NEET-UG SERIES Chemistry
Thermodynamics
65 previous year questions.
Volume: 65 Ques
Yield: High
High-Yield Trend
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2008 Chapter Questions 65 MCQs
01
PYQ 1990
medium
chemistry ID: neet-ug-
If is the change in enthalpy and , the change in internal energy accompanying a gaseous reaction, then
1
is always greater than
2
only if the number of moles of the products is greater than the number of moles of the reactants
3
is always less than
4
only if the number of moles of products is less than the number of moles of the reactants
02
PYQ 1994
medium
chemistry ID: neet-ug-
During isothermal expansion of an ideal gas, its
1
internal energy increases
2
enthalpy increases
3
enthalpy reduces to zero
4
enthalpy remains unchanged.
03
PYQ 1995
medium
chemistry ID: neet-ug-
If enthalpies of formation for and at and pressure are and - respectively, then enthalpy of combustion of will be
1
- 141.2 kJ/mol
2
#ERROR!
3
#ERROR!
4
- 1412 kJ/mol
04
PYQ 1995
easy
chemistry ID: neet-ug-
A reaction occurs spontaneously if :
1
and both and are +ve
2
and both and are +ve
3
and both and are +ve
4
and is + ve and is -ve
05
PYQ 1996
medium
chemistry ID: neet-ug-
Which of the following is the correct equation?
1
?U = ?W + ?Q
2
?U = ?Q - W
3
?W = ?U + ?Q
4
None of these
06
PYQ 2000
medium
chemistry ID: neet-ug-
Cell reaction is spontaneous when
1
is negative
2
is positive
3
is negative
4
is positive
07
PYQ 2000
medium
chemistry ID: neet-ug-
For the reaction which one is true:
1
2
3
>
4
08
PYQ 2000
medium
chemistry ID: neet-ug-
At latent heat of fusion of a compound is . Entropy change is:
1
2
3
4
09
PYQ 2000
medium
chemistry ID: neet-ug-
1
2
3
4
10
PYQ 2001
hard
chemistry ID: neet-ug-
Enthalpy of CH4+ O2 CH3OH is negative. If enthalpy of combustion of CH4 and CH3OH are x and y respectively. Then which relation is correct : -
1
x>y
2
x
3
x=y
4
x y
11
PYQ 2001
easy
chemistry ID: neet-ug-
Change in enthalpy for reaction 2H2O2(l) → 2H2O(l) + O2(g) If heat of formation of H2O2(l) and H2O(l) are – 188 & – 286 KJ/mol respectively : -
1
-196 KJ/mol
2
(+196 KJ/mol)
3
(+198 KJ/mol)
4
-198 KJ/mol
12
PYQ 2001
easy
chemistry ID: neet-ug-
When 1 mol gas is heated at constant volume temp. is raised from 298 to 308 K. Heat supplied to the gas is 500 J. Then which statement is correct : -
1
q = w = 500 J, ∆U = 0
2
q = ∆U = 500J, w = 0
3
q = w = 500 J, ∆U = 0
4
∆U = 0, q = w = – 500 J
13
PYQ 2002
medium
chemistry ID: neet-ug-
In a closed insulated container a liquid is stirred with a paddle to increase the temperature which of the following is true : -
1
2
3
4
14
PYQ 2002
medium
chemistry ID: neet-ug-
Heat of combustion for and are -94,-68 and then for is:-
1
- 17 Kcal
2
- 111 Kcal
3
- 170 Kcal
4
- 85 Kcal
15
PYQ 2002
medium
chemistry ID: neet-ug-
Unit of entropy is : -
1
2
3
4
16
PYQ 2002
medium
chemistry ID: neet-ug-
Unit of entropy is
1
JK–1 mol–1
2
J mol–1
3
J–1K–1 mol–1 v
4
JK mol–1
17
PYQ 2002
medium
chemistry ID: neet-ug-
2 mole of ideal gas at 27ºC temp. is expanded reversibly from 2 lit. to 20 lit. Find entropy change (R = 2 cal/mol K)
1
92.1
2
0
3
4
4
9.2
18
PYQ 2003
easy
chemistry ID: neet-ug-
The molar heat capacity of water at constant pressure, C, is 75 JK–1mol–1. When 1.0 KJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is:
1
1.2 K
2
2.4 K
3
4.8 K
4
6.6 K
19
PYQ 2003
medium
chemistry ID: neet-ug-
What is the entropy change (in ) when one mole of ice is converted into water at ?(The enthalpy change for the conversion of ice to liquid water is at )
1
21.98
2
20.13
3
2.013
4
2.198
20
PYQ 2003
medium
chemistry ID: neet-ug-
Formation of a solution from two components can be considered as : (i) Pure solvent separated solvent molecules, (ii) Pure solvent separated solvent molecules, (iii) Separated solvent and solute molecules solution, Solution so formed will be ideal if
1
2
3
4
21
PYQ 2003
medium
chemistry ID: neet-ug-
For which one of the following equations is ∆Hºreact equal to ∆Hºf for the product:
1
2
3
4
22
PYQ 2004
medium
chemistry ID: neet-ug-
The solubility product of a sparingly soluble salt AX2 is 3.2 ×10–11. Its solubility (in moles/liter) is
1
3.1×10–4
2
2 × 10–4
3
4 × 10–4
4
5.6 × 10–6
23
PYQ 2004
medium
chemistry ID: neet-ug-
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
–608 J
2
+ 304 J
3
–304 J
4
–6 J
24
PYQ 2004
medium
chemistry ID: neet-ug-
The standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are –382.64 kJ mol–1 and –145.6 JK–1 mol–1, respectively. Standard Gibbs energy change for the same reaction at 298 K is
1
–339.3 kJ mol–1
2
– 439.3 kJ mol–1
3
–523.2 kJ mol–1
4
–221.1 kJ mol–1
25
PYQ 2004
medium
chemistry ID: neet-ug-
If the bond energies of H–H, Br – Br and H –Br are 433, 192 and 364 kJ mol–1 respectively the ∆Hº for the reaction H2(g) + Br2(g) 2HBr(g)
1
+ 103 kJ
2
261kJ
3
–103 kJ
4
–261 kJ
26
PYQ 2004
easy
chemistry ID: neet-ug-
Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is
1
∆Ssystem – ∆Ssurrounding > 0
2
∆Ssystem > 0 only (3) ∆Ssurroundings > O on
3
∆Ssurrounding > 0
4
∆Ssystem + ∆Ssurrounding > 0
27
PYQ 2005
easy
chemistry ID: neet-ug-
Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?
1
Exothermic and decreasing disorder
2
Endothermic and increasing disorder
3
Exothermic and increasing disorder
4
Endothermic and decreasing disorder
28
PYQ 2005
medium
chemistry ID: neet-ug-
At 25°C,the dissociation constant of a base, BOH, is 1.0 x 10-12. The concentration of hydroxyl ions in 0.01 M aqueous solution of the base would be:
1
1.0 x 10-6 mol L-1
2
1.0 x 10-5 mol L-1
3
1.0 x 10-8 mol L-1
4
1.0 x 10-7 mol L-1
29
PYQ 2005
easy
chemistry ID: neet-ug-
A reaction occurs spontaneously if:
30
PYQ 2005
easy
chemistry ID: neet-ug-
The absolute enthalpy of neutralisation of the reaction: MgO(s)+2HCl(aq) MgCl2(aq)+H2O (l) will be:
31
PYQ 2006
medium
chemistry ID: neet-ug-
The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexene (C6H12) are -241, -3800 and -3920 kJ per mol respectively. Heat of hydrogenation of cyclohexene is:
1
-121 kJ per mol
2
+121 kJ per mol
3
+484 kJ per mol
4
-484 kJ per mol
32
PYQ 2006
medium
chemistry ID: neet-ug-
Assume each reaction is carried out in an open container. For which reaction will ∆H = ∆E?
1
H2(g) + Br2(g) 2HBr(g)
2
C(s) + 2H2O(g) 2H2(g) + CO2(g)
3
PCl5(g) PCl3(g) + Cl2(g)
4
2CO(g) + O2(g) 2CO2(g)
33
PYQ 2006
medium
chemistry ID: neet-ug-
The enthalpy and entropy change for the reaction : are and respectively. The temperature at which the reaction will be in equilibrium is :
1
285.7 K
2
373 K
3
250 K
4
400 K
34
PYQ 2006
medium
chemistry ID: neet-ug-
Identify the correct statement for change of Gibbs energy for a system ( ) at constant temperature and pressure :
1
If , the process is spontaneous
2
If , the system has attained equilibrium
3
If , the system is still moving in a particular direction
4
If $\Delta G_{\text{system}}
35
PYQ 2008
medium
chemistry ID: neet-ug-
Which of the following are not state functions? (I) q + W (II) q (III) w (IV) H-TS
1
(II) and (III)
2
(I) and (IV)
3
(II), (III) and (IV)
4
(I), (II) and (III)
36
PYQ 2008
medium
chemistry ID: neet-ug-
Bond dissociation enthalpy of and are and respectively. Enthalpy of formation of is
1
2
3
4
37
PYQ 2008
medium
chemistry ID: neet-ug-
For the gas phase reaction, which of the following conditions are correct ?
1
2
3
4
38
PYQ 2009
medium
chemistry ID: neet-ug-
From the following bond energies : bond energy bond energy bond energy bond energy Enthalpy for the reaction, will be
1
2
3
4
39
PYQ 2010
medium
chemistry ID: neet-ug-
Three moles of an ideal gas expanded spontaneously into vaccum. The work done will be
1
3 Joules
2
9 Joules
3
Zero
4
Infinite
40
PYQ 2010
easy
chemistry ID: neet-ug-
The following two reactions are known The value of for the following reaction is
1
- 43.3 kJ
2
-10.3 kJ
3
+6.2 kJ
4
+10.3 kJ
41
PYQ 2011
medium
chemistry ID: neet-ug-
Consider the following processes : ½ A → B + 150 3B → 2C + D -125 E + A → 2D +350 For B + D → E + 2C, ΔH will be-
1
325 kJ/mol
2
525 kJ/mol
3
-175 kJ.mol
4
-325 kJ/mol
42
PYQ 2011
medium
chemistry ID: neet-ug-
Which of the following is correct option for free expansion of an ideal gas under adiabatic condition ?
1
2
3
4
43
PYQ 2011
easy
chemistry ID: neet-ug-
Enthalpy change for the reaction, is The dissociation energy of bond is
1
- 434.8 kJ
2
- 869.6 kJ
3
#ERROR!
4
#ERROR!
44
PYQ 2012
medium
chemistry ID: neet-ug-
The enthalpy of fusion of water is The molar entropy change for the melting of ice at is :
1
5.260cal /(molK)
2
0.526cal /(molK)
3
10.52 cal /(molK)
4
21.04 cal /(molK)
45
PYQ 2013
easy
chemistry ID: neet-ug-
A reaction having equal energies of activation for forward and reverse reactions has :-
1
2
3
4
46
PYQ 2014
medium
chemistry ID: neet-ug-
For the reaction:
△U = 2.1 k cal, △S = 20 cal K–l at 300 K.
Hence △G is
△U = 2.1 k cal, △S = 20 cal K–l at 300 K.
Hence △G is
1
–2.7 k cal
2
9.3 k cal
3
-9.3 k cal
4
2.7 k cal
47
PYQ 2014
medium
chemistry ID: neet-ug-
Using the Gibbs energy change, , for the following reaction,
the of (s) in water at is :
the of (s) in water at is :
1
2
3
4
48
PYQ 2014
medium
chemistry ID: neet-ug-
Which of the following statements is correct for the spontaneous adsorption of a gas?
1
is negative and therefore, should be highly positive
2
is negative and therefore, should be highly negative
3
is positive and therefore, should be negative
4
is positive and therefore, should also be highly positive
49
PYQ 2016
medium
chemistry ID: neet-ug-
Consider the following liquid-vapour equilibrium Which of the following relations is correct ?
1
2
3
4
50
PYQ 2016
medium
chemistry ID: neet-ug-
For a sample of perfect gas when its pressure is changed isothermally from to , the entropy change is given by
1
2
3
4
51
PYQ 2017
medium
chemistry ID: neet-ug-
A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy △U of the gas in joules will be
1
1136.25 J
2
- 500 J
3
–505 J
4
+505 J
52
PYQ 2017
medium
chemistry ID: neet-ug-
For a given reaction, △H = 35.5 kJ mol–1 and △S = 83.6 JK–1 mol–1. The reaction is spontaneous at :
(Assume that△H and △S do not vary with temperature)
(Assume that△H and △S do not vary with temperature)
1
T < 425 K
2
T > 425 K
3
All temperatures
4
T > 298 K
53
PYQ 2017
medium
chemistry ID: neet-ug-
For a given reaction, and The reaction is spontaneous
at (Assume that and do not vary with temperature)
1
T > 425 K
2
All temperatures
3
T > 298 K
4
T < 425 K
54
PYQ 2017
medium
chemistry ID: neet-ug-
A gas is allowed to expand in a well insulated container against a constant external pressure of from an initial volume of to a final volume of . The change in internal energy of the gas in joules will be
1
-500J
2
-505J
3
#ERROR!
4
1136.25J
55
PYQ 2019
easy
chemistry ID: neet-ug-
Under isothermal condition, a gas at 300 K expands from 0.1 L to 0.25 L against a constant externalpressureof2bar Theworkdonebythe gas i s : [Given that 1Lbar= 100J)
1
25 J
2
30 J
3
- 30J
4
5 kJ
56
PYQ 2019
easy
chemistry ID: neet-ug-
In which case change in entropy is negative ?
1
Sublimation of solid to gas
2
3
Evaporation of water
4
Expansion ofa gas at constant temperature
57
PYQ 2021
medium
chemistry ID: neet-ug-
The maximum temperature that can be achieved
in blast furnace is :
1
upto 1200 K
2
upto 2200 K
3
upto 1900 K
4
upto 5000 K
58
PYQ 2022
medium
chemistry ID: neet-ug-
Which of the following p-V curve represents maximum work done?
1
2
3
4
59
PYQ 2023
hard
chemistry ID: neet-ug-
The right option for the mass of CO2 produced by heating 20g of 20% pure limestone is
(Atomic mass of Ca= 40)
(Atomic mass of Ca= 40)
1
1.76 g
2
2.64 g
3
1.32 g
4
1.12 g
60
PYQ 2023
medium
chemistry ID: neet-ug-
Which amongst the following options is the correct relation between change in enthalpy and change in internal energy
1
2
3
4
61
PYQ 2024
medium
chemistry ID: neet-ug-
For the following reaction at 300 K: The enthalpy change is , then the internal energy change is:
1
19988.4 J
2
200 J
3
1999 J
4
1.9988 kJ
62
PYQ 2024
medium
chemistry ID: neet-ug-
For an endothermic reaction:
(A) is negative.
(B) is positive.
(C) is negative.
(D) is positive.
Choose the correct answer from the options given below:
(A) is negative.
(B) is positive.
(C) is negative.
(D) is positive.
Choose the correct answer from the options given below:
1
B and D
2
C and D
3
A and B
4
A and C
63
PYQ 2024
medium
chemistry ID: neet-ug-
Choose the correct statement for the work done in the expansion and heat absorbed or released when 5 litres of an ideal gas at 10 atmospheric pressure isothermally expands into vacuum until volume is 15 litres :
1
Both the heat and work done will be greater than zero
2
Heat absorbed will be less than zero and work done will be positive
3
Work done will be zero and heat will also be zero
4
Work done will be greater than zero and heat will remain zero
64
PYQ 2024
medium
chemistry ID: neet-ug-
Match List I with List II
Choose the correct answer from the options given below:
List-I | List-II | ||
| (A) | Isothermal process | (I) | No heat exchange |
| (B) | Isochoric process | (II) | Carried out at constant temperature |
| (C) | Isobaric process | (III) | Carried out at constant volume |
| (D) | Adiabatic process | (IV) | Carried out at constant pressure |
Choose the correct answer from the options given below:
1
A-IV, B-III, C-II, D-I
2
A-IV, B-II, C-III, D-I
3
A-I, B-II, C-III, D-IV
4
A-II, B-III, C-IV, D-I
65
PYQ 2025
medium
chemistry ID: neet-ug-
The standard heat of formation, in kcal/mol, of is:
Given: Standard heat of formation of SO₄²⁻(aq) = -216 kcal/mol, standard heat of crystallization of BaSO₄(s) = -4.5 kcal/mol, standard heat of formation of BaSO₄(s) = -349 kcal/mol.
1
133.0
2
133.0 + 133.0
3
220.5
4
-128.5