DC Pandey Solutions (JEE Advance): First Law of Thermodynamics | DC Pandey Solutions for JEE Physics PDF Download

 Page 1


For JEE Advanced 
Objective Questions 
  Single Correct Option 
Q 1.  1 mole of an ideal gas is taken through a cyclic process. The minimum temperature during the 
cycle is 300 K. Then net exchange of heat for complete cycle is 
 
  (a) 600 R In 2   (b) 300 R In 2   (c)-300 R ln 2   (d) 900 R In 2 
Q 2.  Two moles of an ideal gas are undergone a cyclic process 1-2-3-1. If net heat exchange in the 
process is 300 J, the work done by the gas in the process 2-3 is 
 
  (a) -500 J   (b) – 5000 J   (c) – 3000 J   (d) None of these 
Q 3.  Two cylinders fitted with pistons contain equal amount of an ideal diatomic gas at 300 K. The 
piston of A is free to move, while that of B is held fixed. The same amount of heat is given to the 
gas in each cylinder. If the rise in temperature of the gas in A is 30 K, then the rise in temperature 
of gas in B is 
  (a) 30 K   (b) 18 K   (c) 50 K   (d) 42 K 
Q 4.  A gas follows a process TV
n-1
 = constant, where T = absolute temperature of the gas and V = 
volume of the gas. The bulk modulus of the gas in the process is given by 
  (a) (n - 1)P   (b) P/(n-1)   (c) nP    (d) P/n 
Q 5.  A cyclic process 1-2-3-4-1 is depicted on V-T diagram. The P-T and P-V diagrams for this cyclic 
process are given below. Select the correct choices (more than one options is/are correct) 
 
  (a)  (b) (c)  (d) None of these 
Page 2


For JEE Advanced 
Objective Questions 
  Single Correct Option 
Q 1.  1 mole of an ideal gas is taken through a cyclic process. The minimum temperature during the 
cycle is 300 K. Then net exchange of heat for complete cycle is 
 
  (a) 600 R In 2   (b) 300 R In 2   (c)-300 R ln 2   (d) 900 R In 2 
Q 2.  Two moles of an ideal gas are undergone a cyclic process 1-2-3-1. If net heat exchange in the 
process is 300 J, the work done by the gas in the process 2-3 is 
 
  (a) -500 J   (b) – 5000 J   (c) – 3000 J   (d) None of these 
Q 3.  Two cylinders fitted with pistons contain equal amount of an ideal diatomic gas at 300 K. The 
piston of A is free to move, while that of B is held fixed. The same amount of heat is given to the 
gas in each cylinder. If the rise in temperature of the gas in A is 30 K, then the rise in temperature 
of gas in B is 
  (a) 30 K   (b) 18 K   (c) 50 K   (d) 42 K 
Q 4.  A gas follows a process TV
n-1
 = constant, where T = absolute temperature of the gas and V = 
volume of the gas. The bulk modulus of the gas in the process is given by 
  (a) (n - 1)P   (b) P/(n-1)   (c) nP    (d) P/n 
Q 5.  A cyclic process 1-2-3-4-1 is depicted on V-T diagram. The P-T and P-V diagrams for this cyclic 
process are given below. Select the correct choices (more than one options is/are correct) 
 
  (a)  (b) (c)  (d) None of these 
Q 6.  One mole of an ideal gas at temperature T1 expands slowly according to the law P/V - constant. Its 
final temperature is T2. The work done by the gas is 
  (a) R(T2 - T1)   (b) 2R(T2 - T1)  (c) 
21
R
(T T )
2
? (d) 
21
2R
(T T )
3
? 
Q 7.  In a process the pressure of an ideal gas is proportional to square of the volume of the gas. If the 
temperature of the gas increases in this process, then work done by this gas 
  (a) is positive   (b) is negative  (c) is zero   (d) may be positive or negative 
Q 8.  n moles of a gas are filled in a container at temperature T. If the gas is slowly and isothermally 
compressed to half its initial volume, the work done
 
by the atmosphere on the gas is 
 
 (a) 
nRT
2
   (b) 
nRT
2
?
  
(c) nRT ln 2   (d) - nRT ln 2 
Q 9.  600 J of heat is added to a monoatomic gas in a process in which the gas performs a work of 150 J. 
The molar heat capacity for the process is 
  (a) 3R    (b) 4R   (c) 2R    (d) 6R 
Q 10.  A gas undergoes A to B through three different processes 1, 2 and 3 as shown in the figure. The 
heat supplied to the gas is Q1, Q2 and Q3 respectively, then 
 
  (a) Q1 = Q2 = Q 3  (b) Q1 < Q2 < Q3 (c) Q1 > Q2 > Q 3  (d) Q1 = Q3 > Q2  
Q 11.  The internal energy of a gas is given by U = 2PV. It expands from V0 to 2V0 against a constant 
pressure P0. The heat absorbed by the gas in the process is 
  (a) 2P0V0   (b) 4P0V0   (c) 3P0V0   (d) P0V0 
Q 12.  For an adiabatic compression the quantity PV 
  (a) increases   (b) decreases   (c) remains constant  (d) depends on 
Q 13.  The figure shows two paths for the change of state of a gas from A to B. The ratio of molar heat 
capacities in path 1 and path 2 is 
 
  (a) < 1    (b) > 1   (c) 1    (d) Data insufficient 
Q 14.  P-T diagram of one mole of an ideal monoatomic gas is shown. Processes AB and CD are 
adiabatic. Work done in the complete cycle is 
Page 3


For JEE Advanced 
Objective Questions 
  Single Correct Option 
Q 1.  1 mole of an ideal gas is taken through a cyclic process. The minimum temperature during the 
cycle is 300 K. Then net exchange of heat for complete cycle is 
 
  (a) 600 R In 2   (b) 300 R In 2   (c)-300 R ln 2   (d) 900 R In 2 
Q 2.  Two moles of an ideal gas are undergone a cyclic process 1-2-3-1. If net heat exchange in the 
process is 300 J, the work done by the gas in the process 2-3 is 
 
  (a) -500 J   (b) – 5000 J   (c) – 3000 J   (d) None of these 
Q 3.  Two cylinders fitted with pistons contain equal amount of an ideal diatomic gas at 300 K. The 
piston of A is free to move, while that of B is held fixed. The same amount of heat is given to the 
gas in each cylinder. If the rise in temperature of the gas in A is 30 K, then the rise in temperature 
of gas in B is 
  (a) 30 K   (b) 18 K   (c) 50 K   (d) 42 K 
Q 4.  A gas follows a process TV
n-1
 = constant, where T = absolute temperature of the gas and V = 
volume of the gas. The bulk modulus of the gas in the process is given by 
  (a) (n - 1)P   (b) P/(n-1)   (c) nP    (d) P/n 
Q 5.  A cyclic process 1-2-3-4-1 is depicted on V-T diagram. The P-T and P-V diagrams for this cyclic 
process are given below. Select the correct choices (more than one options is/are correct) 
 
  (a)  (b) (c)  (d) None of these 
Q 6.  One mole of an ideal gas at temperature T1 expands slowly according to the law P/V - constant. Its 
final temperature is T2. The work done by the gas is 
  (a) R(T2 - T1)   (b) 2R(T2 - T1)  (c) 
21
R
(T T )
2
? (d) 
21
2R
(T T )
3
? 
Q 7.  In a process the pressure of an ideal gas is proportional to square of the volume of the gas. If the 
temperature of the gas increases in this process, then work done by this gas 
  (a) is positive   (b) is negative  (c) is zero   (d) may be positive or negative 
Q 8.  n moles of a gas are filled in a container at temperature T. If the gas is slowly and isothermally 
compressed to half its initial volume, the work done
 
by the atmosphere on the gas is 
 
 (a) 
nRT
2
   (b) 
nRT
2
?
  
(c) nRT ln 2   (d) - nRT ln 2 
Q 9.  600 J of heat is added to a monoatomic gas in a process in which the gas performs a work of 150 J. 
The molar heat capacity for the process is 
  (a) 3R    (b) 4R   (c) 2R    (d) 6R 
Q 10.  A gas undergoes A to B through three different processes 1, 2 and 3 as shown in the figure. The 
heat supplied to the gas is Q1, Q2 and Q3 respectively, then 
 
  (a) Q1 = Q2 = Q 3  (b) Q1 < Q2 < Q3 (c) Q1 > Q2 > Q 3  (d) Q1 = Q3 > Q2  
Q 11.  The internal energy of a gas is given by U = 2PV. It expands from V0 to 2V0 against a constant 
pressure P0. The heat absorbed by the gas in the process is 
  (a) 2P0V0   (b) 4P0V0   (c) 3P0V0   (d) P0V0 
Q 12.  For an adiabatic compression the quantity PV 
  (a) increases   (b) decreases   (c) remains constant  (d) depends on 
Q 13.  The figure shows two paths for the change of state of a gas from A to B. The ratio of molar heat 
capacities in path 1 and path 2 is 
 
  (a) < 1    (b) > 1   (c) 1    (d) Data insufficient 
Q 14.  P-T diagram of one mole of an ideal monoatomic gas is shown. Processes AB and CD are 
adiabatic. Work done in the complete cycle is 
/ 
  (a) 2.5 RT   (b) -2RT   (c) 1.5 RT   (d) -3.5 RT 
Q 15.  An ideal monoatomic gas undergoes a process in which its internal energy U and density ?
 
vary as
 
U ? 
= constant. The ratio of change in internal energy and the work done by the gas is 
 (a) 
3
2
    (b) 
2
3
    (c) 
1
3
    (d) 
3
5
  
Q 16.  The given figure shows the variation of force applied by ideal gas on a piston which undergoes a 
process during which piston position changes from 0.1 to 0.4 m. If the internal energy of the 
system at the end of the process is 2.5 J higher, then the heat absorbed during the process is 
 
  (a) 15 J   (b) 17.5 J  (c) 20 J   (d) 22.5 J 
Q 17.  A gas can expand through two processes : (i) isobaric, (ii) P/V = constant. Assuming that the 
initial volume is same in both processes and the final volume which is two times the initial volume 
is also same in both processes, which of the following is true? 
  (a) Work done by gas in process (i) is greater than the work done by the gas in process (ii) 
  (b) Work done by gas in process (i) is smaller than the work done by the gas in process (ii) 
  (c) Final pressure is greater in process (i) 
  (d) Final temperature is greater in process (i) 
Q 18.  The cyclic process form a circle on a PV diagram as shown in figure. The work done by the gas is 
 
 (a) 
2
21
(P P )
4
?
?  (b) 
2
21
(V V )
4
?
? (c) 
2 1 2 1
(P P )(V V )
2
?
??  (d) 
2 1 2 1
(P P )(V V )
4
?
?? 
Q 19.  The equation of a state of a gas is given by P(V - b) = nRT. If 1 mole of a gas is isothermally 
expanded from volume V and 2 V, the work done during the process is 
 (a) 
2V b
RTln
Vb
?
?
 (b) 
Vb
RT ln
V
?
 (c) 
Vb
RTln
2V b
?
?
 (d) 
V
RT ln
Vb ?
 
Page 4


For JEE Advanced 
Objective Questions 
  Single Correct Option 
Q 1.  1 mole of an ideal gas is taken through a cyclic process. The minimum temperature during the 
cycle is 300 K. Then net exchange of heat for complete cycle is 
 
  (a) 600 R In 2   (b) 300 R In 2   (c)-300 R ln 2   (d) 900 R In 2 
Q 2.  Two moles of an ideal gas are undergone a cyclic process 1-2-3-1. If net heat exchange in the 
process is 300 J, the work done by the gas in the process 2-3 is 
 
  (a) -500 J   (b) – 5000 J   (c) – 3000 J   (d) None of these 
Q 3.  Two cylinders fitted with pistons contain equal amount of an ideal diatomic gas at 300 K. The 
piston of A is free to move, while that of B is held fixed. The same amount of heat is given to the 
gas in each cylinder. If the rise in temperature of the gas in A is 30 K, then the rise in temperature 
of gas in B is 
  (a) 30 K   (b) 18 K   (c) 50 K   (d) 42 K 
Q 4.  A gas follows a process TV
n-1
 = constant, where T = absolute temperature of the gas and V = 
volume of the gas. The bulk modulus of the gas in the process is given by 
  (a) (n - 1)P   (b) P/(n-1)   (c) nP    (d) P/n 
Q 5.  A cyclic process 1-2-3-4-1 is depicted on V-T diagram. The P-T and P-V diagrams for this cyclic 
process are given below. Select the correct choices (more than one options is/are correct) 
 
  (a)  (b) (c)  (d) None of these 
Q 6.  One mole of an ideal gas at temperature T1 expands slowly according to the law P/V - constant. Its 
final temperature is T2. The work done by the gas is 
  (a) R(T2 - T1)   (b) 2R(T2 - T1)  (c) 
21
R
(T T )
2
? (d) 
21
2R
(T T )
3
? 
Q 7.  In a process the pressure of an ideal gas is proportional to square of the volume of the gas. If the 
temperature of the gas increases in this process, then work done by this gas 
  (a) is positive   (b) is negative  (c) is zero   (d) may be positive or negative 
Q 8.  n moles of a gas are filled in a container at temperature T. If the gas is slowly and isothermally 
compressed to half its initial volume, the work done
 
by the atmosphere on the gas is 
 
 (a) 
nRT
2
   (b) 
nRT
2
?
  
(c) nRT ln 2   (d) - nRT ln 2 
Q 9.  600 J of heat is added to a monoatomic gas in a process in which the gas performs a work of 150 J. 
The molar heat capacity for the process is 
  (a) 3R    (b) 4R   (c) 2R    (d) 6R 
Q 10.  A gas undergoes A to B through three different processes 1, 2 and 3 as shown in the figure. The 
heat supplied to the gas is Q1, Q2 and Q3 respectively, then 
 
  (a) Q1 = Q2 = Q 3  (b) Q1 < Q2 < Q3 (c) Q1 > Q2 > Q 3  (d) Q1 = Q3 > Q2  
Q 11.  The internal energy of a gas is given by U = 2PV. It expands from V0 to 2V0 against a constant 
pressure P0. The heat absorbed by the gas in the process is 
  (a) 2P0V0   (b) 4P0V0   (c) 3P0V0   (d) P0V0 
Q 12.  For an adiabatic compression the quantity PV 
  (a) increases   (b) decreases   (c) remains constant  (d) depends on 
Q 13.  The figure shows two paths for the change of state of a gas from A to B. The ratio of molar heat 
capacities in path 1 and path 2 is 
 
  (a) < 1    (b) > 1   (c) 1    (d) Data insufficient 
Q 14.  P-T diagram of one mole of an ideal monoatomic gas is shown. Processes AB and CD are 
adiabatic. Work done in the complete cycle is 
/ 
  (a) 2.5 RT   (b) -2RT   (c) 1.5 RT   (d) -3.5 RT 
Q 15.  An ideal monoatomic gas undergoes a process in which its internal energy U and density ?
 
vary as
 
U ? 
= constant. The ratio of change in internal energy and the work done by the gas is 
 (a) 
3
2
    (b) 
2
3
    (c) 
1
3
    (d) 
3
5
  
Q 16.  The given figure shows the variation of force applied by ideal gas on a piston which undergoes a 
process during which piston position changes from 0.1 to 0.4 m. If the internal energy of the 
system at the end of the process is 2.5 J higher, then the heat absorbed during the process is 
 
  (a) 15 J   (b) 17.5 J  (c) 20 J   (d) 22.5 J 
Q 17.  A gas can expand through two processes : (i) isobaric, (ii) P/V = constant. Assuming that the 
initial volume is same in both processes and the final volume which is two times the initial volume 
is also same in both processes, which of the following is true? 
  (a) Work done by gas in process (i) is greater than the work done by the gas in process (ii) 
  (b) Work done by gas in process (i) is smaller than the work done by the gas in process (ii) 
  (c) Final pressure is greater in process (i) 
  (d) Final temperature is greater in process (i) 
Q 18.  The cyclic process form a circle on a PV diagram as shown in figure. The work done by the gas is 
 
 (a) 
2
21
(P P )
4
?
?  (b) 
2
21
(V V )
4
?
? (c) 
2 1 2 1
(P P )(V V )
2
?
??  (d) 
2 1 2 1
(P P )(V V )
4
?
?? 
Q 19.  The equation of a state of a gas is given by P(V - b) = nRT. If 1 mole of a gas is isothermally 
expanded from volume V and 2 V, the work done during the process is 
 (a) 
2V b
RTln
Vb
?
?
 (b) 
Vb
RT ln
V
?
 (c) 
Vb
RTln
2V b
?
?
 (d) 
V
RT ln
Vb ?
 
Q 20.  A cyclic process for 1 mole of an ideal gas is shown in the V- T diagram. The work done in AB, 
BC and CA respectively is 
 
 (a) 
2
2 1 2
1
V
0,RT ln ,R(T T )
V
?    (b) 
1
1 2 1
2
V
R(T T ),0,RT ln
V
? 
  (c) 
1
1 1 2
2
V
0,RT ln ,R(T T )
V
?   (d) 
2
2 2 1
1
V
0,RT ln ,R(T T )
V
?  
Q 21.  An ideal gas of adiabatic exponent is expanded so that the amount of heat transferred to the gas is 
equal to the decrease of its internal energy. Then the equation of the process in terms of the 
variables T and V is 
 (a) 
( 1)
2
TV C
??
?  (b) 
( 2)
2
TV C
??
? (c) 
( 1)
4
TV C
??
? (d) 
( 2)
4
TV C
??
? 
Q 22.  A thermodynamical process is shown in the figure with PA = 3 × Patm ,VA =2 × 10
-4
 m
3
 ,PB = 8 × 
Patm, VC = 5 × 10
-4
 m
3
. In the process AB and BC, 600 J and 200 J heat are added to the system. 
Find the change in internal energy of the system in the process CA. [1Patm = 10
5
 N/m
2
 ] 
 
  (a) 560J   (b) -560J  (c) -240J   (d) +240J 
Q 23.  If WABC is the work done in process A ? B ? C and W DEF is work done in process D ? E ? F 
as shown in the figure, then 
 
  (a) |W DEF| > |WABC|  (b) |W DEF| < |WABC| (c) W DEF = WABC  (d) WDEF = - WABC 
Page 5


For JEE Advanced 
Objective Questions 
  Single Correct Option 
Q 1.  1 mole of an ideal gas is taken through a cyclic process. The minimum temperature during the 
cycle is 300 K. Then net exchange of heat for complete cycle is 
 
  (a) 600 R In 2   (b) 300 R In 2   (c)-300 R ln 2   (d) 900 R In 2 
Q 2.  Two moles of an ideal gas are undergone a cyclic process 1-2-3-1. If net heat exchange in the 
process is 300 J, the work done by the gas in the process 2-3 is 
 
  (a) -500 J   (b) – 5000 J   (c) – 3000 J   (d) None of these 
Q 3.  Two cylinders fitted with pistons contain equal amount of an ideal diatomic gas at 300 K. The 
piston of A is free to move, while that of B is held fixed. The same amount of heat is given to the 
gas in each cylinder. If the rise in temperature of the gas in A is 30 K, then the rise in temperature 
of gas in B is 
  (a) 30 K   (b) 18 K   (c) 50 K   (d) 42 K 
Q 4.  A gas follows a process TV
n-1
 = constant, where T = absolute temperature of the gas and V = 
volume of the gas. The bulk modulus of the gas in the process is given by 
  (a) (n - 1)P   (b) P/(n-1)   (c) nP    (d) P/n 
Q 5.  A cyclic process 1-2-3-4-1 is depicted on V-T diagram. The P-T and P-V diagrams for this cyclic 
process are given below. Select the correct choices (more than one options is/are correct) 
 
  (a)  (b) (c)  (d) None of these 
Q 6.  One mole of an ideal gas at temperature T1 expands slowly according to the law P/V - constant. Its 
final temperature is T2. The work done by the gas is 
  (a) R(T2 - T1)   (b) 2R(T2 - T1)  (c) 
21
R
(T T )
2
? (d) 
21
2R
(T T )
3
? 
Q 7.  In a process the pressure of an ideal gas is proportional to square of the volume of the gas. If the 
temperature of the gas increases in this process, then work done by this gas 
  (a) is positive   (b) is negative  (c) is zero   (d) may be positive or negative 
Q 8.  n moles of a gas are filled in a container at temperature T. If the gas is slowly and isothermally 
compressed to half its initial volume, the work done
 
by the atmosphere on the gas is 
 
 (a) 
nRT
2
   (b) 
nRT
2
?
  
(c) nRT ln 2   (d) - nRT ln 2 
Q 9.  600 J of heat is added to a monoatomic gas in a process in which the gas performs a work of 150 J. 
The molar heat capacity for the process is 
  (a) 3R    (b) 4R   (c) 2R    (d) 6R 
Q 10.  A gas undergoes A to B through three different processes 1, 2 and 3 as shown in the figure. The 
heat supplied to the gas is Q1, Q2 and Q3 respectively, then 
 
  (a) Q1 = Q2 = Q 3  (b) Q1 < Q2 < Q3 (c) Q1 > Q2 > Q 3  (d) Q1 = Q3 > Q2  
Q 11.  The internal energy of a gas is given by U = 2PV. It expands from V0 to 2V0 against a constant 
pressure P0. The heat absorbed by the gas in the process is 
  (a) 2P0V0   (b) 4P0V0   (c) 3P0V0   (d) P0V0 
Q 12.  For an adiabatic compression the quantity PV 
  (a) increases   (b) decreases   (c) remains constant  (d) depends on 
Q 13.  The figure shows two paths for the change of state of a gas from A to B. The ratio of molar heat 
capacities in path 1 and path 2 is 
 
  (a) < 1    (b) > 1   (c) 1    (d) Data insufficient 
Q 14.  P-T diagram of one mole of an ideal monoatomic gas is shown. Processes AB and CD are 
adiabatic. Work done in the complete cycle is 
/ 
  (a) 2.5 RT   (b) -2RT   (c) 1.5 RT   (d) -3.5 RT 
Q 15.  An ideal monoatomic gas undergoes a process in which its internal energy U and density ?
 
vary as
 
U ? 
= constant. The ratio of change in internal energy and the work done by the gas is 
 (a) 
3
2
    (b) 
2
3
    (c) 
1
3
    (d) 
3
5
  
Q 16.  The given figure shows the variation of force applied by ideal gas on a piston which undergoes a 
process during which piston position changes from 0.1 to 0.4 m. If the internal energy of the 
system at the end of the process is 2.5 J higher, then the heat absorbed during the process is 
 
  (a) 15 J   (b) 17.5 J  (c) 20 J   (d) 22.5 J 
Q 17.  A gas can expand through two processes : (i) isobaric, (ii) P/V = constant. Assuming that the 
initial volume is same in both processes and the final volume which is two times the initial volume 
is also same in both processes, which of the following is true? 
  (a) Work done by gas in process (i) is greater than the work done by the gas in process (ii) 
  (b) Work done by gas in process (i) is smaller than the work done by the gas in process (ii) 
  (c) Final pressure is greater in process (i) 
  (d) Final temperature is greater in process (i) 
Q 18.  The cyclic process form a circle on a PV diagram as shown in figure. The work done by the gas is 
 
 (a) 
2
21
(P P )
4
?
?  (b) 
2
21
(V V )
4
?
? (c) 
2 1 2 1
(P P )(V V )
2
?
??  (d) 
2 1 2 1
(P P )(V V )
4
?
?? 
Q 19.  The equation of a state of a gas is given by P(V - b) = nRT. If 1 mole of a gas is isothermally 
expanded from volume V and 2 V, the work done during the process is 
 (a) 
2V b
RTln
Vb
?
?
 (b) 
Vb
RT ln
V
?
 (c) 
Vb
RTln
2V b
?
?
 (d) 
V
RT ln
Vb ?
 
Q 20.  A cyclic process for 1 mole of an ideal gas is shown in the V- T diagram. The work done in AB, 
BC and CA respectively is 
 
 (a) 
2
2 1 2
1
V
0,RT ln ,R(T T )
V
?    (b) 
1
1 2 1
2
V
R(T T ),0,RT ln
V
? 
  (c) 
1
1 1 2
2
V
0,RT ln ,R(T T )
V
?   (d) 
2
2 2 1
1
V
0,RT ln ,R(T T )
V
?  
Q 21.  An ideal gas of adiabatic exponent is expanded so that the amount of heat transferred to the gas is 
equal to the decrease of its internal energy. Then the equation of the process in terms of the 
variables T and V is 
 (a) 
( 1)
2
TV C
??
?  (b) 
( 2)
2
TV C
??
? (c) 
( 1)
4
TV C
??
? (d) 
( 2)
4
TV C
??
? 
Q 22.  A thermodynamical process is shown in the figure with PA = 3 × Patm ,VA =2 × 10
-4
 m
3
 ,PB = 8 × 
Patm, VC = 5 × 10
-4
 m
3
. In the process AB and BC, 600 J and 200 J heat are added to the system. 
Find the change in internal energy of the system in the process CA. [1Patm = 10
5
 N/m
2
 ] 
 
  (a) 560J   (b) -560J  (c) -240J   (d) +240J 
Q 23.  If WABC is the work done in process A ? B ? C and W DEF is work done in process D ? E ? F 
as shown in the figure, then 
 
  (a) |W DEF| > |WABC|  (b) |W DEF| < |WABC| (c) W DEF = WABC  (d) WDEF = - WABC 
Q 24.  An ideal gas has initial volume V and pressure P. In doubling its volume the minimum work done 
will be in the process (of the given processes) 
  (a) isobaric process     (b) isothermal process 
  (c) adiabatic process     (d) same in all given processes 
Q 25.  Ten moles of a diatomic perfect gas are allowed to expand at constant pressure. The initial volume 
and temperature are V0 and T0 respectively. If 
0
7
RT
2
heat is transferred to the gas then the final 
volume and temperature are 
  (a) l.1 K0,l.1T0  (b) 0.9 V0, 0.9T0 (c) 1.1 V0, 
0
10
T
11
  (d) 0.9V0, 
0
10
T
9
 
Q 26.  An ideal monoatomic gas is carried around the cycle ABCDA as shown in the figure. The 
efficiency of the gas cycle is 
 
 (a) 
4
21
   (b) 
2
21
   (c) 
4
31
   (d) 
2
31
 
Q 27.  A gas takes part in two processes in which it is heated from the same initial state 1 to the same 
final temperature. The processes are shown on the P-V diagram by the straight lines 1-3 and 1-2.2 
and 3 are the points on the same isothermal curve. Q1 and Q2 are the heat transfer along the two 
processes. Then 
 
  (a) Q1 = Q2   (b) Q1 < Q2   (c) Q1 > Q2   (d) Insufficient data 
Q 28.  In the process shown in figure, the internal energy of an ideal gas decreases by 
00
3P V
2
in going 
from point C to A. Heat transfer along the process CA is 
 
  (a) (-3P0V0)  (b) (-5P0V 0/2)   (c) (-3P0V0/2)   (d) zero