Thermodynamics- 2 Practice Questions - DPP for NEET

 Page 1


DIRECTIONS (Q.1-Q.19) : There are 19 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 Six moles of an ideal gas performs a cycle shown in figure.
If the temperature 600 , 800 , 2200 = ==
A BC
T KT KT K
and 1200
D
TK = , the work done per cycle is
P
T
A
D
B C
(a) 20 
kJ
(b) 30 
kJ
(c) 40 kJ (d) 60 kJ
Q.2 An ideal gas is taken from point A to the point B , as
shown in the PV - diagram, keeping the temperature
constant. The work done in the process is
P
V
B
A
O
B
P
B
V
A
V
A
P
(a)( )()
A B BA
PP VV -- (b)
1
()()
2
B A BA
PP VV -+
(c)
1
()()
2
BA BA
P P VV -- (d)
1
( )()
2
B A BA
P P VV +-
Page 2


DIRECTIONS (Q.1-Q.19) : There are 19 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 Six moles of an ideal gas performs a cycle shown in figure.
If the temperature 600 , 800 , 2200 = ==
A BC
T KT KT K
and 1200
D
TK = , the work done per cycle is
P
T
A
D
B C
(a) 20 
kJ
(b) 30 
kJ
(c) 40 kJ (d) 60 kJ
Q.2 An ideal gas is taken from point A to the point B , as
shown in the PV - diagram, keeping the temperature
constant. The work done in the process is
P
V
B
A
O
B
P
B
V
A
V
A
P
(a)( )()
A B BA
PP VV -- (b)
1
()()
2
B A BA
PP VV -+
(c)
1
()()
2
BA BA
P P VV -- (d)
1
( )()
2
B A BA
P P VV +-
2
DPP/ P 25
Q.3 In the diagrams (i) to (iv) of variation of volume with
changing pressure is shown. A gas is taken along the path
ABCD. The change in internal energy of the gas will be
(i)
V
P
A
B
C
D
(ii)
V
P
A
B
C D
(iii)
V
P
A
B
C D
(iv)
V
P
A
B
C
D
(a) Positive in all cases (i) to (iv)
(b) Positive in cases (i), (ii) and (iii) but zero in case (iv)
(c) Negative in cases (i), (ii) and (iii) but zero in case (iv)
(d) Zero in all cases
Q.4 A monoatomic ideal gas, initially at temperature T
1
, is
enclosed in a cylinder fitted with a frictionless piston. The
gas is allowed to expand adiabatically to a temperature T
2
by releasing the piston suddenly . If L
1
and L
2
 are the lengths
of the gas column before and after expansion respectively,
then 
12
/ TT is given by
(a)
2/3
1
2
L
L
æö
ç÷
èø
(b)
1
2
L
L
(c)
2
1
L
L
(d)
2/3
2
1
L
L
æö
ç÷
èø
Q.5 A gas mixture consists of 2 moles of oxygen and 4 moles
argon at temperature T. Neglecting all vibrational modes,
the total internal energy of the system is
(a) 4 RT (b) 15 RT (c) 9 RT (d) 11 RT
Q.6 Two Carnot engines A and B are operated in succession.
The first one, A receives heat from a source at 
1
800 TK =
and rejects to sink at 
2
TK . The second engine B receives
heat rejected by the first engine and rejects to another sink
at 
3
300. TK = If the work outputs of two engines are equal,
then the value of T
2
 will be
(a) 100K (b) 300K (c) 550K (d) 700 K
Q.7 A Carnot engine whose low temperature reservoir is at 7°C
has an efficiency of 50%. It is desired to increase the
efficiency to 70%. By how many degrees should the
temperature of the high temperature reservoir be increased
(a) 840K (b) 280 K (c) 560 K (d) 380K
Q.8 An ideal heat engine working between temperature T
1
 and
T
2
 has an efficiency h, the new efficiency of engine if both
the source and sink temperature are doubled, will be
(a)
2
h
(b) h (c)2h (d)3h
Q.9 Efficiency of a Carnot engine is 50% when temperature
of outlet is 500 K. In order to increase efficiency up to
60% keeping temperature of intake the same what will be
temperature of outlet
(a) 200 K (b) 400 K (c) 600 K (d) 800 K
Q.10 A scientist says that the efficiency of his heat engine which
operates at source temperature 120ºC and sink temperature
27ºC is 26%, then
(a) It is impossible
(b) It is possible but less probable
(c) It is quite probable
(d) Data are incomplete
Q.11 The efficiency of Carnot’s engine operating between
reservoirs, maintained at temperatures 27°C and –123°C,
is
(a) 50% (b) 24% (c) 0.75% (d) 0.4%
Q.12The temperature of sink of Carnot engine is 27°C and
Efficiency of engine is 25%. Then temperature of source
is
(a) 227°C (b) 327°C (c) 127°C (d) 27°C
Q.13 In changing the state of thermodynamics from A to B state,
the heat required is Q and the work done by the system is
W. The change in its internal energy is
(a) Q + W (b) Q – W (c) Q (d)
2
QW -
Q.14 The first law of thermodynamics is concerned with the
conservation of
(a) Momentum (b) Energy
(c) Mass (d) Temperature
Q.15A system is given 300 calories of heat and it does 600
joules of work. The internal energy of the system change
in this process is
 (J = 4.18 Joule/cal)
(a) 654 Joule (b) 156.5 Joule
(c) –300 Joule (d) – 528.2 Joule
Page 3


DIRECTIONS (Q.1-Q.19) : There are 19 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 Six moles of an ideal gas performs a cycle shown in figure.
If the temperature 600 , 800 , 2200 = ==
A BC
T KT KT K
and 1200
D
TK = , the work done per cycle is
P
T
A
D
B C
(a) 20 
kJ
(b) 30 
kJ
(c) 40 kJ (d) 60 kJ
Q.2 An ideal gas is taken from point A to the point B , as
shown in the PV - diagram, keeping the temperature
constant. The work done in the process is
P
V
B
A
O
B
P
B
V
A
V
A
P
(a)( )()
A B BA
PP VV -- (b)
1
()()
2
B A BA
PP VV -+
(c)
1
()()
2
BA BA
P P VV -- (d)
1
( )()
2
B A BA
P P VV +-
2
DPP/ P 25
Q.3 In the diagrams (i) to (iv) of variation of volume with
changing pressure is shown. A gas is taken along the path
ABCD. The change in internal energy of the gas will be
(i)
V
P
A
B
C
D
(ii)
V
P
A
B
C D
(iii)
V
P
A
B
C D
(iv)
V
P
A
B
C
D
(a) Positive in all cases (i) to (iv)
(b) Positive in cases (i), (ii) and (iii) but zero in case (iv)
(c) Negative in cases (i), (ii) and (iii) but zero in case (iv)
(d) Zero in all cases
Q.4 A monoatomic ideal gas, initially at temperature T
1
, is
enclosed in a cylinder fitted with a frictionless piston. The
gas is allowed to expand adiabatically to a temperature T
2
by releasing the piston suddenly . If L
1
and L
2
 are the lengths
of the gas column before and after expansion respectively,
then 
12
/ TT is given by
(a)
2/3
1
2
L
L
æö
ç÷
èø
(b)
1
2
L
L
(c)
2
1
L
L
(d)
2/3
2
1
L
L
æö
ç÷
èø
Q.5 A gas mixture consists of 2 moles of oxygen and 4 moles
argon at temperature T. Neglecting all vibrational modes,
the total internal energy of the system is
(a) 4 RT (b) 15 RT (c) 9 RT (d) 11 RT
Q.6 Two Carnot engines A and B are operated in succession.
The first one, A receives heat from a source at 
1
800 TK =
and rejects to sink at 
2
TK . The second engine B receives
heat rejected by the first engine and rejects to another sink
at 
3
300. TK = If the work outputs of two engines are equal,
then the value of T
2
 will be
(a) 100K (b) 300K (c) 550K (d) 700 K
Q.7 A Carnot engine whose low temperature reservoir is at 7°C
has an efficiency of 50%. It is desired to increase the
efficiency to 70%. By how many degrees should the
temperature of the high temperature reservoir be increased
(a) 840K (b) 280 K (c) 560 K (d) 380K
Q.8 An ideal heat engine working between temperature T
1
 and
T
2
 has an efficiency h, the new efficiency of engine if both
the source and sink temperature are doubled, will be
(a)
2
h
(b) h (c)2h (d)3h
Q.9 Efficiency of a Carnot engine is 50% when temperature
of outlet is 500 K. In order to increase efficiency up to
60% keeping temperature of intake the same what will be
temperature of outlet
(a) 200 K (b) 400 K (c) 600 K (d) 800 K
Q.10 A scientist says that the efficiency of his heat engine which
operates at source temperature 120ºC and sink temperature
27ºC is 26%, then
(a) It is impossible
(b) It is possible but less probable
(c) It is quite probable
(d) Data are incomplete
Q.11 The efficiency of Carnot’s engine operating between
reservoirs, maintained at temperatures 27°C and –123°C,
is
(a) 50% (b) 24% (c) 0.75% (d) 0.4%
Q.12The temperature of sink of Carnot engine is 27°C and
Efficiency of engine is 25%. Then temperature of source
is
(a) 227°C (b) 327°C (c) 127°C (d) 27°C
Q.13 In changing the state of thermodynamics from A to B state,
the heat required is Q and the work done by the system is
W. The change in its internal energy is
(a) Q + W (b) Q – W (c) Q (d)
2
QW -
Q.14 The first law of thermodynamics is concerned with the
conservation of
(a) Momentum (b) Energy
(c) Mass (d) Temperature
Q.15A system is given 300 calories of heat and it does 600
joules of work. The internal energy of the system change
in this process is
 (J = 4.18 Joule/cal)
(a) 654 Joule (b) 156.5 Joule
(c) –300 Joule (d) – 528.2 Joule
DPP/ P 25
3
Q.16 110 J of heat is added to a gaseous system, whose internal
energy change is 40 J, then the amount of external work
done is
(a) 150 J (b) 70 J (c) 110 J (d) 40 J
Q.17For free expansion of the gas which of the following is
true
(a) 0 QW == and 
int
0 E D=
(b) 0,0 QW => and 
int
EW D =-
(c) 0,0 WQ => , and 
int
EQ D=
(d) 0,0 WQ >< and 
int
0 E D=
Q.18 In a given process for an ideal gas, 
0 dW =
 and 0 dQ < .
Then for the gas
(a) The temperature will decrease
(b) The volume will increase
(c) The pressure will remain constant
(d) The temperature will increase
Q.19The specific heat of hydrogen gas at constant pressure is
3
3.4 10 cal/kg C =´
o
p
C and at constant volume is
3
2.4 10 cal/kg C =´
o
V
C . If one kilogram hydrogen gas is
heated from 10°C to 20°C at constant pressure, the
external work done on the gas to maintain it at constant
pressure is
(a) 10
5
 cal (b) 10
4
 cal
(c) 10
3
 cal (d) 5 × 10
3
 cal
DIRECTIONS (Q.20-Q.22) : In the following questions,
more than one of the answers  given are correct. Select the
correct answers and mark it according to the following
codes:
Codes : (a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.20Which of the following processes are irreversible?
(1) Transfer of heat by radiation
(2) Electrical heating of a nichrome wire
(3) Transfer of heat by conduction
(4) Isothermal compression
Q.21For a reversible process, unnecessary conditions are
(1) In the whole cycle of the system, the loss of any type
of heat energy should be zero
(2) That the process should be too fast
(3) That the process should be slow so that the working
substance should remain in thermal and mechanical
equilibrium with the surroundings
(4) The loss of energy should be zero and it should be
quasistatic
Q.22 One mole of an ideal gas is taken through the cyclic through
the cyclic process shown in the V-T diagram, where V =
volume and T = absolute temperature of the gas. Which of
the following statements are correct
A B
C
D
V
T
V
0
2V
0
2
0
T T
0
(1) Heat is given out by the gas
(2) Heat is absorbed by the gas
(3) The magnitude of the work done by the gas is R T
0
 (ln 2)
(4) The magnitude of the work done by the gas is V
0
T
0
DIRECTIONS (Q.23-Q.25) : Read the passage given below and
answer the questions that follows :
V-T graph of a process of monoatomic ideal gas is as shown in
figure.
a b
d c
V
T
Q.23 Sum of work done by the gas in process abcd is –
(a) zero (b) positive
(c) negative (d) data is insufficient
Q.24 Heat is supplied to the gas in process(s) –
(a) da, ab and bc (b) da and ab only
(c) da only (d) ab and bc only
Q.25 Change in internal energy of the gas is zero in process(s) –
(a) da, ab and bc (b) da and bc only
(c) da only (d) da and ab only
Page 4


DIRECTIONS (Q.1-Q.19) : There are 19 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 Six moles of an ideal gas performs a cycle shown in figure.
If the temperature 600 , 800 , 2200 = ==
A BC
T KT KT K
and 1200
D
TK = , the work done per cycle is
P
T
A
D
B C
(a) 20 
kJ
(b) 30 
kJ
(c) 40 kJ (d) 60 kJ
Q.2 An ideal gas is taken from point A to the point B , as
shown in the PV - diagram, keeping the temperature
constant. The work done in the process is
P
V
B
A
O
B
P
B
V
A
V
A
P
(a)( )()
A B BA
PP VV -- (b)
1
()()
2
B A BA
PP VV -+
(c)
1
()()
2
BA BA
P P VV -- (d)
1
( )()
2
B A BA
P P VV +-
2
DPP/ P 25
Q.3 In the diagrams (i) to (iv) of variation of volume with
changing pressure is shown. A gas is taken along the path
ABCD. The change in internal energy of the gas will be
(i)
V
P
A
B
C
D
(ii)
V
P
A
B
C D
(iii)
V
P
A
B
C D
(iv)
V
P
A
B
C
D
(a) Positive in all cases (i) to (iv)
(b) Positive in cases (i), (ii) and (iii) but zero in case (iv)
(c) Negative in cases (i), (ii) and (iii) but zero in case (iv)
(d) Zero in all cases
Q.4 A monoatomic ideal gas, initially at temperature T
1
, is
enclosed in a cylinder fitted with a frictionless piston. The
gas is allowed to expand adiabatically to a temperature T
2
by releasing the piston suddenly . If L
1
and L
2
 are the lengths
of the gas column before and after expansion respectively,
then 
12
/ TT is given by
(a)
2/3
1
2
L
L
æö
ç÷
èø
(b)
1
2
L
L
(c)
2
1
L
L
(d)
2/3
2
1
L
L
æö
ç÷
èø
Q.5 A gas mixture consists of 2 moles of oxygen and 4 moles
argon at temperature T. Neglecting all vibrational modes,
the total internal energy of the system is
(a) 4 RT (b) 15 RT (c) 9 RT (d) 11 RT
Q.6 Two Carnot engines A and B are operated in succession.
The first one, A receives heat from a source at 
1
800 TK =
and rejects to sink at 
2
TK . The second engine B receives
heat rejected by the first engine and rejects to another sink
at 
3
300. TK = If the work outputs of two engines are equal,
then the value of T
2
 will be
(a) 100K (b) 300K (c) 550K (d) 700 K
Q.7 A Carnot engine whose low temperature reservoir is at 7°C
has an efficiency of 50%. It is desired to increase the
efficiency to 70%. By how many degrees should the
temperature of the high temperature reservoir be increased
(a) 840K (b) 280 K (c) 560 K (d) 380K
Q.8 An ideal heat engine working between temperature T
1
 and
T
2
 has an efficiency h, the new efficiency of engine if both
the source and sink temperature are doubled, will be
(a)
2
h
(b) h (c)2h (d)3h
Q.9 Efficiency of a Carnot engine is 50% when temperature
of outlet is 500 K. In order to increase efficiency up to
60% keeping temperature of intake the same what will be
temperature of outlet
(a) 200 K (b) 400 K (c) 600 K (d) 800 K
Q.10 A scientist says that the efficiency of his heat engine which
operates at source temperature 120ºC and sink temperature
27ºC is 26%, then
(a) It is impossible
(b) It is possible but less probable
(c) It is quite probable
(d) Data are incomplete
Q.11 The efficiency of Carnot’s engine operating between
reservoirs, maintained at temperatures 27°C and –123°C,
is
(a) 50% (b) 24% (c) 0.75% (d) 0.4%
Q.12The temperature of sink of Carnot engine is 27°C and
Efficiency of engine is 25%. Then temperature of source
is
(a) 227°C (b) 327°C (c) 127°C (d) 27°C
Q.13 In changing the state of thermodynamics from A to B state,
the heat required is Q and the work done by the system is
W. The change in its internal energy is
(a) Q + W (b) Q – W (c) Q (d)
2
QW -
Q.14 The first law of thermodynamics is concerned with the
conservation of
(a) Momentum (b) Energy
(c) Mass (d) Temperature
Q.15A system is given 300 calories of heat and it does 600
joules of work. The internal energy of the system change
in this process is
 (J = 4.18 Joule/cal)
(a) 654 Joule (b) 156.5 Joule
(c) –300 Joule (d) – 528.2 Joule
DPP/ P 25
3
Q.16 110 J of heat is added to a gaseous system, whose internal
energy change is 40 J, then the amount of external work
done is
(a) 150 J (b) 70 J (c) 110 J (d) 40 J
Q.17For free expansion of the gas which of the following is
true
(a) 0 QW == and 
int
0 E D=
(b) 0,0 QW => and 
int
EW D =-
(c) 0,0 WQ => , and 
int
EQ D=
(d) 0,0 WQ >< and 
int
0 E D=
Q.18 In a given process for an ideal gas, 
0 dW =
 and 0 dQ < .
Then for the gas
(a) The temperature will decrease
(b) The volume will increase
(c) The pressure will remain constant
(d) The temperature will increase
Q.19The specific heat of hydrogen gas at constant pressure is
3
3.4 10 cal/kg C =´
o
p
C and at constant volume is
3
2.4 10 cal/kg C =´
o
V
C . If one kilogram hydrogen gas is
heated from 10°C to 20°C at constant pressure, the
external work done on the gas to maintain it at constant
pressure is
(a) 10
5
 cal (b) 10
4
 cal
(c) 10
3
 cal (d) 5 × 10
3
 cal
DIRECTIONS (Q.20-Q.22) : In the following questions,
more than one of the answers  given are correct. Select the
correct answers and mark it according to the following
codes:
Codes : (a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.20Which of the following processes are irreversible?
(1) Transfer of heat by radiation
(2) Electrical heating of a nichrome wire
(3) Transfer of heat by conduction
(4) Isothermal compression
Q.21For a reversible process, unnecessary conditions are
(1) In the whole cycle of the system, the loss of any type
of heat energy should be zero
(2) That the process should be too fast
(3) That the process should be slow so that the working
substance should remain in thermal and mechanical
equilibrium with the surroundings
(4) The loss of energy should be zero and it should be
quasistatic
Q.22 One mole of an ideal gas is taken through the cyclic through
the cyclic process shown in the V-T diagram, where V =
volume and T = absolute temperature of the gas. Which of
the following statements are correct
A B
C
D
V
T
V
0
2V
0
2
0
T T
0
(1) Heat is given out by the gas
(2) Heat is absorbed by the gas
(3) The magnitude of the work done by the gas is R T
0
 (ln 2)
(4) The magnitude of the work done by the gas is V
0
T
0
DIRECTIONS (Q.23-Q.25) : Read the passage given below and
answer the questions that follows :
V-T graph of a process of monoatomic ideal gas is as shown in
figure.
a b
d c
V
T
Q.23 Sum of work done by the gas in process abcd is –
(a) zero (b) positive
(c) negative (d) data is insufficient
Q.24 Heat is supplied to the gas in process(s) –
(a) da, ab and bc (b) da and ab only
(c) da only (d) ab and bc only
Q.25 Change in internal energy of the gas is zero in process(s) –
(a) da, ab and bc (b) da and bc only
(c) da only (d) da and ab only
4
DPP/ P 25
DIRECTIONS (Q.26-Q.28) : Each of these questions contains two
sta tements: S tatem ent-1 (Ass ertio n) an d S tatement-2 (Reaso n). E ach
of these questions has four alternative choices, only one of which is
the correct answer . Y ou have to select the correct choice.
(a) Statement-1 is True, Statement-2 is True; Statement-2 is a
correct explanation for  Statement-1.
(b) Statement-1 is True, Statement-2 is True; Statement-2 is
NOT a correct explanation for Statement-1.
(c) Statement -1 is False, Statement-2 is True.
(d) Statement -1 is True, Statement-2 is False.
Q.26 Statement-1 : It is not possible for a system, unaided by an
external agency to transfer heat from a body at lower
temperature to another body at higher temperature.
Statement-2 : According to Clausius statement, “No
process is possible whose sole result is the transfer of
heat from a cooled object to a hotter object.
Q.27 Statement-1 : A room can be warmed by opening the door
of a refrigerator in a closed room.
Statement-2 : Head flows from lower temperature
(refrigerator) to higher temperature (room).
Q.28 Statement-1 : In isothermal process whole of the heat
energy supplied to the body is converted into internal
energy.
Statement-2 : According to the first law of themodynamics
Q U PV D =D +D