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Thermodynamics

83 Questions
All Exams NEET AIIMS
2008 NEET MCQ
AIPMT 2008
Bond dissociation enthalpy of H2, Cl2 and HCl are 434, 242 and 431 kJ mol$-$1 respectively. Enthalpy of formation of HCl is
A.
$-$ 93 kJ mol$-$1
B.
245 kJ mol$-$1
C.
93 kJ mol$-$1
D.
$-$ 245 kJ mol$-$1
2008 NEET MCQ
AIPMT 2008
Which of the following are not state functions ?
(I) q + w     (II) q
(III) w        (IV) H $-$ TS
A.
(I), (II) and (III)
B.
(II) and (III)
C.
(I) and (IV)
D.
(II), (III) and (IV)
2007 NEET MCQ
AIPMT 2007
Given that bond energies of H $-$ H and Cl $-$ Cl are 430 kJ mol$-$1 and 240 kJ mol$-$1 respectively and $\Delta $Hf for HCl is $-$ 90 kJ mol$-$1, bond enthalpy of HCl is
A.
380 kJ mol$-$1
B.
425 kJ mol$-$1
C.
245 kJ mol$-$1
D.
290 kJ mol$-$1
2007 NEET MCQ
AIPMT 2007
Consider the following reactions :
(i) H+(aq) + OH$-$(aq) = H2O(l),  $\Delta $H = $-$ X1 kJ mol$-$1
(ii) H2(g) + 1/2O2(g) = H2O(l),   $\Delta $H = $-$ X2 kJ mol$-$1
(iii) CO2(g) + H2(g) = CO(g) + H2O(l),  $\Delta $H = $-$ X3 kJ mol$-$1
(iv) C2H2(g) + 5/2O2(g) = 2CO2(g) + H2O(l),    $\Delta $H = +X4 kJ mol$-$1

Enthalpy of formation of H2O(l) is
A.
+X3 kJ mol$-$1
B.
$-$X4 kJ mol$-$1
C.
+X1 kJ mol$-$1
D.
$-$X2 kJ mol$-$1
2006 NEET MCQ
AIPMT 2006
Assume each reaction is carried out in an open container. For which reaction will $\Delta $H = $\Delta $E ?
A.
2CO(g) + O2(g) $ \to $  2CO2(g)
B.
H2(g) + Br2(g) $ \to $ 2HBr(g)
C.
C(s) + 2H2O(g) $ \to $ 2H2(g) + CO2(g)
D.
PCl5(g) $ \to $ PCl3(g) + Cl2(g)
2006 NEET MCQ
AIPMT 2006
The enthalpy of hydrogenation of cyclohexene is is $-$ 119.5 kJ mol$-$1. If resonance energy of benzene is $-$ 150.4 kJ mol$-$1, its enthalpy of hydrogenation would be
A.
$-$ 358.5 kJ mol$-$1
B.
$-$ 508.9 kJ mol$-$1
C.
$-$ 208.1 kJ mol$-$1
D.
$-$ 269.9 kJ mol$-$1
2006 NEET MCQ
AIPMT 2006
The enthalpy and entropy change for the reaction:
Br2(l) + Cl2(g) $ \to $ 2BrCl(g)
are 30 kJ mol$-$1 and 105 J K$-$1 mol$-$1 respectively.
The temperature at which the reaction will be in equilibrium is
A.
300 K
B.
285.7 K
C.
273 K
D.
450 K
2006 NEET MCQ
AIPMT 2006
Identify the correct statement for change of Gibb's energy for a system ($\Delta $Gsystem) at constant temperature and pressure.
A.
If $\Delta $Gsystem < 0, the process is not spontaneous.
B.
If $\Delta $Gsystem > 0, the process is spontaneous.
C.
If $\Delta $Gsystem = 0, the system has attained equilibrium.
D.
If $\Delta $Gsystem = 0, the system is till moving in a particular direction.
2005 NEET MCQ
AIPMT 2005
Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction ?
A.
Exothermic and increasing disorder
B.
Exothermic and decreasing disorder
C.
Endothermic and increasing disorder
D.
Endothermic and decreasing disorder
2005 NEET MCQ
AIPMT 2005
A reaction occurs spontaneously if
A.
T$\Delta $S < $\Delta $H and both $\Delta $H and $\Delta $S are +ve
B.
T$\Delta $S > $\Delta $H and $\Delta $H is +ve and $\Delta $S are $-$ve
C.
T$\Delta $S > $\Delta $H and both $\Delta $H and $\Delta $S are +ve
D.
T$\Delta $S = $\Delta $H and both $\Delta $H and $\Delta $S are +ve
2005 NEET MCQ
AIPMT 2005
The absolute enthalpy of neutralisation of the reaction :

Mg(O)(s) + 2HCl(aq) $ \to $ MgCl2(aq) + H2O(l) will be
A.
$-$57.33 kJ mol$-$1
B.
greater than $-$ 57.33 kJ mol$-$1
C.
less than $-$ 57.33 kJ mol$-$1
D.
57.33 kJ mol$-$1
2004 NEET MCQ
AIPMT 2004
Standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are $-$ 382.64 kJ mol$-$1 and $-$ 145.6 kJ mol$-$1, respectively. Standard Gibb's energy change for the same reaction at 298 K is
A.
$-$ 221.1 kJ mol$-$1
B.
$-$339.3 kJ mol$-$1
C.
$-$ 439.3 kJ mol$-$1
D.
$-$ 523.2 kJ mol$-$1
2004 NEET MCQ
AIPMT 2004
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 L atm = 101.32 J)
A.
$-$ 6 J
B.
$-$ 608 J
C.
+ 304 J
D.
$-$ 304 J
2004 NEET MCQ
AIPMT 2004
If the bond energies of H $-$ H, Br $-$ Br, and H $-$ Br are 433, 192 and 364 kJ mol$-$1 respectively, the $\Delta $Ho for the reaction

H2(g) + Br2(g) $ \to $ 2HBr(g) is
A.
$-$ 261 kJ
B.
+103 kJ
C.
+261 kJ
D.
$-$103 kJ
2004 NEET MCQ
AIPMT 2004
Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is
A.
$\Delta {S_{system}} + \Delta {S_{surroundings}} > 0$
B.
$\Delta {S_{system}} - \Delta {S_{surroundings}} > 0$
C.
$\Delta {S_{system}} > 0\,\,\,$only
D.
$\Delta {S_{surroundings}} > 0$ only
2003 NEET MCQ
AIPMT 2003
Formation of solution from two components can be considered as
(i) Pure solvent $ \to $ separated solvent molecules, $\Delta $H1
(ii) Pure solute $ \to $ separated solute molecules, $\Delta $H2
(iii) Separated solvent and solute molecules $ \to $ solution, $\Delta $H3
Solution so formed will be ideal if
A.
$\Delta $Hsoln = $\Delta $H1 + $\Delta $H2 + $\Delta $H3
B.
$\Delta $Hsoln = $\Delta $H1 + $\Delta $H2 $-$ $\Delta $H3
C.
$\Delta $Hsoln = $\Delta $H1 $-$ $\Delta $H2 $-$ $\Delta $H3
D.
$\Delta $Hsoln = $\Delta $H3 $-$ $\Delta $H1 $-$ $\Delta $H2
2003 NEET MCQ
AIPMT 2003
The molar heat capacity of water at constant pressure, C, is 75 J K$-$1 mol$-$1. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is
A.
1.2 K
B.
2.4 K
C.
4.8 K
D.
6.6 K
2003 NEET MCQ
AIPMT 2003
What is the entropy change (in J K$-$1 mol$-$1) when one mole of ice is converted into water at 0oC? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol$-$1 at 0oC).
A.
20.13
B.
2.013
C.
2.198
D.
21.98
2003 NEET MCQ
AIPMT 2003
For the reaction,
C3H8(g) + 5O2(g) $ \to $ 3CO2(g) + 4H2O(l)
at constant temperature, $\Delta $H $-$ $\Delta $E is
A.
+ RT
B.
$-$3RT
C.
+ 3RT
D.
$-$ RT
2003 NEET MCQ
AIPMT 2003
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm$-$3, respectively. If the standard free energy difference $\left( {\Delta {G^o}} \right)$ is equal to 1895 J mol$-$1, the pressure at which graphite will be transformed into diamond at 298 K is
A.
11.14 $ \times $ 108 Pa
B.
11.14 $ \times $ 107 Pa
C.
11.14 $ \times $ 106 Pa
D.
11.14 $ \times $ 105 Pa
2003 NEET MCQ
AIPMT 2003
For which one of the following equations is $\Delta $Horeact equal to $\Delta $Hof for the product ?
A.
Xe(g) + 2F2(g) $ \to $ XeF4(g)
B.
2CO(g) + O2(g) $ \to $ 2CO2(g)
C.
N2(g) + O3(g) $ \to $ N2O3(g)
D.
CH4(g) + 2Cl2(g) $ \to $ CH2Cl2(l) + 2HCl(g)
2002 NEET MCQ
AIPMT 2002
2 mole of ideal gas at 27oC temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change. (R = 2 cal/mol K)
A.
92.1
B.
0
C.
4
D.
9.2
2002 NEET MCQ
AIPMT 2002
Which reaction is not feasible?
A.
2KI + Br2 $ \to $ 2KBr + I2
B.
2KBr + I2 $ \to $ 2KI + Br2
C.
2KBr + Cl2 $ \to $ 2KCl + Br2
D.
2H2O + 2F2 $ \to $ 4HF + O2
2002 NEET MCQ
AIPMT 2002
Unit of entropy is
A.
J K$-$1 mol$-$1
B.
J mol$-$1
C.
J$-$1 K$-$1 mol$-$1
D.
J K mol$-$1
2002 NEET MCQ
AIPMT 2002
In a closed insulated container a liquid is stirred with a paddle to increase the temperature which of the following is true ?
A.
$\Delta $E = W $ \ne $ 0, q = 0
B.
$\Delta $E = w = q $ \ne $ 0
C.
$\Delta $E = 0, W = q $ \ne $ 0
D.
W = 0, $\Delta $E = q $ \ne $ 0.
2002 NEET MCQ
AIPMT 2002
Heat of combustion $\Delta $Ho for C(s), H2(g) and CH4(g) are $-$ 94, $-$ 68 and $-$213 kcal/mol, then $\Delta $Ho for C(s) + 2H2(g) $ \to $ CH4(g) is
A.
$-$17 kcal
B.
$-$111 kcal
C.
$-$170 kcal
D.
$-$85 kcal
2001 NEET MCQ
AIPMT 2001
Change in enthalpy for reaction,

2H2O2(l) $ \to $ 2H2O(l) + O2(g)

if heat of formation of H2O2(l) and H2O(l) are $-$188 and - 286 kJ/mol respectively, is
A.
$-$ 196 kJ/mol
B.
+ 196 kJ/mol
C.
+948 kJ/mol
D.
$-$ 948 kJ/mol
2001 NEET MCQ
AIPMT 2001
When 1 mol of gas is heated at constant volume temperature is raised from 298 to 308 K. Heat supplied to the gas is 500 J. Then which statement is correct ?
A.
q = w = 500 J, $\Delta $E = 0
B.
q = $\Delta $E = 500 J, w = 0
C.
q = w = 500 J, $\Delta $E = 0
D.
$\Delta $E = 0, q = w = $-$ 500 J
2001 NEET MCQ
AIPMT 2001
PbO2  $ \to $ PbO; $\Delta $G298 < 0
SnO2 $ \to $ SnO;  $\Delta $G298 > 0

Most probable oxidation state of Pb and Sn will be
A.
Pb4+, Sn4+
B.
Pb4+, Sn2+
C.
Pb2+, Sn2+
D.
Pb2+, Sn4+
2001 NEET MCQ
AIPMT 2001
Enthalpy of CH4 + ${1 \over 2}$ O2 $ \to $ CH3OH is negative. If enthalpy of combustion of CH4 and CH3OH are x and y respectively. Then which relation is correct?
A.
x > y
B.
x < y
C.
x = y
D.
x3 y
2000 NEET MCQ
AIPMT 2000
The entropy change in the fusion of one mole of a solid melting at 27oC (latent heat of fusion is 2930 J mol–1) is :
A.
9.77 J/mol-K
B.
10.77 J/mol-K
C.
9.07 J/mol-K
D.
0.977 J/mol-K
2000 NEET MCQ
AIPMT 2000
2Zn + O2 $ \to $ 2ZnO;  $\Delta $Go = $-$ 616 J
2Zn + S2 $ \to $ 2ZnS;  $\Delta $Go = $-$ 293 J
S2 + 2O2 $ \to $ 2SO2;   $\Delta $Go = $-$408 J
$\Delta $Go for the following reaction
2ZnS + 3O2 $ \to $  2ZnO + 2SO2 is
A.
$-$ 731 J
B.
$-$ 1317 J
C.
$-$ 501 J
D.
+ 731 J
2000 NEET MCQ
AIPMT 2000
For the reaction,
C2H5OH(l) + 3O2(g) $ \to $ 2CO2(g) + 3H2O(l)
which one is true
A.
$\Delta $H = $\Delta $E $-$RT
B.
$\Delta $H = $\Delta $E + RT
C.
$\Delta $H = $\Delta $E + 2RT
D.
$\Delta $H = $\Delta $E $-$ 2RT