Chapter 3

Which one of the following statements is wrong for gases? (a) gases do not have a definite shape and volume (b) volume of the gas is equal to volume of container the confining the gas (c) confirmed gas exerts uniform pressure on the walls of its container in all directions (d) mass of gas cannot be determined by weighing a container in which it is enclosed

Which of the following mixture of gases does not obey Dalton's law of partial pressure? (a) \(\mathrm{O}_{2}\) and \(\mathrm{CO}_{2}\) (b) \(\mathrm{N}_{2}\) and \(\mathrm{O}_{2}\) (c) \(\mathrm{Cl}_{2}\) and \(\mathrm{SO}_{2}\) (d) \(\mathrm{NH}_{3}\) and \(\mathrm{HCl}\)

In which of the following pairs, the critical temperature of latter gascous species is higher than the first? (a) \(\mathrm{CO}_{2}, \mathrm{H}_{2}\) (b) \(\mathrm{H}_{2}, \mathrm{NH}_{3}\) (c) \(\mathrm{NH}_{3}, \mathrm{He}\) (d) \(\mathrm{CO}_{2}, \mathrm{He}\)

The dimensions of pressure are same as that of (a) energy (b) energy per unit volume (c) force per unit area (d) force per unit volume

An ideal gas, obeying kinetic theory of gases cannot be liquefied, because (a) its critical temperature is above \(0^{\circ} \mathrm{C}\) (b) its molecules are relatively small in size (c) it solidifies before becoming a liquid (d) forces acting between its molecules are negli-gible.

Which of the following expressions correctly represents the relationship between the average molar kinetic energy, K.E. of \(\mathrm{CO}\) and \(\mathrm{N}_{2}\) molecules at the same temperature? (a) \(\overline{\mathrm{K} . \mathrm{E}_{\mathrm{c}} \mathrm{CO}}<\overline{\mathrm{K} \cdot \mathrm{E}}_{\mathrm{N}_{2}}\) (b) \(\overline{\mathrm{K} . \mathrm{E}}_{\mathrm{CO}}>\overline{\mathrm{K}} \cdot \mathrm{E}_{\mathrm{N}_{2}}\) (c) \(\mathrm{K} \cdot \mathrm{E}_{\mathrm{C} O}=\mathrm{K} \cdot \mathrm{E}_{\mathrm{N}_{2}}\) (d) cannot be predicted unless volumes of the gases are given.

Which of the following law leads us to arrive at the conclusion that 1 g-molecule of each gas at STP occupies a volume of \(22.4 \mathrm{~L}\) ? (a) Dalton's law (b) Law of combining volumes (c) Avogadro's law (d) Boyle's law

\(0.1\) mole of gas absorbs \(41.75 \mathrm{~J}\) of heat, the rise in temperature oecurs \(20^{\circ} \mathrm{C}\), the gas must be (a) triatomic (b) diatomic (c) monoatomic (d) (b) and (c) both

Which pair of the gases diffuses with the same rate at same temperature and pressure? (a) \(\mathrm{CO}\) and \(\mathrm{NO}\) (b) \(\mathrm{NO}_{2}\) and \(\mathrm{CO}_{2}\) (c) \(\mathrm{NH}_{3}\) and \(\mathrm{PH}_{3}\) (d) \(\mathrm{NO}\) and \(\mathrm{C}_{2} \mathrm{H}_{6}\)

Van der Waals real gas, act as an ideal gas, at which condition? (a) high temperature, low pressure (b) low temperature, high pressure (c) high temperature, high pressure (d) low temperature, low pressure

The compressibility factor of an ideal gas is (a) 1 (b) 2 (c) 4 (d) 0

The temperature below which a gas can be made to liquefy by variation in pressure is called its (a) inversion temperature (b) critical temperature (c) neutral temperature (d) curie point

By the ideal gas law the pressure of \(0.60 \mathrm{~mol} \mathrm{NH}_{3}\) gas in a \(3.00\) litre vessel at \(25^{\circ} \mathrm{C}\) is (a) \(48.9 \mathrm{~atm}\) (b) \(4.89 \mathrm{~atm}\) (c) \(0.489 \mathrm{~atm}\) (d) \(489 \mathrm{~atm}\)

At what Centigrade temperature will be the volume of a gas at \(0^{\circ} \mathrm{C}\) double of itself, when pressure remains constant? (a) \(0^{\circ} \mathrm{C}\) (b) \(273^{\circ} \mathrm{C}\) (c) \(273 \mathrm{~K}\) (d) \(546 \mathrm{~K}\)

Pressure of a mixture of \(4 \mathrm{~g}\) of \(\mathrm{O}_{2}\) and \(2 \mathrm{~g}\) of \(\mathrm{H}_{2}\) confined in a bulb of \(1.0 \mathrm{~L}\) capacity at \(0^{\circ} \mathrm{C}\) is (a) \(25.18 \mathrm{~atm}\) (b) \(31.205\) atm (c) \(40.215 \mathrm{~atm}\) (d) \(15.210 \mathrm{~atm}\)

A closed container contains equal number of oxygen and hydrogen molecules at a total pressure of \(740 \mathrm{~mm}\). If oxygen is removed from the system then pressure will (a) become double of \(740 \mathrm{~mm}\) (b) become half of \(740 \mathrm{~mm}\) (c) become \(1 / 9\) of \(740 \mathrm{~mm}\) (d) remain unchanged

The volume occupied by \(9.0 \mathrm{~g}\) of nitrogen gas at \(300 \mathrm{~K}\) and \(750 \mathrm{mmHg}\) pressure is (a) \(5.854\) (b) \(6.7432\) (c) \(8.8462\) (d) \(8.0225\)

What are the conditions under which the relation between volume \((\mathrm{V})\) and number of moles \((\mathrm{n})\) of gas is plotted? ( \(\mathrm{P}=\) pressure; \(\mathrm{T}=\) temperature \()\) (a) constant \(\mathrm{P}\) and \(\mathrm{T}\) (b) constant \(\mathrm{T}\) and \(\mathrm{V}\) (c) constant \(\mathrm{P}\) and \(\mathrm{V}\) (d) constant \(\mathrm{n}\) and \(\mathrm{V}\)

7.5 grams of gas occupy \(5.6\) litres of volume at STP. The gas is ......... (Atomic weight of \(\mathrm{C}, \mathrm{N}\), and \(\mathrm{O}\) are 12,14 and 16 respectively) (a) \(\mathrm{NO}\) (b) \(\mathrm{N}_{2} \mathrm{O}\) (c) \(\mathrm{CO}\) (d) \(\mathrm{CO}_{2}\)

A gas diffuses four times as quickly as oxygen. The molar weight of gas is (a) 2 (b) 4 (c) 8 (d) 16

The density of air is \(0.001293 \mathrm{~g} / \mathrm{cc}\) at STP. Its vapour density is (a) \(0.001293\) (b) \(8.2786\) (c) \(14.48\) (d) \(6.2706\)

At \(27^{\circ} \mathrm{C}\), a closed vessel contains a mixture of equal weights of helium (mol. wt \(=4\) ), methane (mol. wt \(=16\) ) and sulphur dioxide (mol. wt \(=64\) ). The pressure exerted by the mixture is \(210 \mathrm{~mm}\). If the partial pressures of helium, methane and sulphur dioxide are \(\mathrm{P}_{1}, \mathrm{P}_{2}\) and \(\mathrm{P}_{3}\) respectively, which one of the following is correct? (a) \(\mathrm{P}_{3}>\mathrm{P}_{2}>\mathrm{P}_{1}\) (b) \(\mathrm{P}_{1}>\mathrm{P}_{2}>\mathrm{P}_{3}\) (c) \(\mathrm{P}_{1}>\mathrm{P}_{3}>\mathrm{P}_{2}\) (d) \(\mathrm{P}_{2}>\mathrm{P}_{3}>\mathrm{P}_{1}\)

4 grams of an ideal gas occupies \(5.6035\) litres of volume at \(546 \mathrm{~K}\) and 2 atm pressure. What is its molecular weight? (a) 4 (b) 16 (c) 32 (d) 64

The kinetic energy of 4 moles of nitrogen gas at \(127^{\circ} \mathrm{C}\) is ....... Kcals. \(\left(\mathrm{R}=2 \mathrm{cal} \mathrm{mol}^{-1} \mathrm{~K}^{-1}\right)\) (a) 4400 (b) 3200 (c) 4800 (d) 1524

If a gas contains only three molecules that move with velocities of \(100,200,500 \mathrm{~ms}^{-1}\), what is the \(\mathrm{rms}\) velocity of the gas is \(\mathrm{ms}^{-1 ?}\) (a) \(100 \sqrt{8 / 3}\) (b) \(100 \sqrt{30}\) (c) \(100 \vee 0\) (d) \(800 / 3\)

A gaseous mixture contains \(56 \mathrm{~g}\) of \(\mathrm{N}_{2}, 44 \mathrm{~g}\) of \(\mathrm{CO}_{2}\) and \(16 \mathrm{~g}\) of \(\mathrm{CH}_{4}\). The total pressure of mixture is \(720 \mathrm{~mm}\) of \(\mathrm{Hg}\). The partial pressure of methane is (a) \(75 \mathrm{~mm}\) (b) \(160 \mathrm{~mm}\) (c) \(180 \mathrm{~mm}\) (d) \(215 \mathrm{~mm}\)

At \(25^{\circ} \mathrm{C}\) and \(730 \mathrm{~mm}\) pressure, \(380 \mathrm{~mL}\) of dry oxygen was collected. If the temperature is constant, what volume will the oxygen occupy at \(760 \mathrm{~mm}\) pressure? (a) \(365 \mathrm{~mL}\) (b) \(2 \mathrm{~mL}\) (c) \(10 \mathrm{~mL}\) (d) \(20 \mathrm{~mL}\)

The density of an ideal gas is \(0.03 \mathrm{~g} \mathrm{~cm}^{-3}\), Its pressure is \(106 \mathrm{~g} \mathrm{~cm}^{-1} \mathrm{sec}^{-2}\). What is its \(\mathrm{ms}\) velocity (in \(\left.\mathrm{cm} \sec ^{-1}\right)\) ? (a) \(10^{3}\) (b) \(3 \times 10^{4}\) (c) \(10^{2}\) (d) \(10^{4}\)

At a certain pressure, volume of a gas at \(27^{\circ} \mathrm{C}\) is 20 litre. If the pressure and temperature are doubled, its volume will be (a) 20 litre (b) 40 litre (c) \(8.2\) litre (d) \(10.9\) litre

\(\mathrm{A}\) and \(\mathrm{B}\) are ideal gases. The molecular weights of \(\mathrm{A}\) and \(\mathrm{B}\) are in the ratio of \(1: 4\). The pressure of a gas mixture containing equal weights of \(\mathrm{A}\) and \(\mathrm{B}\) is \(\mathrm{P}\) atm. What is the partial pressure (in atm) of B in the mixture? (a) \(\mathrm{P} / 5\) (b) \(\mathrm{P} / 2\) (c) \(\mathrm{P} / 2.5\) (d) \(3 \mathrm{P} / 4\)

A gas has double the average velocity of \(\mathrm{SO}_{2}\) gas at any temperature. The gas may be (a) \(\mathrm{CO}_{2}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (c) \(\mathrm{CH}_{4}\) (d) \(\mathrm{O}_{3}\)

If two moles of ideal gas at \(540 \mathrm{~K}\) has volume \(44.8 \mathrm{~L}\), then its pressure will be (a) \(1 \mathrm{~atm}\) (b) \(2 \mathrm{~atm}\) (c) \(3 \mathrm{~atm}\) (d) \(4 \mathrm{~atm}\)

The densities of two gases are in the ratio of \(1: 16\). The ratio of their rates of diffusion is (a) \(16: 1\) (b) \(4: 1\) (c) \(1: 4\) (d) \(1: 16\)

If pressure of \(2 \mathrm{~mol}\) of an ideal gas at \(546 \mathrm{~K}\) having volume \(44.8\) litre is (a) \(2 \mathrm{~atm}\) (b) \(3 \mathrm{~atm}\) (c) \(4 \mathrm{~atm}\) (d) \(1 \mathrm{~atm}\)

56 g of nitrogen and \(96 \mathrm{~g}\) of oxygen are mixed isothermally and at a total pressure of \(10 \mathrm{~atm}\). The partial pressures of oxygen and nitrogen (in atm) are respectively (a) 4,6 (b) 5,5 (c) 6,4 (d) 8,2

At constant volume and temperature conditions, the rates of diffusion \(\mathrm{D}_{A}\) and \(\mathrm{D}_{\mathrm{B}}\) of gases \(\mathrm{A}\) and \(\mathrm{B}\) having densities \(\rho_{A}\) and \(\rho_{n}\) are related by the expression (a) \(\mathrm{D}_{\mathrm{A}}=\left[\mathrm{D}_{\mathrm{a}} \rho_{\mathrm{A}} / \rho_{\mathrm{h}}\right]^{1 / 2}\) (b) \(\mathrm{D}_{\mathrm{A}}=\left[\mathrm{D}_{\mathrm{B}} \rho_{\mathrm{B}} / \rho_{A}\right]^{1 / 2}\) (c) \(D_{A}=D_{B}\left[\rho_{A} / \rho_{B}\right]^{1 / 2}\) (d) \(\mathrm{D}_{\mathrm{A}}=\mathrm{D}_{\mathrm{B}}\left[\rho_{\mathrm{B}} / \rho_{\mathrm{A}}\right]^{12}\)

The term that accounts for intermolecular force in van der Waals equation for non ideal gas is (a) \(\mathrm{RT}\) (b) \(\mathrm{V}-\mathrm{b}\) (c) \(\left(\mathrm{P}+\alpha \mathrm{V}^{2}\right)\) (d) \((\mathrm{RT})^{-1}\)

A bottle of dry ammonia and a bottle of dry hydrogen chloride connected through a long tube are opened simultaneously at both ends, the white ammonium chloride ring first formed will be (a) at the centre of the tube (b) near the hydrogen chloride bottle (c) near the ammonia bottle (d) throughout the length of the tube

If a gas expands at constant temperature (1) the pressure decreases (2) the kinetic energy of the molecules remains the same (3) the kinetic energy of the molecules decreases (4) the number of molecules of the gas increase (a) 1,2 (b) \(1,2,3\) (c) \(1,2,4\) (d) 2,3

At what temperature the rms velocity of gas shown at \(50^{\circ} \mathrm{c}\) will be doubled? (a) \(626 \mathrm{~K}\) (b) \(1019^{\circ} \mathrm{C}\) (c) \(218 \mathrm{~K}\) (d) \(1019 \mathrm{~K}\)

An ideal gas cannot be liquefied because (a) it solidifies before becoming a liquid (b) forces operative between its molecules are neglgible (c) its molecules are relatively smaller in size (d) its critical temperature is always above \(0^{\circ} \mathrm{C}\)

According to Boyle's law (a) \((\mathrm{dP} / \mathrm{dV})_{\mathrm{T}}=-\mathrm{K} / \mathrm{P}^{2}\) (b) \((\mathrm{dP} / \mathrm{dV})_{\mathrm{T}}=\mathrm{K} / \mathrm{V}\) (c) \((\mathrm{d} \mathrm{V} / \mathrm{dP})_{\mathrm{T}}=-\mathrm{K} / \mathrm{P}^{2}\) (d) \((\mathrm{dV} / \mathrm{dP})_{\mathrm{T}}=-\mathrm{K} / \mathrm{P}\)

The values of van der Waals constant ' \(\alpha\) ' for the gases \(\mathrm{O}_{2}, \mathrm{~N}_{2}, \mathrm{NH}_{3}\) and \(\mathrm{CH}_{4}\) are \(1.360,1.390,4.170\) and \(2.253\) L atm. mol \(^{2}\) respectively. The gas which can most easily be liquefied is (a) \(\mathrm{O}_{2}\) (b) \(\mathrm{N}_{2}\) (c) \(\mathrm{NH}_{3}\) (d) \(\mathrm{CH}_{4}\)

The density of gas \(\mathrm{A}\) is twice of that of \(\mathrm{B}\) and mol. wt. of \(\mathrm{A}\) is half of that of \(\mathrm{B}\). The Ratio of partial pressures of \(P_{A}\) and \(P_{n}\) is (a) \(\frac{1}{4}\) (b) \(\frac{4}{1}\) (c) \(\frac{2}{1}\) (d) \(\frac{1}{2}\)

The ratio of rate of diffusion of helium with respect to methane under similar conditions of constant temperature and pressure (a) \(\underline{2}\) (b) \(0.5\) (c) 16 (d) 4

The density of neon will be highest at (a) STP (b) \(0^{\circ} \mathrm{C}, 2 \mathrm{~atm}\) (c) \(273^{\circ} \mathrm{C}, 1 \mathrm{~atm}\) (d) \(273^{\circ} \mathrm{C}, 2 \mathrm{~atm}\)

At constant volume for a fixed number of a moles of gas, the pressure of the gas increases with the rise in temperature due to (a) increase in average molecular speed (b) increase in rate of collisions (c) increase in molecular attraction (d) increase in mean free path

Four one litre flasks are separately filled with the gases \(\mathrm{O}_{2}, \mathrm{~F}_{2}, \mathrm{CH}_{4}\) and \(\mathrm{CO}_{2}\) under same conditions. The ratio of the number of molecules in these gases are (a) \(2: 2: 4: 3\) (b) \(1: 1: 1: 1\) (c) \(1: 2 ; 3 ; 4\) (d) \(2: 2 ; 3: 4\)

An ideal gas expands according to \(\mathrm{PV}=\) constant. On expansion, the temperature of gas (a) will rise (b) will drop (c) will remain constant (d) cannot be determined because the external pressure is not known

According to the kinetic theory of gases (a) the pressure exerted by a gas is proportional to mean square velocity of the molecules (b) the pressure exerted by the gas is proportional to the root mean square velocity of the molecules (c) the root mean square velocity is inversely proportional to the temperature (d) the mean translational K.E. of the molecule is directly proportional to the absolute temperature.