0.15 \mathrm{M}\)

In a depression in freezing point experiment, it is found that (1) the vapour pressure of the solution is less than that of pure solvent (2) the vapour pressure of the solution is more than that of pure solvent (3) only solute molecules solidify at the freezing point (4) only solvent molecules solidify at the freezing point (a) 1,2 (b) 2,3 (c) 1,4 (d) 1,3

On mixing \(3 \mathrm{~g}\) of non-volatile solute in \(200 \mathrm{~mL}\) of water its boiling point \(\left(100^{\circ} \mathrm{C}\right)\) becomes \(100.52^{\circ} \mathrm{C}\). If \(\mathrm{K}_{b}\) for water is \(0.6 \mathrm{~K} / \mathrm{m}\) then molecular weight of the solute is (a) \(10.5 \mathrm{~g} \mathrm{~mol}^{-1}\) (b) \(12.6 \mathrm{~g} \mathrm{~mol}^{-1}\) (c) \(15.7 \mathrm{~g} \mathrm{~mol}^{-1}\) (d) \(17.3 \mathrm{~g} \mathrm{~mol}^{-1}\)

The freezing point of equimolal aqueous solution will be highest for (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}^{+} \mathrm{H}_{3} \mathrm{Cl}^{-}\)(aniline hydrochloride) (b) \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) (c) \(\mathrm{La}\left(\mathrm{NO}_{3}\right)_{3}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) (glucose)

A sugar syrup weighing \(214.2 \mathrm{~g}\), contains \(34.2 \mathrm{~g}\) of water. The molal concentration is (a) \(0.55\) (b) \(5.5\) (c) 55 (d) \(0.1\)

When mercuric iodide is added to the aqueous solution of potassium iodide, the (a) freezing point is raised (b) freezing point does not change (c) freezing point is lowered (d) boiling point does not change

The depression in freezing point of \(0.01 \mathrm{M}\) aqueous solution of urea, sodium chloride and sodium sulphate is in the ratio (a) \(1: 1: 1\) (b) \(1: 2: 3\) (c) \(1: 2: 4\) (d) \(2: 2: 3\)

Osmotic pressure of a solution is \(0.0821 \mathrm{~atm}\) at a temperature of \(300 \mathrm{~K}\). The concentration in moles/litre will be (a) \(0.33\) (b) \(0.066\) (c) \(0.3 \times 10^{-2}\) (d) 3

The osmotic pressure of a solution containing \(4.0\) \(\mathrm{g}\) of solute (molar mass 246 ) per litre at \(27^{\circ} \mathrm{C}\) is \(\left(\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)\) (a) \(0.1 \mathrm{~atm}\) (b) \(0.3 \mathrm{~atm}\) (c) \(0.4 \mathrm{~atm}\) (d) \(0.9 \mathrm{~atm}\)

An aqueous solution of sucrose \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\), containing \(34.2 \mathrm{~g} / \mathrm{L}\), has an osmotic pressure of \(2.38\) atmospheres at \(17^{\circ} \mathrm{C}\). For an aqueous solution of glucose \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) to be isotonic with this solution, it would have (a) \(18.0 \mathrm{~g} / \mathrm{L}\) (b) \(16.2 \mathrm{~g} / \mathrm{L}\) (c) \(36.6 \mathrm{~g} / \mathrm{L}\) of glucose (d) \(14.0 \mathrm{~g} / \mathrm{L}\)

A decimolar solution of potassium ferrocyanide is \(50 \%\) dissociated at \(300 \mathrm{~K}\). Calculate the osmotic pressure of the solution. \(\left(\mathrm{R}=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)\) (a) \(0.07389 \mathrm{~atm}\) (b) \(7.389 \mathrm{~atm}\) (c) \(738.89 \mathrm{~atm}\) (d) \(73.89 \mathrm{~atm}\)

A decimolar solution of potassium ferrocyanide is \(50 \%\) dissociated at \(300 \mathrm{~K}\). Calculate the osmotic pressure of the solution. \(\left(\mathrm{R}=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)\) (a) \(0.07389 \mathrm{~atm}\) (b) \(7.389 \mathrm{~atm}\) (c) \(738.89 \mathrm{~atm}\) (d) \(73.89 \mathrm{~atm}\)

\(\mathrm{pH}\) of \(0.1 \mathrm{M}\) monobasic acid solution is found to be \(2 .\) Thus its osmotic pressure at T. K. is (a) \(11.11 \mathrm{ST}\) (b) \(0.11 \mathrm{ST}\) (c) \(0.011 \mathrm{ST}\) (d) \(1.11 \mathrm{ST}\)

The elevation in boiling point for \(13.44 \mathrm{~g}\) of \(\mathrm{CuCl}_{2}\) dissolved in \(1 \mathrm{~kg}\) of water as solvent will be \(\left(\mathrm{K}_{\mathrm{b}}=0.52\right.\) \(\mathrm{kg} / \mathrm{J}\), molar mass of \(\mathrm{CuCl}_{2}=134.4 \mathrm{~g} / \mathrm{mol}\) ) (a) \(0.05\) (b) \(0.10\) (c) \(0.16\) (d) \(0.20\).

A \(0.004 \mathrm{M}\) solution of \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) is isotonic with a \(0.010\) M solution of glucose at same temperature. The apparent degree of dissociation of \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) is (a) \(25 \%\) (b) \(50 \%\) (c) \(75 \%\) (d) \(85 \%\)

What is the freezing point of one litre of an aqueous solution of a non- electrolyte having an osmotic pressure of \(2 \mathrm{~atm}\) at \(300 \mathrm{~K}\). (a) \(273.349 \mathrm{~K}\) (b) \(263.159 \mathrm{~K}\) (c) \(215.569 \mathrm{~K}\) (d) \(272.849 \mathrm{~K}\)

The molality of 1 litre solution of \(93 \% \mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{w} / \mathrm{v})\) having density \(1.84 \mathrm{~g} / \mathrm{mL}\) is (a) \(10.43\) (b) \(1.043\) (c) \(0.1043\) (d) \(100.43\)

The vapour pressure of pure benzene and toluene are 160 and 60 torr respectively. The mole fraction of toluene in vapour phase in contact with equimolar solution of benzene and toluene is (a) \(0.6\) (b) \(0.50\) (c) \(0.27\) (d) \(0.74\)

An aqueous solution of \(6.3 \mathrm{~g}\) oxalic acid dihydrate is made up to \(250 \mathrm{~mL}\). The volume of \(0.1 \mathrm{~N} \mathrm{NaOH}\) required to completely neutralize \(10 \mathrm{~mL}\) of this solution is (a) \(40 \mathrm{~mL}\) (b) \(20 \mathrm{~mL}\) (c) \(10 \mathrm{~mL}\) (d) \(4 \mathrm{~mL}\)

An aqueous solution of \(6.3 \mathrm{~g}\) oxalic acid dihydrate is made up to \(250 \mathrm{~mL}\). The volume of \(0.1 \mathrm{~N} \mathrm{NaOH}\) required to completely neutralize \(10 \mathrm{~mL}\) of this solution is (a) \(40 \mathrm{~mL}\) (b) \(20 \mathrm{~mL}\) (c) \(10 \mathrm{~mL}\) (d) \(4 \mathrm{~mL}\)

The van't Hoff factor for \(0.1 \mathrm{M} \mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\) solution is 2.74. The degree of dissociation is (a) \(91.4 \%\) (b) \(87 \%\) (c) \(100 \%\) (d) \(75 \%\)

The van't Hoff factor for \(0.1 \mathrm{M} \mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\) solution is 2.74. The degree of dissociation is (a) \(91.4 \%\) (b) \(87 \%\) (c) \(100 \%\) (d) \(75 \%\)

A \(0.2\) molal aqueous solution of a weak acid \((\mathrm{HX})\) is \(20 \%\) ionized. The freezing point of this solution is (Given \(\mathrm{K}_{\mathrm{f}}=1.86^{\circ} \mathrm{C} \mathrm{kg} \mathrm{mol}^{-1}\) for water \()\) (a) \(-0.45^{\circ} \mathrm{C}\) (b) \(-0.90^{\circ} \mathrm{C}\) (c) \(-0.21^{\circ} \mathrm{C}\) (d) \(-0.43^{\circ} \mathrm{C}\)

The osmotic pressure of urea solution is \(500 \mathrm{~mm}\) of \(\mathrm{Hg}\) at \(10^{\circ} \mathrm{C}\). If the solution is diluted and temperature is raised to \(25^{\circ} \mathrm{C}\), the osmotic pressure decreases to \(105.3 \mathrm{~mm}\) of \(\mathrm{Hg}\), what is the extent of dilution? (a) 10 times (b) \(2.5\) times (c) 5 times (d) \(7.5\) times

The molality of a \(15 \%(\mathrm{w} / \mathrm{v})\) solution of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) of density \(1.1 \mathrm{~g} / \mathrm{cm}^{3}\) is nearly (a) \(1.3\) (b) \(1.6\) (c) \(1.46\) (d) \(1.86\)

The vapour pressure of a solution of \(5 \mathrm{~g}\) of non electrolyte in \(100 \mathrm{~g}\) of water at a particular temperature is \(2985 \mathrm{Nm}^{-2}\). The vapour pressure of pure water at that temperature is \(3000 \mathrm{Nm}^{-2}\). The molecular weight of the solute is (a) 180 (b) 90 (c) 270 (d) 360

Organic liquids A and B have vapour pressures \(\mathrm{p}_{1}^{0}\) and \(\mathrm{p}_{2}^{\circ}\) as pure liquids at \(80^{\circ} \mathrm{C}\). A mixture of the two liquids behaving ideally and boiling at \(80^{\circ} \mathrm{C}\) has mole fraction of \(\mathrm{A}=0.16\). If \(\left(\mathrm{p}_{2}^{\circ}-\mathrm{p}_{1}^{\circ}\right)=472 \mathrm{~mm}\) of \(\mathrm{Hg}\), what is the value of \(p_{1}^{0}\) (in \(\mathrm{mm} \mathrm{Hg}\) )? (a) \(263.6 \mathrm{~mm}\) (b) \(463.5 \mathrm{~mm}\) (c) \(663.3 \mathrm{~mm}\) (d) \(363.5 \mathrm{~mm}\)

In the freezing point depression experiment, it is observed that (a) at the freezing point the solvent begins to freeze. (b) relative lowering of vapour pressure of solution \((\mathrm{X})\) is more than \((\mathrm{Y})\). (c) the decrease in freezing point of \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}\) (X) in \(\mathrm{C}_{6} \mathrm{H}_{6}\) is lower than that of \(0.1 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}\) (Y) in water. (d) the decrease in freezing point in the two solutions is same.

An aqueous solution of a solute which nerther assoc1ates nor dissociates has a freezing point depression of \(\mathrm{X}^{\circ} \mathrm{C}\). An equimolar solution of a second has a freezing point depression of \(4 \mathrm{X}^{\circ} \mathrm{C}\). The second solution could be a salt of formula (assuming \(100 \%\) dissociation ) (a) \(\mathrm{AB}_{2}\) (b) \(\mathrm{A}_{2} \mathrm{~B}_{2}\) (c) \(\mathrm{A}_{3} \mathrm{~B}\) (d) \(\mathrm{AB}_{3}\)

The amount of dissolved oxygen in 1 litre water in equilibrium with air at 1 atm pressure at \(25^{\circ} \mathrm{C}\) will be (assume that air contains 20 mole \% oxygen, Henry's constant \((\mathrm{kH})\) for oxygen is \(3.04 \times 10^{7} \mathrm{~mm} \mathrm{Hg}\) and density of \(\mathrm{H}_{2} \mathrm{O}\) at \(25^{\circ} \mathrm{C}\) is \(1 \mathrm{~g} / \mathrm{cc}\) ) (a) the mole fraction of \(\mathrm{O}_{2}\) in solution is \(5 \times 10^{-6}\) (b) the mole fraction of \(\mathrm{O}_{2}^{2}\) in solution is \(5 \times 10^{-7}\) (c) the molarity of \(\mathrm{O}_{2}\) in solution is \(2.77 \times 10^{-5} \mathrm{M}\) (d) the molarity of \(\mathrm{O}_{2}\) in solution is \(2.77 \times 10^{4} \mathrm{M}\)

Correct mathematical equations for the Raoult's law are (a) \(\frac{P^{o}-P_{S}}{P_{s}}=\) mole fraction of solvent (b) \(\frac{P^{O_{S}}-P_{S}}{P_{o}}=\) mole fraction of a nonvolatile solute (c) \(P_{s} \propto\) mole fraction of solvent (d) \(P_{s} \propto\) mole fraction of a non volatile solute

For the binary ideal solution having 1 mole of \(\mathrm{A}\) and 2 moles of B at \(298 \mathrm{~K}\) which one is correct? (a) \(\Delta \mathrm{S}_{\operatorname{mix}}=-\mathrm{R} \sum \mathrm{x}_{1} \ln \mathrm{x}_{\mathrm{i}}\) (b) \(\Delta \mathrm{H}_{\operatorname{mix}}=0\) (c) \(\Delta \mathrm{G}_{\operatorname{mix}}=\mathrm{RT} \sum \mathrm{x}_{\mathrm{i}} \ln \mathrm{x}_{\mathrm{i}}\) (d) \(\Delta \mathrm{H}_{\operatorname{mix}}=(+)\) ve

The van't Hoff factor (i), is a measure of association or dissociation. The van't Hoff factor for \(0.1 \mathrm{M}\) aqueous sodium chloride is \(1.87 .\) In magnesium sulphate the ionic interactions (a) Are weaker than that observed in sodium chloride. (b) Are same as that observed in sodium chloride (c) Are stronger than that observed in sodium chloride. (d) Are not responsible for the (i) value.

Mercuric iodide is added to an aqueous solution of potassium iodide. Identify the correct statement(s) (a) Freezing point is raised. (b) Freezing point is lowered. (c) Freezing point and boiling point does not change. (d) Boiling point is raised. (a) 1 and 4 (b) 3 and 4 (c) Only 1 (d) 2 and 4

Mercuric iodide is added to an aqueous solution of potassium iodide. Identify the correct statement(s) (a) Freezing point is raised. (b) Freezing point is lowered. (c) Freezing point and boiling point does not change. (d) Boiling point is raised. (a) 1 and 4 (b) 3 and 4 (c) Only 1 (d) 2 and 4