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 |
 81%
Level 1: 80%+
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 |
 85%
Level 1: 80%+
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 |
 86%
Level 1: 80%+
AIPMT - 2000
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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 |
 63%
Level 2: 60%+
AIPMT - 2002
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Heat of combustion ∆Hº for C(s), H2(g) and CH4(g) are – 94, – 68 and – 213 Kcal/mol. ∆Hº for C(s) + 2H2(g) → CH4 (g) is:

1. – 17 Kcal 2. – 111 Kcal
3. – 170 Kcal 4. – 85 Kcal
Subtopic:  Thermochemistry |
 85%
Level 1: 80%+
AIPMT - 2002
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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 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 |
 77%
Level 2: 60%+
AIPMT - 2003
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The formation of a solution from two components can be considered as:

(i) Pure solvent → separated solvent molecules, ∆H1
(ii) Pure solute → separated solute molecules, ∆H2
(iii) Separated solvent and solute molecules → solution, ∆H3


The solution so formed will be ideal if:

1. ∆HSoln = ∆H1 + ∆H2 + ∆H3

2. ∆HSoln = ∆H1 + ∆H2 – ∆H3

3. ∆HSoln = ∆H1 – ∆H2 – ∆H3

4. ∆HSoln = ∆H3 – ∆H1 – ∆H2

Subtopic:  Thermochemistry |
Level 3: 35%-60%
AIPMT - 2003
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