Identify the correct statement regarding entropy:

1. At absolute zero of temperature, the entropy of all crystalline substances is taken to be zero
2. At absolute zero of temperature, the entropy of a perfectly crystalline substance is +ve
3. At absolute zero of temperature, the entropy of a perfectly crystalline substance is taken to be zero
4. At 0 °C , the entropy of a perfectly crystalline substance is taken to be zero
Subtopic:  2nd & 3rd Law of Thermodynamics |
 63%
From NCERT
AIPMT - 1998
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One mole of an ideal gas at 300 K is expanded isothermally from an initial volume of 1 litre to 10 litres. The ∆E for this process is:
(R = 2 cal. mol-1K-1)
1. 1381.1 cal.
2. Zero
3. 163.7 cal.
4. 9 lit. atm

Subtopic:  First Law of Thermodynamics |
 81%
From NCERT
AIPMT - 1998
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What is true for a cyclic process:

a. W = 0
b. ∆E = 0
c. ∆H = 0
d. ∆E ≠ 0


1.  a, b
2.  b, c
3.  c, d
4.  a, d

Subtopic:  Enthalpy & Internal energy |
 69%
From NCERT
AIPMT - 1999
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If a system is expanded under adiabatic process, then:

1.  Temperature increases
2.  ∆E decreases
3.  ∆E increases
4.  None of the above

Subtopic:  Enthalpy & Internal energy |
 60%
From NCERT
AIPMT - 1999
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Which of the following is true for a reaction in which all the reactants & products are liquids:
1.  ∆H = ∆E
2.  ∆H = ∆W
3.  ∆H > ∆E
4.  None of the above

Subtopic:  Enthalpy & Internal energy |
 82%
From NCERT
AIPMT - 1999
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2Zn+O22ZnO    G°=-616 J
2Zn+S22ZnS     G°=-293 J
S2+2O22SO2     G°=-408J

G° for the following reaction is:

2ZnS+3O22ZnO+2SO2

1. -731 J 2. -1317 J
3. -501 J 4. +731 J
Subtopic:  Gibbs Energy Change | Thermochemistry |
 78%
From NCERT
AIPMT - 2000
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At 27ºC latent heat of fusion of a compound is 2930 J/mol. Entropy change is:

1. 9.77 J/mol K

2. 10.77 J/mol K

3. 9.07 J/mol K

4. 0.977 J/mol K

Subtopic:  Spontaneity & Entropy |
 83%
From NCERT
AIPMT - 2000
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For the reaction
C2H5OH(l) + 3O2(g) →2CO2(g) + 3H2O(l) which one is true:

1. ∆H = ∆E – RT 2. ∆H = ∆E + RT
3. ∆H = ∆E + 2RT 4. ∆H = ∆E – 2RT
Subtopic:  Enthalpy & Internal energy |
 83%
From NCERT
AIPMT - 2000
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For the given reaction 

2H2O2(l)  2H2O(l) + O2(g), the heat of formations of H2O2(l)  and H2O (l) are -188 kJ/mol & -286 KJ/mol respectively. The change in the enthalpy of the reaction will be:

1.  – 196 kJ/mol

2.  + 196 kJ/mol

3.  + 948 kJ/mol

4.  – 948 kJ/mol

Subtopic:  Enthalpy & Internal energy |
 74%
From NCERT
AIPMT - 2001
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When 1 mol gas is heated at constant volume, the temperature is raised from 298 to 308 K. Heat supplied to the gas is 500 J. The correct statement among the following is:
1.  q = w = 500 J, ∆U = 0
2.  q = ∆U = 500 J, w = 0
3.  q = w = 500 J, ∆U = 0
4.  ∆U = 0, q = w = – 500 J

Subtopic:  First Law of Thermodynamics |
 86%
From NCERT
AIPMT - 2001
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