States of Matter – II

1) With an increase in temperature, the difference between the r.m.s velocity and the average velocity will
a) increase
b) decrease
c) remain same
d) decrease becoming almost zero at a high temperature

2) At what temperature is the K.E of a gas molecule half that of its value at ?

3) At lower temperatures, all gases show
a) negative deviation
b) positive deviation
c) positive and negative deviation
d) none

4) The ratio of most probable velocity (a ), average velocity (n ) and root mean square (u) is

5) In case of hydrogen and helium, the van der Waal’s forces are
a) Strong
b) Very strong
c) Weak
d) Very weak

6) At the same temperature and pressure, which of the following gases will have the highest kinetic energy per mole?
a) Hydrogen
b) Oxygen
c) Methane
d) All have the same

7) The collision frequency (Z) of a gas at a particular pressure
a) decreases with the rise in temperature
b) increases with the rise in temperature
c) decreases initially and thereafter increases
d) is unpredictable

8) The closest distance between the centres of two molecules of a gas taking part in collision is called the
a) Bond length
b) Collision diameter
c) Mean free path
d) None of the above

9) If the mean free path is at one atm pressure then its value at 5 atm pressure is
a) 5 a
d) unpredictable

10) The number of collisions between gas molecules is
a) Independent of pressure
b) Independent of temperature
c) Dependent on temperature
d) Independent of both temperature and pressure

11) If the collision frequency of a gas at 1 atm pressure is Z, then its collision frequency at 0.5 atm is
a) 1.0 Z
b) 0.25 Z
c) 2 Z
d) 0.50 Z

12) The mean free path of a gas molecule is the distance
a) between the two opposite walls of the container
b) which the molecules travel in one second
c) through which a molecule moves between two consecutive collisions
d) none of these

13) The critical temperature of a substance is defined as
a) the temperature above which the substance decomposes
b) the temperature above which a substance can exist only as a gas
c) the melting point of the substance
d) the boiling point of the substance

14) When a compressed gas is allowed to expand through a porous plug at a temperature above its inversion temperature, there is
a) a fall in temperature
b) a rise in temperature
c) neither a fall nor a rise in temperature
d) a fall in temperature first, followed by a rise in temperature

15) The Joule Thomson coefficient is zero at the
a) Inversion temperature
b) Critical temperature
c) Absolute temperature

16) NH3 can be liquefied at ordinary temperatures without the application of pressure. But O2 cannot, because
a) its critical temperature is very high
b) its critical temperature is low
c) its critical temperature is moderate
d) its critical temperature is higher than that of ammonia

17) The gas which can be liquefied under high pressure at 4o C is
a) nitrogen
b) hydrogen
c) oxygen
d) ammonia

18) All gases can be liquefied by
a) Cooling alone
b) Compressing alone
c) Both cooling and compressing
d) None

19) The gas that is heated up by the Joule Thomson effect at ordinary temperatures is

20) Two substances with the same reduced pressure and the same reduced temperature will have the same reduced volume. This is called
b) the law of corresponding states
c) the law of reciprocal proportions
d) the continuity of state

21) A relation between vapour pressure and temperature is known as the
a) Gas equation
b) Clapeyron equation
c) Clausius equation
d) Clausius – Clapeyron equation

22) When an ideal gas undergoes unrestricted expansion
a) cooling occurs because the molecules lie above inversion temperature
b) no cooling occurs as no attractive interactions exist among molecules
c) cooling occurs as molecules collide with each other with loss of energy
d) cooling does not occur as these do work equal to loss in kinetic energy

23) A gas X causes the heating effect when allowed to expand. This is because
a) the gas is a noble gas
b) the inversion temperature of the gas is very low
c) the gas is an ideal gas
d) the boiling point of the gas is very low

24) A gas can be liquefied by pressure alone when its temperature is
a) Higher than its critical temperature
b) Lower than its critical temperature
c) Equal to its critical temperature
d) None

25) Which set of conditions are favourable to liquefy a gas?
a) Low temperature and high pressure
b) High temperature and low pressure
c) Low temperature and low pressure
d) High temperature and high pressure

26) The behaviour of temporary gases like CO2 approaches that of permanent gases like N2, O2, etc. as the temperature goes
a) below the critical temperature
b) above the critical temperature
c) above absolute zero
d) below absolute zero

27) The relationship between Pc, Vc and Tc is

28) The van der Waal’s constant a for NH3 is larger than that for nitrogen because
a) Of intermolecular hydrogen bonding in NH3
b) NH3 is smaller in size
c) N2 is smaller in size
d) van der Waal’s attraction is stronger in N2

29) The constant in equation is maximum for
a) Helium
b) Hydrogen
c) Oxygen
d) Ammonia

30) The cooling caused by the expansion of a compressed gas below its inversion temperature without doing external work is called the
a) Joule Thomson effect
b) Adiabatic demagnetisation
c) Tyndall effect
d) Compton effect

31) Which of the following is a postulate of the kinetic theory?
a) The atom is indivisible
b) Gases combine in a simple ratio
c) There is no influence of gravity on the molecules of a gas
d) None of the above

32) According to the kinetic theory of gases
a) There are intermolecular attractions
b) Molecules have considerable volume
c) there are no intermolecular attractions
d) The velocity of molecules decreases after each collision

33) Who among the following scientists has not done any important work on gases?
a) Boyle
b) Charles
c) Avogadro
d) Faraday

34) In deriving the kinetic gas equation, use is made of the root mean square velocity of the molecules because it is
a) the average velocity of the molecules
b) The most probable velocity of the molecules
c) The square root of the average square velocity of the molecules
d) The most accurate form in which velocity can be used in these calculations

35) Which of the following mixtures of gases does not follow Dalton’s law of partial pressure ?

36) The ratio of the root mean square velocity to the average velocity of gas molecules at a particular temperature is
a) 1.086 : 1
b) 1 : 1.086
c) 2 : 1.086
d) 1.086 : 2

37) The equation explains the behaviour of
a) ideal gases
b) real gases
c) vapour
d) non-real gases

38) When 300 ml of a gas at is cooled to at constant pressure, the final volume is
a) 540 ml
b) 135 ml
c) 270 ml
d) 350 ml

39) A sample of a given mass of a gas at a constant temperature occupies under a pressure of . At the same temperature its volume at a pressure of is

40) A gas of volume 100 cc is kept in a vessel at pressure Pa maintained at temperature . If now the pressure is increased to keeping the temperature constant, then the volume of the gas becomes
a) 10 cc
b) 100 cc
c) 1 cc
d) 1000 cc

41) At what temperature in the Celsius scale will the volume of a certain mass of a gas at will be doubled, the pressure being constant?

42) The average kinetic energy of an ideal gas per molecule in SI units at will be

43) 10 g of a gas at atmospheric pressure is cooled from , the volume remaining constant. Its pressure would become
a) ½ atm
b) 1/273 atm
c) 2 atm
d) 273 atm

44) A certain gas occupies a volume of 250 ml at 700 mm Hg pressure and . What additional pressure is required to reduce the gas volume to 4/5 th of its value at the same temperature?
a) 225 mm Hg
b) 175 mm Hg
c) 150 mm Hg
d) 265 mm Hg

45) At constant temperature , if the pressure increases by 1% the percentage decrease in volume is
a) 1%
b) 100/101%
c) 1/101%
d) 1/100%

46) Pure hydrogen sulphide is stored in a tank of 100 litre capacity at and 2 atm pressure. The mass of the gas will be
a) 34 g
b) 340 g
c) 282. 4 g
d) 28.24 g

47) If the pressure and absolute temperature of 2 litres of are doubled, the volume of will become
a) 2 litres
b) 4 litres
c) 5 litres
d) 7 litres

48) A sample of gas occupies 100 ml at and 740 mm pressure. When its volume is changed to 80 ml at 740 mm pressure, the temperature of the gas will be

49) A weather balloon filled with hydrogen at 1 atm and has a volume of 12000 litres. On ascending it reaches a place where temperature is and the pressure is 0.5 atm. The volume of the balloon now is
a) 24000 litres
b) 20000 litres
c) 10000 litres
d) 12000 litres

50) One litre of a gas weighs 2 g at 300 K and 1 atm pressure. If the pressure becomes 0.75 atm, at which of the following temperatures will one litre of the same gas weigh one gram?
a) 450 K
b) 600K
c) 800K
d) 900K

51) The density of methane at 2.0 atmospheric pressure and is

52) Four molecules of a gas have speeds of 1,2,3,4 respectively. The root mean square velocity is
d) 0 15

53) A gas was compressed to half of its volume at . To what temperature should it be heated so that its volume increases to double its original volume?
b) 303 K
c) 240 K
d) 606 K

54) Equal weights of methane and oxygen are mixed in an empty container at . The fraction of the total pressure exerted by oxygen is
a) 1/3
b) ½
c) 2/3

55) A gaseous mixture contains 56 g of , 44 g and 16 g of . The total pressure of the mixture is 720 mm Hg. The partial pressure of is
a) 180 mm
b) 360 mm
c) 540 mm
d) 720 mm

56) Equal weights of ethane and hydrogen are mixed in an empty container at . The fraction of the total pressure exerted by hydrogen is
a) 1:2
b) 1:1
c) 1:16
d) 15:16

57) A sample of gas is collected over water at at a barometric pressure of 751 mm Hg ( vapour pressure of water at is 21 mm Hg). The partial pressure of gas in the sample collected is
a) 21 mm Hg
b) 751 mm Hg
c) 0.96 atm
d) 1.02 atm

58) 250 ml of at 500 mm pressure and 500 ml of at 250 mm pressure are put together in one litre flask. If the temperature is kept constant, the final pressure of the mixture will be
a) 250 mm
b) 500 mm
c) 750 mm
d) 125 mm

59) A 10 L flask at 300 K contains a gaseous mixture of CO and at a total pressure of 2.0 atm. If 0.2 mol of CO is present, the partial pressure of is ( use R= 0.0821 L atm )
a) 0.49 atm
b) 1.49 atm
c) 1.51 atm
d) 2.49 atm

60) Two grams of hydrogen diffuse from a container in 10 minutes. How many grams of oxygen would diffuse through the same container in the same time under similar conditions?
a) 0.5 g
b) 4 g
c) 6 g
d) 8 g

61) The ratio of the rate of diffusion of a given element to that of helium is 1.4. The molecular weight of the element is
a) 2
b) 4
c) 8
d) 16

62) The time taken for a certain volume of a gas to diffuse through a small hole is 2 minutes. It takes 5.65 minutes for oxygen to diffuse under the similar conditions. The molecular weight of is
a) 8
b) 4
c) 16
d) 48

63) The ratio of the rates of diffusion of and is
b) 1:2:4

64) The molecular weight of a gas that diffuses twice as rapidly as the gas with a molecular weight of 64 is
a) 16
b) 8
c) 64
d) 6.4

65) 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

66) The rate of diffusion of methane at a given temperature is twice that X. The molecular weight of X is
a) 64.0
b) 32.0
c) 40.0
d) 80.0

67) The ratio of diffusion of a gas having molecular weight just double that of nitrogen gas is 56 ml . The rate of diffusion of nitrogen will be

68) Which of the following has the same rate of diffusion as ?

69) Helium and argon are monoatomic gases and their atomic weights are 4 and 40 respectively. Under identical conditions, helium will diffuse through a semipermeable membrane
a) 3.16 times as fast as argon
b) 7.32 times as fast as argon
c) 1.58 times as fast as argon
d) 10 times as fast as argon

70) The ratio of molar heats of vaporisation and boiling point of a liquid is constant This is known as the:
b) Phase rule
d) van’t Hoff rule

71) Ether evaporates faster than water due to the
a) non-polar nature of ether molecules
b) high vapour pressure of ether.
c) Low inter-molecular attractive forces in ether molecules
d) None of these

72) The type of forces in liquid ammonia are expected to be of the
a) dipole-induced dipole type
b) induced dipole-induced dipole type
c) Dipole-dipole type
d) None of these

73) The boiling point of a liquid
a) is the temperature at which its vapour pressure exceeds the atmospheric pressure
b) is the temperature at which its vapour pressure becomes equal to the atmospheric pressure.
c) Remains independent of pressure
d) Decreases with increase of pressure.

74) Which among the following has the highest molar heat of vaporisation?
a) HF
b) HCI
c) HBr
d) HI

75) Which among the following three (I, II, III) are manifestations of surface tension? Choose from the options given:
I) the rise of liquid in a capillary tube
II) the spherical shape of liquid drops
III) the upward movement of water in soil
a) I and II only
b) II and III only
c) I and III only
d) I,II and III

76) The units of surface tension is
b) ergs/cm

77) Generally, liquid drops assume a spherical shape because:
a) a sphere has maximum surface area
b) a sphere has minimum surface area
c) a sphere is symmetrical in shape
d) none of these.

78) @ The surface tension of water at is 72.75 dyne . Its value in the SI system is
d) none of the above

79) Which of the following are surface active? Choose from the options given:
I) cholesterol
II) alcohol
III) soap
a) I and II only
b) II and III only
c) I and III only
d) all three

80) On heating a liquid, its surface tension
a) increases
b) decreases
c) remains same
d) is reduced to zero

81) Water drops stick to a glass surface due to
a) cohesion
b) adhesion
c) flocculation
d) none of these

82) The internal resistance of a liquid to flow is called
a) Fluidity
b) Specific resistance
c) Viscosity
d) Surface tension.

83) Which has the maximum viscosity ?
a) Water
b) Glycol
c) Acetone
d) Ethanol

84) @ Viscosity is
a) A colligative property
b) Independent of temperature
c) Related to boiling point
d) None of the above

85) Poise stands for

86) Which of the following expressions regarding the unit of coefficient of viscosity is not true?

87) In S I system, the unit of coefficient of viscosity is

88) With a rise in temperature, the viscosity of a liquid
a) increases
b) decreases
c) remains constant
d) may increase or decrease.

89) With increasing molecular weight of a liquid, the viscosity
a) decreases
b) increases
c) no effect
d) None of the statements is necessarily correct .

90) The presence of ionic salts in a liquid
a) decreases the viscosity of the liquid
b) increases the viscosity of the liquid
c) does not affect the viscosity of the liquid
d) none of the above is correct.

91) Which one of the following is correct about surface tension (S.T) and viscosity
a) both increase with temperature
b) Both decrease with temperature
d) S.T decreases where as n increases with temperature

92) Metallic liquids contain
a) metal atoms
b) ions and mobile electrons
c) aggregates of metal atoms
d) none of the these

93) Which of the following properties increases with the increase in temperature?
a) Vapour pressure
b) Surface tension
c) Viscosity
d) Both surface tension and fluidity.

94) is an example of a/an
a) ionic liquid
b) hydrogen bonded liquid
c) molecular liquid
d) none of these

95) The rise of a liquid in a capillary tube is due to
a) viscosity
b) diffusion
c) surface tension
d) osmosis

96) The Clausius-Clapeyron equation depicts the
a) effect of temperature on the vapour pressure of a liquid
b) effect of pressure on the boiling point of a liquid
c) effect of temperature on surface tension of liquid
d) none of these.

97) A drop of liquid acquires a spherical shape
a) because of its viscous nature
b) because of capillary action
c) because surface tension tends to minimize the surface area
d) because of all the aforesaid reasons.

98) The vacancy theory of liquids was proposed by
a) H. Eyring and T. Ree
b) Williamson
c) Bragg
d) None.

99) The formation of bubbles in a liquid is due to
a) viscosity
b) inter-molecular forces
c) vapour pressure
d) surface tension.

100) The best potential model to represent attraction and repulsion between the molecules of a liquid is the
a) Sutherland model
b) Lennard-Jones 6-12 potential model
c) Rigid sphere model
d) Beattie Bridgemann model.

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