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STATES OF MATTER 91
Mole fraction of neon = 3 3
2 3 5
Ne
3P 10 6 bar
5
56. (b) P1V1 = P2V2
760 × 500 = P2 × 200.
P2 = 
760 500 1900mm
200 Hg
57. (d) Value of gas constant depends only upon units of
measurement.
58. (a) Given conditions
V1 = 16.4 L, V2 = 5 L
P1 = 1.5 atm, P2 = 4.1 atm
T1 = 273 + 27 = 300 K,
T2 = 273 + 227 = 500 K
Applying gas equation, 1 1 1 1
2 2 2 2
P V n T
P V n T
1 1 1 1
2 2 2 2
n P V T
n P V T
1.5 16.4 500 2
4.1 5 300 1
59. (d) On applying Dalton's law,
Partial pressure of a component
= Mole fraction × Total pressure
Given, mass of N2 = 56 g, mass of O2 = 96 g
Total pressure = 10 atm
n n
2 2
56 96N 2, O 3
28 32
n
x 2
2 n n
2 2
N 2N 0.4,
2 3N O
n
x 2
2 n n
2 2
O 3O 0.6
2 3N O
 PN2 = 0.4 × 10 = 4 atm, PO2 = 0.6 × 10 = 6 atm
60. (d) From the ideal gas equation :
PV nRT
or 
33170 10
8.314 300
PVn
RT
 = 1.27 × 10–3
61. (a) By Dalton’s law of partial pressures, the total pressure
of a mixture of two gases is the sum of the partial
pressures.
62. (b) An ideal gas equation is the combination of Boyle's
law, Charles' law and Avogadro law.
63. (b) According to kinetic theory the gas molecules are in a
state of constant rapid motion in all possible directions
colloiding in a random manner with one another and
with the walls of the container and between two
successive collisions molecules travel in a straight line
path but show haphazard motion due to collisions.
64. (c) Given statement explain the great compressibility of
gases.
65. (b) If there were loss of kinetic energy, the motion of
molecule will stop and gases will settle down.
66. (b) Particles of a gas are always in constant and random
motion. If the particles were at rest and occupy fixed
positions, then a gas would have a fixed shape which
is not observed.
67. (b) If assumption (ii) is correct, the pressure vs volume
graph of experimental data (real gas) and that of
theoretically calculated for Boyle's law (ideal gas)
should coincide.
68. (d) Kinetic theory of gases proves all the given gas laws.
69. (d) Molecules move very fast in all directions in a straight
line by colliding with each other but with different
velocity.
70. (b) At low temperature and high pressure.
71. (a) In van der waals equation ‘b’ is for volume correction
72. (c)
2
aP
V
 (V – b) = RTT; Here 
2
aP
V
 represents
the intermolecular forces.
73. (c) ‘a’ is directly related to forces of attraction. Hence
greater the value of ‘a’, more easily the gas gets
liquified.
74. (b)
(i) At very large molar volume
2 and m m
m
aP P V b V
V
(iii) According to van der Waals equation 'a' and 'b' are
independent of temperature.
75. (a)
2 2
6 -2
2 2; atm dm moln a PVP a
V n
76. (c) Easily liquefiable gases have greater intermolecular
forces which is represented by high value of 'a'. The
greater the value of 'a' more will be liquefiability.
So, the order is Q 1 at high pressure
79. (d) CO2 has highest critical temperature of 304.2 K
80. (d) At low pressure and high temperature: At low pressure
volume correction for 1 mole of a gas in negligible, i.e b
= 0
thus the gas equation becomes
2
aP V RT
V
æ ö÷ç ÷+ =ç ÷ç ÷çè ø
or m
m
PV aZ 1
RT V RT
= = -
At higher pressure, the pressure correction for 1 mole
of gas in negligible i.e 2
a 0
V
=
or (P + 0) (V – b) = RT
or P (Vm – b) = RT
or PVm = RT + Pb
or mPV
Z
RT
=
Pb1
RT
= +
81. (d) In the ideal gas, the intermolecular forces of attraction
are negligible and hence it cannot be liquefied.
82. (d)
83. (d) Above Boyle point, real gases show positive deviation
from ideality and Z values are greater than one.
84. (c)
85. (c) More will be critical temperature easier is the
liquifaction of the gas. Hence correct order will be
He C2H5OH >
CH3OH.
97. (a) Boiling point of water is 100°C whereas evaporation of
water into water vapours occurs at room temperature.
98. (a) As intermolecular forces are least in case of petrol.
Thus, it has highest rate of evaporation.
99. (c) The correct order of viscosity of the given liquids is
dimethyl etherand lowest temperature.
127. (c)
128. (d) According to Boyle’s law at constant temperature,
P
1V or PV = constant
129. (a) Applying Boyle's law P1V1 = P2V2 for both gases
3P400
1000
500
3
200P
3P
1000
6.666600
3
400P
tor200
3
600
3
400
3
200PPPT
130. (c) Percentage of nitrogen in atmosphere is 78% .Partial
pressure of N2 = 0. 78 × 760
131. (d) By Ideal gas equation
RTnVP 11
11 Pn and 22 Pn
2
1
2
1
P
P
n
n
570
170
n
n
2
1 0.30
132. (a) Given weight of empty glass vessel = 50 g
Weight of vessel filled with liquid = 144 g
Weight of liquid = 144 – 50 = 94 g.
Volume of liquid = Mass/density = 94/0.47
= 200 ml = 200 × 10–3 L.
Given, pressure of ideal gas = 760 mm Hg = 1 atm
Temperature = 300 K
R = 0.0821 L atm K–1 mol–1
Mass of ideal gas = 50.5 – 50 = 0.5 g
According to ideal gas equation,
PV = nRT = 
w
RT
M
1 × 200 × 10–3 0.5 0.0821 300
M
–3
0.5 0.0821 300
M 61.575
200 10
133. (d) p1 = 1.5 atm, T1 = 15°C = (15 + 273)K = 288 K
p2 = 1 atm, T2 = 25°C = (25 + 273)K = 298 K
1 1 2 2
1 2
p V p V
T T
1 2 2 2
1 2 1 1
p T V V 1.5 298 1.55
T p V V 288 1
94 STATES OF MATTER
134. (c) Moles of A, (nA) A Ap v 8 12 96
RT RT RT
Moles of B, (nB) B Bp v 8 5 40
RT RT RT
Total pressure × total volume = (nA + nB) × RT
1p (12 8) (96 40)RT
RT
 p = 6.8
Partial pressure of A = p × mole fraction of A
 
96 96 406.8
RT RT
 = 4.8 atm
Partial pressure of B = 6.8 – 4.8 = 2 atm.
135. (d) Number of moles of O2 1
70.6g 2.21 mol
32g mol
Number of moles of Ne 
1
167.5g 8.375 mol
20g mol
Mole fraction of O2 
2.21 0.21
2.21 8.375
Mole fraction of Ne = 1 – 0.21 = 0.79
Partial pressure of a gas = Mole fraction × total pressure
Partial pressure of O2 = 0.21 × 25 = 5.25 bar
Partial pressure of Ne = 0.79 × 25 = 19.75 bar
136. (a) Extent of diffusion H2 > CH4 > SO2 because rate of
diffusion
1
molar mass
Order of partial pressure after diffusion is
2 4 2SO CH Hp p p
137. (a) As the height increases, atmospheric pressure
decreases, so now the volume of the gas increases
and gas tends to become less denser, hence the
concentration of oxygen decreases.
138. (d) The mathematical relationship between pressure and
temperature was given by Gay Lussac's law.
139. (c) Number of moles, temperature and volume are same.
140. (c) Due to small size of these species (H2 and He)
intermolecular interactions (van der Waal forces) are
very low, therefore it is difficult to compress these .
141. (a) Since surface tension depends on the attractive
forces between the molecules, and hydrogen bonding
a special type of dipole-dipole interactions in (b), (c)
and (d) which is stronger than London forces of
attraction in hexane.
142. (c)
143. (a) Force is required to maintain the flow of layer which
is inversely proportional to the area of contact of
layer therefore flow in B is greater than that in A as
the area of contact is greater in A. Also viscosity of
the fluid decreases with increase in temperature
therefore liquid flow increases.
FACT/DEFINITION TYPE QUESTIONS
1. Thermodynamics is not concerned about____.
(a) energy changes involved in a chemical reaction.
(b) the extent to which a chemical reaction proceeds.
(c) the rate at which a reaction proceeds
(d) the feasibility of a chemical reaction.
2. Which of the following statements is not true regarding the
laws of thermodynamics ?
(a) It deal with energy changes of macroscopic systems.
(b) It deal with energy changes of microscopic systems.
(c) It does not depends on the rate at which these energy
transformations are carried out.
(d) It depends on initial and final states of a system
undergoing the change.
3. A……………... in thermodynamics refers to that part of
universe in which observations are made and remaining
universe constitutes the……………...
(a) surroundings, system (b) system, surroundings
(c) system, surroundings (d) system, boundary
4. The universe refers to
(a) only system
(b) only surroundings
(c) both system and surroundings
(d) None of these
5. Which of the following statements is correct?
(a) The presence of reacting species in a covered beaker
is an example of open system.
(b) There is an exchange of energy as well as matter
between the system and the surroundings in a closed
system.
(c) The presence of reactants in a closed vessel made up
of copper is an example of a closed system.
(d) The presence of reactants in a thermos flask or any
other closed insulated vessel is an example of a closed
system.
6. Which of the following is closed system ?
(a) Jet engine
(b) Tea placed in a steel kettle
(c) Pressure cooker
(d) Rocket engine during propulsion
7. An isolated system is that system in which
(a) There is no exchange of energy with the surroundings
(b) There is exchange of mass and energy with the
surroundings
(c) There is no exchange of mass or energy with the
surroundings
(d) There is exchange of mass with the surroundings
8. The state of a thermodynamic system is described by its
measurable or macroscopic (bulk) properties. These are
(a) Pressure and volume
(b) Pressure, volume, temperature and amount
(c) Volume, temperature and amount
(d) Pressure and temperature
9. Which of the following are not state functions ?
(I) q + w (II) q
(III) w (IV) H - TS
(a) (I) and (IV) (b) (II), (III) and (IV)
(c) (I), (II) and (III) (d) (II) and (III)
10. Among the following the state function(s) is (are)
(i) Internal energy
(ii) Irreversible expansion work
(iii) Reversible expansion work
(iv) Molar enthalpy
(a) (ii) and (iii) (b) (i), (ii) and (iii)
(c) (i) and (iv) (d) (i) only
11. Enthalpy change ( H) of a system depends upon its
(a) Initial state
(b) Final state
(c) Both on initial and final state
(d) None of these
12. ………………. is a quantity which represents the total energy
of the system
(a) Internal energy (b) Chemical energy
(c) Electrical energy (d) Mechanical energy
13. Which of the following factors affect the internal energy of
the system ?
(a) Heat passes into or out of the system.
(b) Work is done on or by the system.
(c) Matter enters or leaves the system.
(d) All of the above
THERMODYNAMICS
6
96 THERMODYNAMICS
14. The system that would not allow exchange of heat between
the system and surroundings through its boundary is
considered as
(a) isothermal (b) adiabatic
(c) isobaric (d) isochoric
15. The enthalpy change of a reaction does not depend on
(a) The state of reactants and products
(b) Nature of reactants and products
(c) Different intermediate reactions
(d) Initial and final enthalpy change of a reaction.
16. The q is ……………. when heat is transferred from the
surroundings to the system and q is………………………..
When heat is transferred from system to the surroundings.
(a) positive , negative (b) negative , positive
(c) high, low (d) low, high
17. Adiabatic expansions of an ideal gas is accompanied by
(a) decrease in E
(b) increase in temperature
(c) decrease in S
(d) no change in any one of the above properties
18. Which of the following statements is incorrect?
(a) q is a path dependent function.
(b) H is a state function.
(c) Both H and q are state functions.
(d) Both (a) and (b)
19. Figure below is showing that one mole of an ideal gas is
fitted with a frictionless piston. Total volume of the gas is
Vi and pressure of the gas inside is p. If external pressure is
pex which is greater than p is applied, piston is moved inward
till the pressure inside becomes equal to pex.
Area = p Vex
Vf Vi Volume, V
pex
pex
pex
l
Pr
es
su
re
, p
What does the shaded area represents in the figure ?
(a) Work done (b) Pressure change
(c) Volume change (d) Temperature change
20. When 1 mol of a gas is heated at constant volume,
temperature is raised from 298 to 308 K. If heat supplied to
the gas is 500 J, then which statement is correct ?
(a) q = w = 500 J, U = 0 (b) q = U = 500 J, w = 0
(c) q = –w = 500 J, U = 0 (d) U = 0, q = w = –500 J
21. The work done during the expansion of a gas from a volume
of 4 dm3 to 6 dm3 against a constant external pressure of 3
atm is (1 L atm = 101.32 J)
(a)– 6 J (b) – 608 J
(c) + 304 J (d) – 304 J
22. Which of the following statements/relationships is not
correct in thermodynamic changes ?
(a) U = (isothermal reversible expansion of a gas)
(b) w = – nRT ln 2
1
V
V
 (isothermal reversible expansion of
an ideal gas)
(c) w = nRT ln 2
1
V
V
 (isothermal reversible expansion of an
ideal gas)
(d) For a system of constant volume heat involved directly
changes to internal energy.
23. An ideal gas expands in volume from 1×10–3 to 1 × 10–2 m3
at 300 K against a constant pressure of 1×105 Nm–2. The
work done is
(a) 270 kJ (b) – 900 kJ
(c) – 900 J (d) 900 kJ
24. The difference between H and U is usually significant
for systems consisting of
(a) only solids (b) only liquids
(c) both solids and liquids (d) only gases
25. If a reaction involves only solids and liquids which of the
following is true ?
(a) H E (d) H = E + RT n
26. During isothermal expansion of an ideal gas, its
(a) internal energy increases
(b) enthalpy decreases
(c) enthalpy remains unaffected
(d) enthalpy reduces to zero.
27. Assume each reaction is carried out in an open container.
For which reaction will H = E ?
(a) C(s) + 2H2O (g) 2H2 (g) + CO2 (g)
(b) PCl5 (g) PCl3 (g) + Cl2 (g)
(c) 2CO (g) + O2 (g) 2CO2 (g)
(d) H2 (g) + Br2 (g) 2 HBr (g)
28. For the reaction )g(CO)g(O
2
1)g(CO 22
Which one of the statement is correct at constant T and P ?
(a) EH
(b) EH
(c) EH
(d) H is independent of physical state of the reactants
THERMODYNAMICS 97
29. For a reaction in which all reactants and products are liquids,
which one of the following equations is most applicable ?
(a) Hone mole of butane, 2658 kJ
of heat is released. The thermochemical reaction for above
change is
(a) 2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l)
cH = –2658.0 kJ mol–1
(b) C4H10(g) +
13
2
O2(g) 4CO2(g) + 5H2O (g)
cH = –1329.0 kJ mol–1
(c) C4H10(g) +
13
2
O2(g) 4CO2(g) + 5H2O (l)
cH = –2658.0 kJ mol–1
(d) C4H10(g) +
13
2
O2 (g) 4CO2(g) +5H2O (l)
cH = + 2658.0 kJ mol–1
59. Given that heat of neutralisation of strong acid and strong
base is – 57.1 kJ. The heat produced when 0.25 mole of HCl
is neutralised with 0.25 mole of NaOH in aqueous solution
is :
(a) 14.275 kJ (b) 57.1 kJ
(c) 22.5 kJ (d) 28.6 kJ
60. For most of the ionic compounds, solH is …………and
the dissociation process is…………….
(a) positive ,exothermic (b) negative, exothermic
(c) positive, endothermic (d) negative,endothermic
THERMODYNAMICS 99
61. Pick out the wrong statement
(a) The standard free energy of formation of all elements
is zero
(b) A process accompanied by decrease in entropy is
spontaneous under certain conditions
(c) The entropy of a perfectly crystalline substance at
absolute zero is zero
(d) A process that leads to increase in free energy will be
spontaneous
62. Identify the correct statement for change of Gibbs energy
for a system ( Gsystem) at constant temperature and
pressure
(a) If Gsystem = 0, the system has attained equilibrium
(b) If Gsystem = 0, the system is still moving in a particular
direction
(c) If Gsystem 0, the process is not spontaneous
63. Identify the correct statement regarding a spontaneous
process:
(a) Lowering of energy in the process is the only criterion
for spontaneity.
(b) For a spontaneous process in an isolated system, the
change in entropy is positive.
(c) Endothermic processes are never spontaneous.
(d) Exothermic processes are always spontaneous.
64. A chemical reaction will be spontaneous if it is accompanied
by a decrease of
(a) entropy of the system.
(b) enthalpy of the system.
(c) internal energy of the system.
(d) free energy of the system.
65. In which of the following entropy decreases?
(a) Crystallization of sucrose solution
(b) Rusting of iron
(c) Melting of ice
(d) Vaporization of camphor
66. A spontaneous reaction is impossible if
(a) both H and S are negative
(b) both H and S are positive
(c) H is negative and S is positive
(d) H is positive and S is negative
67. For the gas phase reaction,
PCl5(g) PCl3(g) + Cl2(g)
which of the following conditions are correct ?
(a) H = 0 and S 0 and S > 0
(c) H 0 and S 0, S > 0 (b) H 0
(c) H > 0, S = 0 (d) H 0, S > 0 and G 0 and G 0, S > 0 and G = 0
76. Choose the reaction with negative S value.
(a) 2NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g)
(b) Cl2(g) 2Cl(g)
(c) 2SO2(g) + O2(g) 2SO3(g)
(d) 2KClO3(s) 2KCl(s) + 3O2(g)