Thermodynamics- 1 Practice Questions - DPP for NEET

 Page 1


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 For an isothermal expansion of a perfect gas, the value of
P
P
D
 is
(a)
1/2
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g
(d)
2
V
V
D
-g
Q.2 When an ideal gas in a cylinder was compressed
isothermally by a piston, the work done on the gas was
found to be 1.5 × 10
4
 Joule. During this process about
(a) 3.6 × 10
3
 cal of heat flowed out from the gas
(b) 3.6 × 10
3
 cal of heat flowed into the gas
(c) 1.5 × 10
4
 cal of heat flowed into the gas
(d) 1.5 × 10
4
 cal of heat flowed out from the gas
Q.3 The latent heat of vaporisation of water is 2240 J/gm. If
the work done in the process of expansion of 1 g of water
is 168 J, then increase in internal energy is
(a) 2408 J (b) 2240 J
(c) 2072 J (d) 1904 J
Q.4 One mole of an ideal gas expands at a constant temperature
of 300 K from an initial volume of 10 litres to a final
volume of 20 litres. The work done in expanding the gas is
( 8.31 J/mole K) R=-
(a) 750 Joules (b) 1728 Joules
(c) 1500 Joules (d) 3456 Joules
Page 2


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 For an isothermal expansion of a perfect gas, the value of
P
P
D
 is
(a)
1/2
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g
(d)
2
V
V
D
-g
Q.2 When an ideal gas in a cylinder was compressed
isothermally by a piston, the work done on the gas was
found to be 1.5 × 10
4
 Joule. During this process about
(a) 3.6 × 10
3
 cal of heat flowed out from the gas
(b) 3.6 × 10
3
 cal of heat flowed into the gas
(c) 1.5 × 10
4
 cal of heat flowed into the gas
(d) 1.5 × 10
4
 cal of heat flowed out from the gas
Q.3 The latent heat of vaporisation of water is 2240 J/gm. If
the work done in the process of expansion of 1 g of water
is 168 J, then increase in internal energy is
(a) 2408 J (b) 2240 J
(c) 2072 J (d) 1904 J
Q.4 One mole of an ideal gas expands at a constant temperature
of 300 K from an initial volume of 10 litres to a final
volume of 20 litres. The work done in expanding the gas is
( 8.31 J/mole K) R=-
(a) 750 Joules (b) 1728 Joules
(c) 1500 Joules (d) 3456 Joules
2
DPP/ P 24
Q.5 The pressure in the tyre of a car is four times the
atmospheric pressure at 300 K. If this tyre suddenly bursts,
its new tempera ture will be ( 1.4) g=
(a)
1.4/0.4
300(4) (b)
0.4/1.4
1
300
4
-
æö
ç÷
èø
(c)
0.4/1.4
300(2)
-
(d)
0.4/1.4
300(4)
-
Q.6 A monoatomic gas ( 5/ 3) g= is suddenly compressed to
1
8
 of its original volume adiabatically, then the pressure
of the gas will change to
(a)
24
5
(b)8
(c)
40
3
(d) 32 times its initial pre ssure
Q.7 An ideal gas at 27°C is compressed adiabatically to 
8
27
of
its original volume. If 
5
3
g= , then the rise in temperature
is
(a) 450 K     (b) 375 k (c) 225 K (d) 405 K
Q.8 A given system undergoes a change in which the work done
by the system equals the decrease in its internal energy.
The system must have undergone an
(a) Isothermal change (b) Adiabatic change
(c) Isobaric change (d) Isochoric change
Q.9 Helium at 27° has a volume of 8 litres. It is suddenly
compressed to a volume of 1 litre.  The temperature of the
gas will be [ 5 / 3] g=
(a) 108°C (b) 9327°C (c) 1200°C (d) 927°C
Q.10 One mole of an ideal gas at an initial temperature of TK
does 6 R joules of work adiabatically. If the ratio of
specific heats of this gas at constant pressure and at
constant volume is 5/3, the final temperature of gas will
be
(a) ( 2.4) TK + (b) ( 2.4) TK -
(c) ( 4) TK + (d) ( 4) TK -
Q.11 For an adiabatic expansion of a perfect gas, the value of
P
P
D
is equal to
(a)
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g (d)
2
V
V
D
-g
Q.12If 300 ml of gas at 27°C is cooled to 7°C  at constant
pressure, then its final volume will be
(a) 540 ml (b) 350 ml
(c) 280 ml (d) 135 ml
Q.13 A sample of gas expands from volume 
1
V to 
2
V . The amount
of work done by the gas is greatest when the expansion is
(a) isothermal (b) isobaric
(c) adiabatic (d) equal in all cases
Q.14 How much work to be done in decreasing the volume of
and ideal gas by an amount of 
43
2.4 10 m
-
´ at normal
temperature and constant normal pressure of 
52
1 10 /m N ´
(a) 28 Joule (b) 27 Joule
(c) 25 Joule (d) 24 Joule
Q.15 One mole of a perfect gas in a cylinder fitted with a piston has
a pressure P , volume V and temperature T . If the temperature
is increased by 1 K keeping pressure constant, the increase in
volume is
(a)
2
273
V
(b)
91
V
(c)
273
V
(d)V
Q.16Work done by 0.1 mole of a gas at 27C
o
 to double its
volume at constant pressure is 
11
( 2calmol K) R
--
=
o
(a) 54 cal (b) 600 cal (c) 60 cal (d) 546 cal
Q.17 When an ideal diatomic gas is heated at constant pressure,
the fraction of the heat energy supplied which increases
the internal energy of the gas, is
(a)
2
5
(b)
3
5
(c)
3
7
(d)
5
7
Page 3


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 For an isothermal expansion of a perfect gas, the value of
P
P
D
 is
(a)
1/2
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g
(d)
2
V
V
D
-g
Q.2 When an ideal gas in a cylinder was compressed
isothermally by a piston, the work done on the gas was
found to be 1.5 × 10
4
 Joule. During this process about
(a) 3.6 × 10
3
 cal of heat flowed out from the gas
(b) 3.6 × 10
3
 cal of heat flowed into the gas
(c) 1.5 × 10
4
 cal of heat flowed into the gas
(d) 1.5 × 10
4
 cal of heat flowed out from the gas
Q.3 The latent heat of vaporisation of water is 2240 J/gm. If
the work done in the process of expansion of 1 g of water
is 168 J, then increase in internal energy is
(a) 2408 J (b) 2240 J
(c) 2072 J (d) 1904 J
Q.4 One mole of an ideal gas expands at a constant temperature
of 300 K from an initial volume of 10 litres to a final
volume of 20 litres. The work done in expanding the gas is
( 8.31 J/mole K) R=-
(a) 750 Joules (b) 1728 Joules
(c) 1500 Joules (d) 3456 Joules
2
DPP/ P 24
Q.5 The pressure in the tyre of a car is four times the
atmospheric pressure at 300 K. If this tyre suddenly bursts,
its new tempera ture will be ( 1.4) g=
(a)
1.4/0.4
300(4) (b)
0.4/1.4
1
300
4
-
æö
ç÷
èø
(c)
0.4/1.4
300(2)
-
(d)
0.4/1.4
300(4)
-
Q.6 A monoatomic gas ( 5/ 3) g= is suddenly compressed to
1
8
 of its original volume adiabatically, then the pressure
of the gas will change to
(a)
24
5
(b)8
(c)
40
3
(d) 32 times its initial pre ssure
Q.7 An ideal gas at 27°C is compressed adiabatically to 
8
27
of
its original volume. If 
5
3
g= , then the rise in temperature
is
(a) 450 K     (b) 375 k (c) 225 K (d) 405 K
Q.8 A given system undergoes a change in which the work done
by the system equals the decrease in its internal energy.
The system must have undergone an
(a) Isothermal change (b) Adiabatic change
(c) Isobaric change (d) Isochoric change
Q.9 Helium at 27° has a volume of 8 litres. It is suddenly
compressed to a volume of 1 litre.  The temperature of the
gas will be [ 5 / 3] g=
(a) 108°C (b) 9327°C (c) 1200°C (d) 927°C
Q.10 One mole of an ideal gas at an initial temperature of TK
does 6 R joules of work adiabatically. If the ratio of
specific heats of this gas at constant pressure and at
constant volume is 5/3, the final temperature of gas will
be
(a) ( 2.4) TK + (b) ( 2.4) TK -
(c) ( 4) TK + (d) ( 4) TK -
Q.11 For an adiabatic expansion of a perfect gas, the value of
P
P
D
is equal to
(a)
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g (d)
2
V
V
D
-g
Q.12If 300 ml of gas at 27°C is cooled to 7°C  at constant
pressure, then its final volume will be
(a) 540 ml (b) 350 ml
(c) 280 ml (d) 135 ml
Q.13 A sample of gas expands from volume 
1
V to 
2
V . The amount
of work done by the gas is greatest when the expansion is
(a) isothermal (b) isobaric
(c) adiabatic (d) equal in all cases
Q.14 How much work to be done in decreasing the volume of
and ideal gas by an amount of 
43
2.4 10 m
-
´ at normal
temperature and constant normal pressure of 
52
1 10 /m N ´
(a) 28 Joule (b) 27 Joule
(c) 25 Joule (d) 24 Joule
Q.15 One mole of a perfect gas in a cylinder fitted with a piston has
a pressure P , volume V and temperature T . If the temperature
is increased by 1 K keeping pressure constant, the increase in
volume is
(a)
2
273
V
(b)
91
V
(c)
273
V
(d)V
Q.16Work done by 0.1 mole of a gas at 27C
o
 to double its
volume at constant pressure is 
11
( 2calmol K) R
--
=
o
(a) 54 cal (b) 600 cal (c) 60 cal (d) 546 cal
Q.17 When an ideal diatomic gas is heated at constant pressure,
the fraction of the heat energy supplied which increases
the internal energy of the gas, is
(a)
2
5
(b)
3
5
(c)
3
7
(d)
5
7
DPP/ P 24
3
Q.18When heat is given to a gas in an isothermal change, the
result will be
(a) external work done
(b) rise in temperature
(c) increase in internal energy
(d) external work done and also rise in temp.
Q.19An ideal gas expands isothermally from a volume 
1
V to
2
V and then compressed to original volume 
1
V
adiabatically. Initial pressure is 
1
P and final pressure is
3
P . The total work done is 
W
. Then
(a)
31
,0 P PW >> (b)
31
,0 P PW <<
(c)
31
,0 P PW >< (d)
31
,0 P PW ==
Q.20 An ideal gas expands in such a manner that its pressure and
volume can be related by equation 
2
PV = constant. During
this process, the gas is
(a) heated
(b) cooled
(c) neither heated nor cooled
(d) first heated and then cooled
Q.21In the following 
PV -
diagram two adiabatics cut two
isothermals at temperatures 
1
T and 
2
T (fig.). The value of
a
d
V
V
 will be
P
V
a
b
d
2
T
1
T
a
V
b
V
d
V
c
V
(a)
b
c
V
V
(b)
c
b
V
V
(c)
d
a
V
V
(d)
bc
VV
DIRECTIONS (Q.22 - Q.23) : 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.22During the melting of a slab of ice at 273 K and one
atmospheric pressure
(1) Positive work is done on the ice-water system by the
atmosphere
(2) Positive work is done by ice-water system on the
atmosphere
(3) The internal energy of the ice-water system increases
(4) The internal energy of the ice-water system decreases
Q.23 One mole of an ideal monatomic gas is taken from A to C
along the path ABC. The temperature of the gas at A is T
0
.
For the process ABC –
P
C
V
0
2V
0
2P
0
P
0 B
A
T
0
(1) Work done by the gas is RT
0
(2) Change in internal energy of the gas is 
0
11
RT
2
(3) Heat absorbed by the gas is 
0
11
RT
2
(4) Heat absorbed by the gas is 
0
13
RT
2
DIRECTIONS (Q.24-Q.26) : Read the passage given below
and answer the questions that follows :
In the figure n mole of a monoatomic ideal gas undergo the
process ABC as shown in the P-V diagram. The process AB is
isothermal and BC is isochoric. The temperature of the gas at A
is T
0
. Total heat given to the gas during the process ABC is
measured to be Q.
Page 4


DIRECTIONS (Q.1-Q.21) : There are 21 multiple choice questions.
Each question has 4 choices (a), (b), (c) and (d), out of which ONLY
ONE choice is correct.
Q.1 For an isothermal expansion of a perfect gas, the value of
P
P
D
 is
(a)
1/2
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g
(d)
2
V
V
D
-g
Q.2 When an ideal gas in a cylinder was compressed
isothermally by a piston, the work done on the gas was
found to be 1.5 × 10
4
 Joule. During this process about
(a) 3.6 × 10
3
 cal of heat flowed out from the gas
(b) 3.6 × 10
3
 cal of heat flowed into the gas
(c) 1.5 × 10
4
 cal of heat flowed into the gas
(d) 1.5 × 10
4
 cal of heat flowed out from the gas
Q.3 The latent heat of vaporisation of water is 2240 J/gm. If
the work done in the process of expansion of 1 g of water
is 168 J, then increase in internal energy is
(a) 2408 J (b) 2240 J
(c) 2072 J (d) 1904 J
Q.4 One mole of an ideal gas expands at a constant temperature
of 300 K from an initial volume of 10 litres to a final
volume of 20 litres. The work done in expanding the gas is
( 8.31 J/mole K) R=-
(a) 750 Joules (b) 1728 Joules
(c) 1500 Joules (d) 3456 Joules
2
DPP/ P 24
Q.5 The pressure in the tyre of a car is four times the
atmospheric pressure at 300 K. If this tyre suddenly bursts,
its new tempera ture will be ( 1.4) g=
(a)
1.4/0.4
300(4) (b)
0.4/1.4
1
300
4
-
æö
ç÷
èø
(c)
0.4/1.4
300(2)
-
(d)
0.4/1.4
300(4)
-
Q.6 A monoatomic gas ( 5/ 3) g= is suddenly compressed to
1
8
 of its original volume adiabatically, then the pressure
of the gas will change to
(a)
24
5
(b)8
(c)
40
3
(d) 32 times its initial pre ssure
Q.7 An ideal gas at 27°C is compressed adiabatically to 
8
27
of
its original volume. If 
5
3
g= , then the rise in temperature
is
(a) 450 K     (b) 375 k (c) 225 K (d) 405 K
Q.8 A given system undergoes a change in which the work done
by the system equals the decrease in its internal energy.
The system must have undergone an
(a) Isothermal change (b) Adiabatic change
(c) Isobaric change (d) Isochoric change
Q.9 Helium at 27° has a volume of 8 litres. It is suddenly
compressed to a volume of 1 litre.  The temperature of the
gas will be [ 5 / 3] g=
(a) 108°C (b) 9327°C (c) 1200°C (d) 927°C
Q.10 One mole of an ideal gas at an initial temperature of TK
does 6 R joules of work adiabatically. If the ratio of
specific heats of this gas at constant pressure and at
constant volume is 5/3, the final temperature of gas will
be
(a) ( 2.4) TK + (b) ( 2.4) TK -
(c) ( 4) TK + (d) ( 4) TK -
Q.11 For an adiabatic expansion of a perfect gas, the value of
P
P
D
is equal to
(a)
V
V
D
-g
(b)
V
V
D
-
(c)
V
V
D
-g (d)
2
V
V
D
-g
Q.12If 300 ml of gas at 27°C is cooled to 7°C  at constant
pressure, then its final volume will be
(a) 540 ml (b) 350 ml
(c) 280 ml (d) 135 ml
Q.13 A sample of gas expands from volume 
1
V to 
2
V . The amount
of work done by the gas is greatest when the expansion is
(a) isothermal (b) isobaric
(c) adiabatic (d) equal in all cases
Q.14 How much work to be done in decreasing the volume of
and ideal gas by an amount of 
43
2.4 10 m
-
´ at normal
temperature and constant normal pressure of 
52
1 10 /m N ´
(a) 28 Joule (b) 27 Joule
(c) 25 Joule (d) 24 Joule
Q.15 One mole of a perfect gas in a cylinder fitted with a piston has
a pressure P , volume V and temperature T . If the temperature
is increased by 1 K keeping pressure constant, the increase in
volume is
(a)
2
273
V
(b)
91
V
(c)
273
V
(d)V
Q.16Work done by 0.1 mole of a gas at 27C
o
 to double its
volume at constant pressure is 
11
( 2calmol K) R
--
=
o
(a) 54 cal (b) 600 cal (c) 60 cal (d) 546 cal
Q.17 When an ideal diatomic gas is heated at constant pressure,
the fraction of the heat energy supplied which increases
the internal energy of the gas, is
(a)
2
5
(b)
3
5
(c)
3
7
(d)
5
7
DPP/ P 24
3
Q.18When heat is given to a gas in an isothermal change, the
result will be
(a) external work done
(b) rise in temperature
(c) increase in internal energy
(d) external work done and also rise in temp.
Q.19An ideal gas expands isothermally from a volume 
1
V to
2
V and then compressed to original volume 
1
V
adiabatically. Initial pressure is 
1
P and final pressure is
3
P . The total work done is 
W
. Then
(a)
31
,0 P PW >> (b)
31
,0 P PW <<
(c)
31
,0 P PW >< (d)
31
,0 P PW ==
Q.20 An ideal gas expands in such a manner that its pressure and
volume can be related by equation 
2
PV = constant. During
this process, the gas is
(a) heated
(b) cooled
(c) neither heated nor cooled
(d) first heated and then cooled
Q.21In the following 
PV -
diagram two adiabatics cut two
isothermals at temperatures 
1
T and 
2
T (fig.). The value of
a
d
V
V
 will be
P
V
a
b
d
2
T
1
T
a
V
b
V
d
V
c
V
(a)
b
c
V
V
(b)
c
b
V
V
(c)
d
a
V
V
(d)
bc
VV
DIRECTIONS (Q.22 - Q.23) : 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.22During the melting of a slab of ice at 273 K and one
atmospheric pressure
(1) Positive work is done on the ice-water system by the
atmosphere
(2) Positive work is done by ice-water system on the
atmosphere
(3) The internal energy of the ice-water system increases
(4) The internal energy of the ice-water system decreases
Q.23 One mole of an ideal monatomic gas is taken from A to C
along the path ABC. The temperature of the gas at A is T
0
.
For the process ABC –
P
C
V
0
2V
0
2P
0
P
0 B
A
T
0
(1) Work done by the gas is RT
0
(2) Change in internal energy of the gas is 
0
11
RT
2
(3) Heat absorbed by the gas is 
0
11
RT
2
(4) Heat absorbed by the gas is 
0
13
RT
2
DIRECTIONS (Q.24-Q.26) : Read the passage given below
and answer the questions that follows :
In the figure n mole of a monoatomic ideal gas undergo the
process ABC as shown in the P-V diagram. The process AB is
isothermal and BC is isochoric. The temperature of the gas at A
is T
0
. Total heat given to the gas during the process ABC is
measured to be Q.
4
DPP/ P 24
P
A C
B
2V 6V
Q.24 Temperature of the gas at C is equal to
(a) T
0
(b) 3 T
0
(c)6 T
0
(d) 2 T
0
Q.25 Heat absorbed by the gas in the process BC
(a)3nRT
0
(b) nRT
0
(c)2nRT
0
(d)6nRT
0
Q.26 The average molar heat capacity of the gas in process ABC
is
(a)
0
Q
nT
(b) 
0
2
Q
nT
(c)
0
3
Q
nT
(d)
0
2Q
nT
DIRECTIONS (Q. 27-Q.29) : Each of these questions contains
two statements: Statement-1 (Assertion) and Statement-2
(Reason). Each of these questions has four alternative choices,
only one of which is the correct answer. You 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.27 Statement-1 : The isothermal curves intersect each other
at a certain point.
Statement-2 : The isothermal change takes place slowly,
so the isothermal curves have very little slope.
Q.28 Statement-1 : In adiabatic compression, the internal
energy and temperature of the system get increased.
Statement-2 : The adiabatic compression is a slow process.
Q.29 Statement-1 : The specific heat of a gas in an adiabatic
process is zero and in an isothermal process is infinite.
Statement-2 : Specific heat of a gas is directly proportional
to change of heat in system and inversely proportional to
change in temperature.