The unit of entropy is:

1. JK–1 mol–1 2. J mol–1
3. J–1K–1 mol–1 4. JK mol–1

Subtopic:  Spontaneity & Entropy |
 88%
Level 1: 80%+
AIPMT - 2002
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In a closed insulated container a liquid is stirred with a paddle to increase the temperature. The correct option regarding this among the following is:

1. ∆E = W ≠ 0, q = 0

2. ∆E = W = q ≠ 0

3. ∆E = 0, W = q ≠ 0

4. W = 0 , ∆E = q ≠ 0

Subtopic:  First Law of Thermodynamics |
 79%
Level 2: 60%+
AIPMT - 2002
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2 mole of an 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
Subtopic:  Spontaneity & Entropy |
 64%
Level 2: 60%+
AIPMT - 2002
Hints

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Given that the standard heats of combustion (ΔH°) of C(s), H₂(g), and CH₄(g) are −94 kcal/mol, −68 kcal/mol, and −213 kcal/mol, respectively.
What is the standard enthalpy change (ΔH°) for the reaction:

C(s) + 2H₂(g) → CH₄(g)?

1. – 17 Kcal 2. – 111 Kcal
3. – 170 Kcal 4. – 85 Kcal
Subtopic:  Thermochemistry |
 86%
Level 1: 80%+
AIPMT - 2002
Hints

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 |
 78%
Level 2: 60%+
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 =0, w = 500 J, ∆U = 0
4.  ∆U = 0, q = w = – 500 J

Subtopic:  First Law of Thermodynamics |
 88%
Level 1: 80%+
AIPMT - 2001
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The enthalpy of \(CH_4 + \dfrac{1}{2 }O_2 \rightarrow\ CH_3OH\) is negative. If enthalpy of combustion of methane and \(CH_3OH\) are x and y, respectively, then which of the following relations is correct?

1. x > y 2. x < y
3. x = y 4. x ≥ y
Subtopic:  Enthalpy & Internal energy |
 63%
Level 2: 60%+
AIPMT - 2001
Hints

The difference between enthalpy (∆H) and internal energy (∆E) for the given below reaction,
under constant temperature, is:
\(C_{3} H_{8} \left(\right. g \left.\right) + 5 O_{2} \left(\right. g \left.\right) \rightarrow 3 CO_{2} \left(\right. g \left.\right) + 4 H_{2} O \left(\right. l \left.\right)\)

1. + RT 2. – 3RT
3. + 3RT 4. – RT
Subtopic:  Enthalpy & Internal energy |
 85%
Level 1: 80%+
AIPMT - 2003
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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 (∆Gº) is equal to 1895 J mol–1, the pressure at which graphite will be transformed into diamond at 298 K is:

1. 11.08×108 Pa

2. 9.92×107 Pa

3. 9.92×106 Pa

4. 11.08×105 Pa

Subtopic:  Gibbs Energy Change |
Level 3: 35%-60%
AIPMT - 2003
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What is the entropy change (in JK–1 mol–1) when one mole of ice is converted into water at 0 ºC?
(The enthalpy change for the conversion of ice to liquid water is 6.0 KJ mol–1 at 0 ºC)

1. 20.13 2. 2.013
3. 2.198 4. 21.98
Subtopic:  Spontaneity & Entropy |
 78%
Level 2: 60%+
AIPMT - 2003
Hints