Thermodynamics: JEE Mains Previous Year Questions (2021-2024) | Chemistry for JEE Main & Advanced PDF Download

 Page 1


 
 
2024 
 
Q1 - 2024 (01 Feb Shift 1) 
Choose the correct option for free expansion of an ideal gas under adiabatic condition 
from the following : 
(1) ?? = 0,??? ? 0,?? = 0 
(2) ?? = 0,??? < 0,?? ? 0 
(3) ?? ? 0,??? = 0,?? = 0 
(4) ?? = 0,??? = 0,?? = 0 
 
Q2 - 2024 (01 Feb Shift 2) 
For a certain reaction at 300K, K = 10, then ?G
°
 for the same reaction is ____ ×
10
-1
kJmol
-1
. (Given R = 8.314JK
-1
mol
-1
) 
 
Q3 - 2024 (27 Jan Shift 1) 
If three moles of an ideal gas at 300K expand isotherrnally from 30dm
3
 to 45dm
3
 against 
a constant opposing pressure of 80kPa, then the amount of heat transferred is _____ J. 
 
Q4 - 2024 (27 Jan Shift 2) 
For a certain thermochemical reaction M ? N at T = 400K,?H
?
= 77.2kJmol
-1
,?S =
122JK
-1
, log equilibrium constant (log? K)is  _____ × 10
-1
. 
 
Q5 - 2024 (29 Jan Shift 1) 
Which of the following is not correct? 
(1) ?G is negative for a spontaneous reaction 
(2) ?G is positive for a spontaneous reaction 
(3) ?G is zero for a reversible reaction 
(4) ?G is positive for a non-spontaneous reaction 
 
Q6 - 2024 (29 Jan Shift 2) 
Page 2


 
 
2024 
 
Q1 - 2024 (01 Feb Shift 1) 
Choose the correct option for free expansion of an ideal gas under adiabatic condition 
from the following : 
(1) ?? = 0,??? ? 0,?? = 0 
(2) ?? = 0,??? < 0,?? ? 0 
(3) ?? ? 0,??? = 0,?? = 0 
(4) ?? = 0,??? = 0,?? = 0 
 
Q2 - 2024 (01 Feb Shift 2) 
For a certain reaction at 300K, K = 10, then ?G
°
 for the same reaction is ____ ×
10
-1
kJmol
-1
. (Given R = 8.314JK
-1
mol
-1
) 
 
Q3 - 2024 (27 Jan Shift 1) 
If three moles of an ideal gas at 300K expand isotherrnally from 30dm
3
 to 45dm
3
 against 
a constant opposing pressure of 80kPa, then the amount of heat transferred is _____ J. 
 
Q4 - 2024 (27 Jan Shift 2) 
For a certain thermochemical reaction M ? N at T = 400K,?H
?
= 77.2kJmol
-1
,?S =
122JK
-1
, log equilibrium constant (log? K)is  _____ × 10
-1
. 
 
Q5 - 2024 (29 Jan Shift 1) 
Which of the following is not correct? 
(1) ?G is negative for a spontaneous reaction 
(2) ?G is positive for a spontaneous reaction 
(3) ?G is zero for a reversible reaction 
(4) ?G is positive for a non-spontaneous reaction 
 
Q6 - 2024 (29 Jan Shift 2) 
Standard enthalpy of vapourisation for CCl
4
 is 30.5kJmol
-1
. Heat required for 
vapourisation of 284g of CCl
4
 at constant temperature is ____ kJ. 
(Given molar mass in gmol
-1
; C = 12, Cl = 35.5) 
 
Q7 - 2024 (30 Jan Shift 1) 
 
An ideal gas undergoes a cyclic transformation starting from the point ?? and coming 
back to the same point by tracing the path A ? B ? C ? A as shown in the diagram. The 
total work done in the process is ______ J. 
 
Q8 - 2024 (30 Jan Shift 2) 
Two reactions are given below: 
2Fe
(s)
+
3
2
O
2(g)
? Fe
2
O
3(s)
,?H
°
= -822kJ/mol 
C
(s)
+
1
2
O
2(g)
? CO
(g)
,?H
°
= -110kJ/mol 
Then enthalpy change for following reaction 
3C
(s)
+ Fe
2
O
3(s)
? 2Fe
(s)
+ 3CO
(g)
 
 
Q9 - 2024 (31 Jan Shift 1) 
Consider the following reaction at 298K. 
3
2
O
2(g)
? O
3(g)
· K
P
= 2.47 × 10
-29
. 
?
r
G
?
 for the reaction is kJ. (Given R = 8.314JK
-1
mol
-1
) 
 
Q10 - 2024 (31 Jan Shift 2) 
If 5 moles of an ideal gas expands from 10L to a volume of 100L at 300K under 
isothermal and reversible condition then work, w, is -?? J. The value of ?? is  ____ 
(Given R = 8.314JK
-1
mol
-1
) 
 
Answer Key 
Page 3


 
 
2024 
 
Q1 - 2024 (01 Feb Shift 1) 
Choose the correct option for free expansion of an ideal gas under adiabatic condition 
from the following : 
(1) ?? = 0,??? ? 0,?? = 0 
(2) ?? = 0,??? < 0,?? ? 0 
(3) ?? ? 0,??? = 0,?? = 0 
(4) ?? = 0,??? = 0,?? = 0 
 
Q2 - 2024 (01 Feb Shift 2) 
For a certain reaction at 300K, K = 10, then ?G
°
 for the same reaction is ____ ×
10
-1
kJmol
-1
. (Given R = 8.314JK
-1
mol
-1
) 
 
Q3 - 2024 (27 Jan Shift 1) 
If three moles of an ideal gas at 300K expand isotherrnally from 30dm
3
 to 45dm
3
 against 
a constant opposing pressure of 80kPa, then the amount of heat transferred is _____ J. 
 
Q4 - 2024 (27 Jan Shift 2) 
For a certain thermochemical reaction M ? N at T = 400K,?H
?
= 77.2kJmol
-1
,?S =
122JK
-1
, log equilibrium constant (log? K)is  _____ × 10
-1
. 
 
Q5 - 2024 (29 Jan Shift 1) 
Which of the following is not correct? 
(1) ?G is negative for a spontaneous reaction 
(2) ?G is positive for a spontaneous reaction 
(3) ?G is zero for a reversible reaction 
(4) ?G is positive for a non-spontaneous reaction 
 
Q6 - 2024 (29 Jan Shift 2) 
Standard enthalpy of vapourisation for CCl
4
 is 30.5kJmol
-1
. Heat required for 
vapourisation of 284g of CCl
4
 at constant temperature is ____ kJ. 
(Given molar mass in gmol
-1
; C = 12, Cl = 35.5) 
 
Q7 - 2024 (30 Jan Shift 1) 
 
An ideal gas undergoes a cyclic transformation starting from the point ?? and coming 
back to the same point by tracing the path A ? B ? C ? A as shown in the diagram. The 
total work done in the process is ______ J. 
 
Q8 - 2024 (30 Jan Shift 2) 
Two reactions are given below: 
2Fe
(s)
+
3
2
O
2(g)
? Fe
2
O
3(s)
,?H
°
= -822kJ/mol 
C
(s)
+
1
2
O
2(g)
? CO
(g)
,?H
°
= -110kJ/mol 
Then enthalpy change for following reaction 
3C
(s)
+ Fe
2
O
3(s)
? 2Fe
(s)
+ 3CO
(g)
 
 
Q9 - 2024 (31 Jan Shift 1) 
Consider the following reaction at 298K. 
3
2
O
2(g)
? O
3(g)
· K
P
= 2.47 × 10
-29
. 
?
r
G
?
 for the reaction is kJ. (Given R = 8.314JK
-1
mol
-1
) 
 
Q10 - 2024 (31 Jan Shift 2) 
If 5 moles of an ideal gas expands from 10L to a volume of 100L at 300K under 
isothermal and reversible condition then work, w, is -?? J. The value of ?? is  ____ 
(Given R = 8.314JK
-1
mol
-1
) 
 
Answer Key 
Q1 (4)  
 
Q2 (57)  
 
Q3 (1200)  
 
Q4 (37)  
 
Q5 (2)  
 
Q6 (56)  
 
Q7 (200)  
 
Q8 (492)  
 
Q9 (163)  
 
Q10 (28721) 
 
 
Solutions 
Q1 
During free expansion of an ideal gas under adiabatic condition q = 0,?T = 0, w = 0. 
 
Q2 
?G
°
= -RTlnK 
= -8.314 × 300ln? (10) 
= 5744.14J/mole 
= 57.44 × 10
-1
kJ/mole 
 
Q3 
Using, first law of thermodynamics, 
?U = Q + W, 
?U = 0 : Process is isothermal 
Q = -W 
W = -P
ext 
?V: Irreversible 
= -80 × 10
3
(45 - 30) × 10
-3
 
Page 4


 
 
2024 
 
Q1 - 2024 (01 Feb Shift 1) 
Choose the correct option for free expansion of an ideal gas under adiabatic condition 
from the following : 
(1) ?? = 0,??? ? 0,?? = 0 
(2) ?? = 0,??? < 0,?? ? 0 
(3) ?? ? 0,??? = 0,?? = 0 
(4) ?? = 0,??? = 0,?? = 0 
 
Q2 - 2024 (01 Feb Shift 2) 
For a certain reaction at 300K, K = 10, then ?G
°
 for the same reaction is ____ ×
10
-1
kJmol
-1
. (Given R = 8.314JK
-1
mol
-1
) 
 
Q3 - 2024 (27 Jan Shift 1) 
If three moles of an ideal gas at 300K expand isotherrnally from 30dm
3
 to 45dm
3
 against 
a constant opposing pressure of 80kPa, then the amount of heat transferred is _____ J. 
 
Q4 - 2024 (27 Jan Shift 2) 
For a certain thermochemical reaction M ? N at T = 400K,?H
?
= 77.2kJmol
-1
,?S =
122JK
-1
, log equilibrium constant (log? K)is  _____ × 10
-1
. 
 
Q5 - 2024 (29 Jan Shift 1) 
Which of the following is not correct? 
(1) ?G is negative for a spontaneous reaction 
(2) ?G is positive for a spontaneous reaction 
(3) ?G is zero for a reversible reaction 
(4) ?G is positive for a non-spontaneous reaction 
 
Q6 - 2024 (29 Jan Shift 2) 
Standard enthalpy of vapourisation for CCl
4
 is 30.5kJmol
-1
. Heat required for 
vapourisation of 284g of CCl
4
 at constant temperature is ____ kJ. 
(Given molar mass in gmol
-1
; C = 12, Cl = 35.5) 
 
Q7 - 2024 (30 Jan Shift 1) 
 
An ideal gas undergoes a cyclic transformation starting from the point ?? and coming 
back to the same point by tracing the path A ? B ? C ? A as shown in the diagram. The 
total work done in the process is ______ J. 
 
Q8 - 2024 (30 Jan Shift 2) 
Two reactions are given below: 
2Fe
(s)
+
3
2
O
2(g)
? Fe
2
O
3(s)
,?H
°
= -822kJ/mol 
C
(s)
+
1
2
O
2(g)
? CO
(g)
,?H
°
= -110kJ/mol 
Then enthalpy change for following reaction 
3C
(s)
+ Fe
2
O
3(s)
? 2Fe
(s)
+ 3CO
(g)
 
 
Q9 - 2024 (31 Jan Shift 1) 
Consider the following reaction at 298K. 
3
2
O
2(g)
? O
3(g)
· K
P
= 2.47 × 10
-29
. 
?
r
G
?
 for the reaction is kJ. (Given R = 8.314JK
-1
mol
-1
) 
 
Q10 - 2024 (31 Jan Shift 2) 
If 5 moles of an ideal gas expands from 10L to a volume of 100L at 300K under 
isothermal and reversible condition then work, w, is -?? J. The value of ?? is  ____ 
(Given R = 8.314JK
-1
mol
-1
) 
 
Answer Key 
Q1 (4)  
 
Q2 (57)  
 
Q3 (1200)  
 
Q4 (37)  
 
Q5 (2)  
 
Q6 (56)  
 
Q7 (200)  
 
Q8 (492)  
 
Q9 (163)  
 
Q10 (28721) 
 
 
Solutions 
Q1 
During free expansion of an ideal gas under adiabatic condition q = 0,?T = 0, w = 0. 
 
Q2 
?G
°
= -RTlnK 
= -8.314 × 300ln? (10) 
= 5744.14J/mole 
= 57.44 × 10
-1
kJ/mole 
 
Q3 
Using, first law of thermodynamics, 
?U = Q + W, 
?U = 0 : Process is isothermal 
Q = -W 
W = -P
ext 
?V: Irreversible 
= -80 × 10
3
(45 - 30) × 10
-3
 
= -1200J 
 
Q4 
?G
°
= ?H
°
- T?S
°
 
= 77.2 × 10
3
- 400 × 122 = 28400J 
?G
°
= -2.303RTlog? K 
? 28400 = -2.303 × 8.314 × 400log? K 
? log? K = -3.708 = -37.08 × 10
-1
 
 
Q5 
(?G)
P,T
= (+)ve for non-spontaneous process 
 
Q6 
?H
vap 
0
CCl
4
= 30.5kJ/mol 
Mass of CCl
4
= 284gm 
Molar mass of CCl
4
= 154g/mol 
Moles of CCl
4
=
284
154
= 1.844mol 
?H
vap 
°
for 1mole = 30.5kJ/mol 
?H
vap
°
for 1.844 mol = 30.5 × 1.844 
= 56.242kJ 
 
Q7 
rk done is given by area enclosed in the P vs V cyclic graph or V vs P cyclic graph. 
Sign of work is positive for clockwise cyclic process for V vs P graph. 
W =
1
2
× (30 - 10) × (30 - 10) = 200kPa - dm
3
= 200 × 1000Pa - L = 2L - bar = 200J
 
 
Q8 
2Fe
(s)
+
3
2
O
2(g)
? Fe
2
O
3(s)
,?H
°
= -822kJ/mol 
C
(s)
+
1
2
O
2(g)
? CO
(g)
,?H
°
= -110kJ/mol… 
3C
(s)
+ Fe
2
O
3(s)
? 2Fe
(s)
+ 3CO
(g)
,?H
3
= ? 
(3) = 3 × (2) - (1) 
Page 5


 
 
2024 
 
Q1 - 2024 (01 Feb Shift 1) 
Choose the correct option for free expansion of an ideal gas under adiabatic condition 
from the following : 
(1) ?? = 0,??? ? 0,?? = 0 
(2) ?? = 0,??? < 0,?? ? 0 
(3) ?? ? 0,??? = 0,?? = 0 
(4) ?? = 0,??? = 0,?? = 0 
 
Q2 - 2024 (01 Feb Shift 2) 
For a certain reaction at 300K, K = 10, then ?G
°
 for the same reaction is ____ ×
10
-1
kJmol
-1
. (Given R = 8.314JK
-1
mol
-1
) 
 
Q3 - 2024 (27 Jan Shift 1) 
If three moles of an ideal gas at 300K expand isotherrnally from 30dm
3
 to 45dm
3
 against 
a constant opposing pressure of 80kPa, then the amount of heat transferred is _____ J. 
 
Q4 - 2024 (27 Jan Shift 2) 
For a certain thermochemical reaction M ? N at T = 400K,?H
?
= 77.2kJmol
-1
,?S =
122JK
-1
, log equilibrium constant (log? K)is  _____ × 10
-1
. 
 
Q5 - 2024 (29 Jan Shift 1) 
Which of the following is not correct? 
(1) ?G is negative for a spontaneous reaction 
(2) ?G is positive for a spontaneous reaction 
(3) ?G is zero for a reversible reaction 
(4) ?G is positive for a non-spontaneous reaction 
 
Q6 - 2024 (29 Jan Shift 2) 
Standard enthalpy of vapourisation for CCl
4
 is 30.5kJmol
-1
. Heat required for 
vapourisation of 284g of CCl
4
 at constant temperature is ____ kJ. 
(Given molar mass in gmol
-1
; C = 12, Cl = 35.5) 
 
Q7 - 2024 (30 Jan Shift 1) 
 
An ideal gas undergoes a cyclic transformation starting from the point ?? and coming 
back to the same point by tracing the path A ? B ? C ? A as shown in the diagram. The 
total work done in the process is ______ J. 
 
Q8 - 2024 (30 Jan Shift 2) 
Two reactions are given below: 
2Fe
(s)
+
3
2
O
2(g)
? Fe
2
O
3(s)
,?H
°
= -822kJ/mol 
C
(s)
+
1
2
O
2(g)
? CO
(g)
,?H
°
= -110kJ/mol 
Then enthalpy change for following reaction 
3C
(s)
+ Fe
2
O
3(s)
? 2Fe
(s)
+ 3CO
(g)
 
 
Q9 - 2024 (31 Jan Shift 1) 
Consider the following reaction at 298K. 
3
2
O
2(g)
? O
3(g)
· K
P
= 2.47 × 10
-29
. 
?
r
G
?
 for the reaction is kJ. (Given R = 8.314JK
-1
mol
-1
) 
 
Q10 - 2024 (31 Jan Shift 2) 
If 5 moles of an ideal gas expands from 10L to a volume of 100L at 300K under 
isothermal and reversible condition then work, w, is -?? J. The value of ?? is  ____ 
(Given R = 8.314JK
-1
mol
-1
) 
 
Answer Key 
Q1 (4)  
 
Q2 (57)  
 
Q3 (1200)  
 
Q4 (37)  
 
Q5 (2)  
 
Q6 (56)  
 
Q7 (200)  
 
Q8 (492)  
 
Q9 (163)  
 
Q10 (28721) 
 
 
Solutions 
Q1 
During free expansion of an ideal gas under adiabatic condition q = 0,?T = 0, w = 0. 
 
Q2 
?G
°
= -RTlnK 
= -8.314 × 300ln? (10) 
= 5744.14J/mole 
= 57.44 × 10
-1
kJ/mole 
 
Q3 
Using, first law of thermodynamics, 
?U = Q + W, 
?U = 0 : Process is isothermal 
Q = -W 
W = -P
ext 
?V: Irreversible 
= -80 × 10
3
(45 - 30) × 10
-3
 
= -1200J 
 
Q4 
?G
°
= ?H
°
- T?S
°
 
= 77.2 × 10
3
- 400 × 122 = 28400J 
?G
°
= -2.303RTlog? K 
? 28400 = -2.303 × 8.314 × 400log? K 
? log? K = -3.708 = -37.08 × 10
-1
 
 
Q5 
(?G)
P,T
= (+)ve for non-spontaneous process 
 
Q6 
?H
vap 
0
CCl
4
= 30.5kJ/mol 
Mass of CCl
4
= 284gm 
Molar mass of CCl
4
= 154g/mol 
Moles of CCl
4
=
284
154
= 1.844mol 
?H
vap 
°
for 1mole = 30.5kJ/mol 
?H
vap
°
for 1.844 mol = 30.5 × 1.844 
= 56.242kJ 
 
Q7 
rk done is given by area enclosed in the P vs V cyclic graph or V vs P cyclic graph. 
Sign of work is positive for clockwise cyclic process for V vs P graph. 
W =
1
2
× (30 - 10) × (30 - 10) = 200kPa - dm
3
= 200 × 1000Pa - L = 2L - bar = 200J
 
 
Q8 
2Fe
(s)
+
3
2
O
2(g)
? Fe
2
O
3(s)
,?H
°
= -822kJ/mol 
C
(s)
+
1
2
O
2(g)
? CO
(g)
,?H
°
= -110kJ/mol… 
3C
(s)
+ Fe
2
O
3(s)
? 2Fe
(s)
+ 3CO
(g)
,?H
3
= ? 
(3) = 3 × (2) - (1) 
?H
3
= 3 × ?H
2
- ?H
1
 
= 3(-110) + 822 
= 492kJ/mole 
 
Q9 
3
2
O
2(g)
? O
3(g)
· K
p
= 2.47 × 10
-29
. 
?
r
G
?
= -RTln? K
P
 
= -8.314 × 10
-3
× 298 × ln? 2.47 × 10
-29
  
= -8.314 × 10
-3
× 298 × (-65.87) 
= 163.19kJ 
 
Q10 
It is isothermal reversible expansion, so work done negative 
W = -2.303nRTlog? 
V
2
V
1
 
= -2.303 × 5 × 8.314 × 300log? 
100
10
 
= -28720.713J
= -28721J