Chapter 10

The Henry's law constant for the solubility of \(\mathrm{N}_{2}\) gas in water at \(298 \mathrm{~K}\) is \(1.0 \times 10^{5} \mathrm{~atm} .\) The mole fraction of \(\mathrm{N}_{2}\) in air is \(0.8 .\) The number of moles of \(\mathrm{N}_{2}\) from air dissolved in 10 moles of water at \(298 \mathrm{~K}\) and 5 atm pressure is (a) \(4.0 \times 10^{-4}\) (b) \(4.0 \times 10^{-5}\) (c) \(5.0 \times 10^{-4}\) (d) \(5.0 \times 10^{-5}\)

Which of the following statement is correct regarding the solubility of gas in water? (a) Solubility increases with the increase in temperature. (b) A more polar gas will be less soluble. (c) Solubility increases with the increase in pressure. (d) Solubility is always endothermic process.

Henry's law constant for \(\mathrm{CO}_{2}\) in water is \(1.6 \times 10^{8} \mathrm{~Pa}\) at \(298 \mathrm{~K}\). The quantity of \(\mathrm{CO}_{2}\) in \(500 \mathrm{~g}\) of soda water when packed under \(3.2\) bar pressure at \(298 \mathrm{~K}\), is (a) \(2.44 \mathrm{~g}\) (b) \(24.4 \mathrm{~g}\) (c) \(0.244 \mathrm{~g}\) (d) \(0.61 \mathrm{~g}\)

Liquids \(\mathrm{A}\) and \(\mathrm{B}\) form an ideal solution. The plot of \(\frac{1}{X_{\mathrm{A}}}\) ( \(Y\) -axis) versus \(\frac{1}{Y_{\mathrm{A}}}\) \(\left(X\right.\) -axis) \(\left(\right.\) where \(X_{\mathrm{A}}\) and \(Y_{\mathrm{A}}\) are the mole fractions of A in liquid and vapour phases at equilibrium, respectively) is linear whose slope and intercept, respectively, are given as (a) \(\frac{P_{\Lambda}^{o}}{P_{\mathrm{B}}^{\circ}}, \frac{\left(P_{\mathrm{A}}^{0}-P_{\mathrm{B}}^{\circ}\right)}{P_{\mathrm{B}}^{\circ}}\) (b) \(\frac{P_{\mathrm{A}}^{\circ}}{P_{\mathrm{B}}^{\circ}}, \frac{\left(P_{\mathrm{B}}^{0}-P_{\mathrm{A}}^{\circ}\right)}{P_{\mathrm{B}}^{\circ}}\) (c) \(\frac{P_{\mathrm{B}}^{\circ}}{P_{\mathrm{A}}^{\circ}}, \frac{\left(P_{\mathrm{A}}^{\mathrm{o}}-P_{\mathrm{B}}^{\circ}\right)}{P_{\mathrm{B}}^{\circ}}\) (d) \(\frac{P_{\mathrm{B}}^{\circ}}{P_{\mathrm{A}}^{\circ}}, \frac{\left(P_{\mathrm{B}}^{0}-P_{\mathrm{A}}^{\circ}\right)}{P_{\mathrm{B}}^{\circ}}\)

On increasing the altitude at constant temperature, vapour pressure of a liquid (a) increases (b) decreases (c) remains the same (d) depends upon climate

A mixture contains \(1 \mathrm{~mole}\) of volatile liquid \(\mathrm{A}\left(P_{\mathrm{A}}^{\circ}=100 \mathrm{~mm} \mathrm{Hg}\right)\) and \(3 \mathrm{moles}\) of volatile liquid \(\mathrm{B}\left(P_{\mathrm{B}}^{\circ}=80 \mathrm{~mm} \mathrm{Hg}\right)\). If the solution behaves ideally, the total vapour pressure of the distillate is (a) \(85 \mathrm{~mm} \mathrm{Hg}\) (b) \(85.88 \mathrm{~mm} \mathrm{Hg}\) (c) \(90 \mathrm{~mm} \mathrm{Hg}\) (d) \(92 \mathrm{~mm} \mathrm{Hg}\)

Which of the following is not a characteristic property of the polar liquids? (a) They have high boiling points. (b) They have high heat of vaporization. (c) They have low viscosity. (d) They have low vapour pressure.

A liquid mixture of ' \(\mathrm{A}\) ' and 'B' (assume ideal solution) is placed in a cylinder and piston arrangement. The piston is slowly pulled out isothermally so that the volume of liquid decreases and that of the vapour increases. At the instant when the quantity of the liquid still remaining is negligibly small, the mole fraction of 'A' in the vapour is \(0.4\). If \(P_{\mathrm{A}}^{\circ}=0.4 \mathrm{~atm}\), \(P_{\mathrm{B}}^{\circ}=1.2 \mathrm{~atm}\) at this temperature, the total pressure at which the liquid has almost evaporated, is (a) \(0.667\) atm (b) \(1.5 \mathrm{~atm}\) (c) \(0.8 \mathrm{~atm}\) (d) \(0.545 \mathrm{~atm}\)

Vapour pressure of the liquid (a) increases with increase in temperature. (b) decreases with increase in temperature. (c) is independent of temperature. (d) either increases or decreases with the increase in temperature, depending on the nature of liquid.

Which of the following behaviour is true about the ideal binary liquid solution of liquids 'A' and ' \(B\) ', if \(P_{A}^{\circ}

For an ideal solution of \(\mathrm{A}\) and \(\mathrm{B}, Y_{\mathrm{A}}\) is the mole fraction of \(\mathrm{A}\) in the vapour phase at equilibrium. Which of the following plot should be linear? (a) \(P_{\text {toul }}\) vs \(Y_{\mathrm{A}}\) (b) \(P_{\text {total }} v s Y_{\mathrm{B}}\) (c) \(\frac{1}{P_{\text {total }}}\) vs \(Y_{\mathrm{A}}\) (d) \(\frac{1}{P_{\text {total }}} v s \frac{1}{Y_{\mathrm{A}}}\)

A liquid solvent is in equilibrium with its vapour. When a non-volatile solute is added to this liquid, the instant effect is the rate at which the solvent molecules leaves the (a) vapour phase, decreases. (b) vapour phase, increases. (c) solution, increases. (d) solution, decreases.

The vapour pressure of a solution of a non-volatile, non-electrolyte solute in a solvent is \(95 \%\) of the vapour pressure of the pure solvent at the same temperature. If the molecular mass of the solvent is \(0.3\) times that of solute, the mass ratio of solvent and solute is (a) \(3: 20\) (b) \(57: 10\) (c) \(1: 5\) (d) \(4: 1\)

Heptane and octane form ideal solution. At \(373 \mathrm{~K}\), the vapour pressures of the pure liquids are \(106 \mathrm{kPa}\) and \(46 \mathrm{kPa}\), respectively. What will be the vapour pressure, in bar, of a mixture of \(30.0 \mathrm{~g}\) of heptane and \(34.2 \mathrm{~g}\) of octane? (a) 76 bar (b) 152 bar (c) \(1.52\) bar (d) \(0.76\) bar

The vapour pressure of a solven decreased by \(10 \mathrm{~mm}\) of \(\mathrm{Hg}\) when a non volatile solute was added to the solvent The mole fraction of solute in th solution is \(0.2 .\) What would be the mol fraction of solvent if decrease in vapou pressure is \(20 \mathrm{~mm}\) of \(\mathrm{Hg}\) ? (a) \(0.8\) (b) \(0.6\) (c) \(0.4\) (d) \(0.7\)

Benzene and toluene form an ideal solution. The vapour pressures of benzene and toluene are \(75 \mathrm{~mm}\) and \(25 \mathrm{~mm}\), respectively, at \(20^{\circ} \mathrm{C}\). If the mole fractions of benzene and toluene in vapour are \(0.75\) and \(0.25\), respectively, the vapour pressure of the ideal solution is (a) \(62.5 \mathrm{~mm}\) (b) \(50 \mathrm{~mm}\) (c) \(30 \mathrm{~mm}\) (d) \(40 \mathrm{~mm}\)

Vapour pressure of a solution of \(5 \mathrm{~g}\) of non-electrolyte in \(100 \mathrm{~g}\) of water at \(\mathrm{a}\) particular temperature is \(2985 \mathrm{~N} / \mathrm{m}^{2}\) If the vapour pressure of pure water at this temperature is \(3000 \mathrm{~N} / \mathrm{m}^{2}\), the molecular mass of the solute is (a) 60 (b) 120 (c) 180 (d) 360

For which of the following pair, the heat of mixing, \(\Delta H_{\text {mix }}\), is approximately zero? (a) \(\mathrm{CH}_{3} \mathrm{COOCH}_{3}+\mathrm{CHCl}_{3}\) (b) \(\mathrm{CH}_{3} \mathrm{COOH}+\mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\mathrm{CH}_{3} \mathrm{O} \mathrm{H}\) (d) \(\mathrm{CH}_{3} \mathrm{COCH}_{3}+\mathrm{C}_{6} \mathrm{H}_{6}\)

The vapour pressure of pure benzene at a certain temperature is \(0.85\) bar. A \(\begin{array}{ll}\text { non-volatile, } & \text { non-electrolyte } & \text { solid }\end{array}\) weighing \(0.5 \mathrm{~g}\) is added to \(39.0 \mathrm{~g}\) of benzene. The vapour pressure of the solution then is \(0.845\) bar. Molar mass of the solid substance is (a) \(169 \mathrm{~g} / \mathrm{mol}\) (b) \(170 \mathrm{~g} / \mathrm{mol}\) (c) \(85 \mathrm{~g} / \mathrm{mol}\) (d) \(39 \mathrm{~g} / \mathrm{mol}\)

The vapour pressure of water is \(12.3 \mathrm{kPa}\) at \(300 \mathrm{~K}\). What is the vapour pressure of 1 molal aqueous solution of a nonvolatile solute at \(300 \mathrm{~K}\) ? (a) \(1.208 \mathrm{kPa}\) (b) \(12.08 \mathrm{kPa}\) (c) \(2.08 \mathrm{kPa}\) (d) \(1208 \mathrm{kPa}\)

The vapour pressure of a solution of two liquids, \(\mathrm{A}\left(P^{\circ}=80 \mathrm{~mm}, X=0.4\right)\) and \(\mathrm{B}\left(P^{\circ}=120 \mathrm{~mm}, X=0.6\right)\) is found to be \(100 \mathrm{~mm}\). It shows that the solution exhibits (a) negative deviation from ideal behaviour. \(\begin{array}{lll}\text { (b) positive } & \text { deviation } & \text { from } & \text { ideal }\end{array}\) behaviour. (c) ideal behaviour. (d) positive deviation at lower concentration

When \(25 \mathrm{ml}\) of \(\mathrm{CCl}_{4}\) and \(25 \mathrm{ml}\) of toluene is mixed, the total volume of the solution will be (a) \(50 \mathrm{~m} /\) (b) \(>50 \mathrm{ml}\) (c) \(<50 \mathrm{ml}\) (d) Indefinite

The immiscible liquid system containing aniline-water boils at \(98^{\circ} \mathrm{C}\) under a pressure of \(760 \mathrm{~mm}\). At this temperature, the vapour pressure of water is \(700 \mathrm{~mm}\). If aniline is distilled in steam at \(98^{\circ} \mathrm{C}\), what per cent of total weight of the distillate will be aniline? (a) \(7.89\) (b) \(8.57\) (c) \(30.7\) (d) \(44.3\)

4A quantity of \(10 \mathrm{~g}\) of solute 'A' and \(20 \mathrm{~g}\) of solute ' \(\mathrm{B}\) ' is dissolved in \(500 \mathrm{~m}\) l water. The solution is isotonic with the solution obtained by dissolving \(6.67 \mathrm{~g}\) of ' \(\mathrm{A}\) ' and \(30 \mathrm{~g}\) of ' \(\mathrm{B}\) ' in \(500 \mathrm{ml}\) water at the same temperature. The ratio of molar masses, \(M_{A}: M_{\mathrm{B}}\), is (a) \(1: 1\) (b) \(3: 1\) (c) \(1: 3\) (d) \(2: 3\)

Which of the following can be separated into its pure components by fractional distillation? (a) \(\mathrm{C}_{6} \mathrm{H}_{6}+\mathrm{C}_{7} \mathrm{H}_{\mathrm{s}}\) (b) \(\mathrm{H}, \mathrm{O}+\mathrm{HCl}\) (c) \(\mathrm{H}_{2} \mathrm{O}+\mathrm{HNO}_{3}\) (d) \(\mathrm{H}_{2} \mathrm{O}+\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\)

Equal volumes of \(M / 20\) glucose solution at \(300 \mathrm{~K}\) and \(M / 20\) sucrose solution at \(300 \mathrm{~K}\) are mixed without change in temperature. If the osmotic pressure of glucose solution, sucrose solution and the mixture of two solutions are \(\pi_{1}, \pi_{2}\) and \(\pi_{3}\) respectively, then (a) \(\pi_{1}=\pi_{2}=\pi_{3}\) (b) \(\pi_{1}>\pi_{2}>\pi_{3}\) (c) \(\pi_{1}<\pi_{2}<\pi_{3}\) (d) \(\pi_{1}=\pi_{2}<\pi_{3}\)

Pure water boils at \(373 \mathrm{~K}\) and nitric acid at \(359 \mathrm{~K}\). The azeotropic mixture of water and nitric acid boils at \(393.5 \mathrm{~K}\). On distillation of the azeotropic mixture, (a) pure nitric acid will distil over first. (b) pure water will distil over first. (c) one of them will distil over with small amount of the other. (d) both of them will distil over in the same composition as they are in the mixture.

Based upon the technique of reverse osmosis, the approximate minimum pressure required to desalinate sea water containing \(2.5 \%\) (w/v) \(\mathrm{NaCl}\) at \(27^{\circ} \mathrm{C}\) should be (a) \(10.5 \mathrm{~atm}\) (b) \(21 \mathrm{~atm}\) (c) \(2.1 \mathrm{~atm}\) (d) \(1.05\) atm

A liquid is in equilibrium with its vapour at its boiling point. On average, the molecules in the two phases have equal (a) potential energy (b) intermolecular force (c) kinetic energy (d) total energy

The boiling point of a \(2 \%(\mathrm{w} / \mathrm{w})\) aqueous solution of a non-volatile, non-electrolyte solute is \(0.102^{\circ} \mathrm{C}\) higher than that of pure water. If \(K_{b}\) for water is \(0.52 \mathrm{~K}-\mathrm{kg} / \mathrm{mol}\), the molecular mass of the solute is (a) 180 (b) 102 (c) 40 (d) 104

The vapour pressure of a solution of non-volatile solute is (a) less than that of solvent (b) equal to that of solvent (c) more than that of solvent (d) equal to or more than that of solvent

The boiling point of pure benzene is \(353.23 \mathrm{~K}\). When \(1.80 \mathrm{~g}\) of a non-volatile solute was dissolved in \(90 \mathrm{~g}\) of benzene, the boiling point is raised to \(354.11 \mathrm{~K}\). Calculate the molar mass of the solute. \(K_{\mathrm{b}}\) for benzene is \(2.53 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\). (a) \(85 \mathrm{~g} \mathrm{~mol}^{-1}\) (b) \(57.5 \mathrm{~g} \mathrm{~mol}^{-1}\) (c) \(23 \mathrm{~g} \mathrm{~mol}^{-1}\) (d) \(38.4 \mathrm{~g} \mathrm{~mol}^{-1}\)

The mass of a non-volatile solute (molecular mass \(=40\) ) which should be dissolved in \(114 \mathrm{~g}\) octane to reduce its vapour pressure to \(80 \%\) is (a) \(8 \mathrm{~g}\) (b) \(12 \mathrm{~g}\) (c) \(4 \mathrm{~g}\) (d) \(10 \mathrm{~g}\)

What is the boiling point of a solution of \(1.00 \mathrm{~g}\) of naphthalene dissolved in \(94.0 \mathrm{~g}\) of toluene? The normal boiling point of toluene is \(110.75^{\circ} \mathrm{C}\) and \(K_{\mathrm{x}, \mathrm{b}}=32.0 \mathrm{~K}\) for toluene. (a) \(110.95^{\circ} \mathrm{C}\) (b) \(111.0^{\circ} \mathrm{C}\) (c) \(113.41^{\circ} \mathrm{C}\) (d) \(110.75^{\circ} \mathrm{C}\)

An ideal solution is obtained by dissolving \(n\) moles of non-volatile, non- electrolyte solute in \(N\) moles of solvent. If the vapour pressure of solution is \(P\) and the vapour pressure of pure solvent is ' \(P^{a}\), then (a) \(\frac{P^{\circ}-P}{P}=\frac{n}{N}\) (b) \(\frac{P^{\circ}-P}{P^{\circ}}=\frac{n}{N}\) (c) \(\frac{P^{o}-P}{P^{\circ}}=\frac{N}{n}\) (d) \(\frac{P^{\circ}-P}{P}=\frac{N}{n}\)

The vapour pressure of an aqueous solution is found to be 750 torr at a temperature, \(T\), and the same solution shows an elevation in boiling point equal to \(1.04 \mathrm{~K}\). If \(T\) is the boiling point of pure water, then the atmospheric pressure should be \(\left(K_{\mathrm{b}}\right.\) of water \(\left.=0.52 \mathrm{~K}-\mathrm{kg} / \mathrm{mol}\right)\) (a) 760 torr (b) 777 torr (c) 746 torr (d) 750 torr

An ideal solution was obtained by mixing methanol and ethanol. If the partial vapour pressures of methanol and ethanol are \(2.8\) and \(4.2 \mathrm{kPa}\) respectively, the mole fraction of methanol in the vapour at equilibrium is (a) \(0.67\) (b) \(0.4\) (c) \(0.6\) (d) \(0.33\)

The molar mass of substance which forms \(7.0 \%\) (by mass) solution in water which freezes at \(-0.93^{\circ} \mathrm{C}\). The cryoscopic constant of water is \(1.86^{\circ} \mathrm{C} \mathrm{kg} \mathrm{mol}^{-1}\). (a) \(140 \mathrm{~g} \mathrm{~mol}^{-1}\) (b) \(150.5 \mathrm{~g} \mathrm{~mol}^{-1}\) (c) \(160 \mathrm{~g} \mathrm{~mol}^{-1}\) (d) \(155 \mathrm{~g} \mathrm{~mol}^{-1}\)

The approximate molality of ethylene glycol \(\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\right)\) in an aqueous solution which freezes at a temperature no higher than \(-15^{\circ} \mathrm{C}\) is \(\left(k_{\mathrm{f}}\right.\) of water \(=1.86^{\circ} \mathrm{C}\) \(\mathrm{kg} \mathrm{mol}^{-1}\) ) (a) \(8.06 \mathrm{~m}\) (b) \(0.806 \mathrm{~m}\) (c) \(0.145 \mathrm{~m}\) (d) \(1.5 \mathrm{~m}\)

Which serves best as a semipermeable membrane? (a) copper ferrocyanide (b) vegetable membrane (c) animal membrane (d) cellophane

After removing the hard shell of an egg by dissolving in dilute \(\mathrm{HCl}\), a semipermeable membrane can be visible. If such an egg is kept in a saturated solution of common salt, the size of egg will (a) shrink (b) grow (c) remain unchanged (d) first shrink, then grow

The process of getting fresh water from sea water is known as (a) osmosis (b) filtration (c) pressure distillation (d) reverse osmosis

The boiling point and freezing point of a solvent 'A' are \(90.0^{\circ} \mathrm{C}\) and \(3.5^{\circ} \mathrm{C}\), respectively. \(K_{\mathrm{f}}\) and \(K_{\mathrm{b}}\) values of the solvent are \(17.5\) and \(5.0 \mathrm{~K}-\mathrm{kg} / \mathrm{mol}\), respectively. What is the boiling point of a solution of 'B' (non-volatile, nonelectrolyte solute) in 'A', if the solution freezes at \(2.8^{\circ} \mathrm{C} ?\) (a) \(90.0^{\circ} \mathrm{C}\) (b) \(89.8^{\circ} \mathrm{C}\) (c) \(90.2^{\circ} \mathrm{C}\) (d) \(90.7^{\circ} \mathrm{C}\)

Blood is isotonic with (a) \(0.9 \%(\mathrm{w} / \mathrm{v})-\mathrm{NaCl}\) solution (b) \(0.9 \mathrm{M}-\mathrm{NaCl}\) solution (c) \(0.9 \mathrm{M}-\mathrm{NaCl}\) solution (d) \(9.0 \%(\mathrm{w} / \mathrm{v})-\mathrm{NaCl}\) solution

The solution containing \(4.0 \mathrm{~g}\) of \(\mathrm{PVC}\) in \(1 \mathrm{~L}\) of dioxane was found to have osmotic pressure of \(0.006\) atm at \(300 \mathrm{~K}\). The molecular mass of the polymer PVC is (a) 16,420 (b) 1642 (c) \(1,64,200\) (d) 4105

A semi-permeable membrane separates a solution that is \(0.012 \mathrm{M}\) in glucose from one that is \(0.250 \mathrm{M}\) in glucose. \(\mathrm{On}\) which of these solutions must pressure be applied to prevent a net flow of water through the membrane? (a) On the \(0.012 \mathrm{M}\) solution (b) On the \(0.250 \mathrm{M}\) solution (c) Equal pressure on both the solutions (d) The pressure on \(0.012 \mathrm{M}\) solution should be double the pressure on \(0.250 \mathrm{M}\) solution.

The normal freezing point of nitrobenzene is \(278.82 \mathrm{~K}\). A non- volatile solute is dissolved in it and a solution of molality \(0.25 \mathrm{~m}\) is prepared. If the observed freezing point of the solution is \(276.82 \mathrm{~K}, K_{\ell}\) of nitrobenzene is (a) \(6 \mathrm{~K}-\mathrm{kg} \mathrm{mol}^{-1}\) (b) \(8 \mathrm{~K}-\mathrm{kg} \mathrm{mol}^{-1}\) (c) \(7 \mathrm{~K}-\mathrm{kg} \mathrm{mol}^{-1}\) (d) \(5 \mathrm{~K}-\mathrm{kg} \mathrm{mol}^{-1}\)

If \(0.1\) molar solution of glucose is separated from \(0.1\) molar solution of cane sugar by a semipermeable membrane, then which one of the following statements is correct? (a) Water will flow from glucose solution into cane sugar solution. (b) Cane sugar will flow across the membrane into glucose solution. (c) Glucose will flow across the membrane into cane sugar solution. (d) There will be no net movement across the semipermeable membrane.

Five per cent solution of a solute \((\mathrm{X})\) is isotonic with \(0.855 \%\) solution of sucrose (molecular weight = 342). What is the molecular mass of solute \((\mathrm{X}) ?\) (a) 200 (b) \(58.482\) (c) 400 (d) 2000

Two elements A and B form compounds having molecular formula \(\mathrm{AB}_{2}\) and \(\mathrm{AB}_{4}\). When dissolved in \(20 \mathrm{~g}\) of \(\mathrm{C}_{6} \mathrm{H}_{6}, 1 \mathrm{~g}\) of \(\mathrm{AB}_{2}\) lowers the freezing point by \(2.55 \mathrm{~K}\), whereas \(1.0 \mathrm{~g}\) of \(\mathrm{AB}_{4}\) lowers it by \(1.7 \mathrm{~K}\). The molar depression constant for benzene is \(5.1 \mathrm{~K}-\mathrm{kg} \mathrm{mol}^{-1}\). The atomic masses of \(\mathrm{A}\) and \(\mathrm{B}\) are (a) 50,25 (b) 50,50 (c) 25,50 (d) 75,25