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

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
Hints

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
Hints

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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

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
Hints

The molar heat capacity of water at constant pressure, C, is 75 JK–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 the water is:

1. 1.2 K 2. 2.4 K
3. 4.8 K 4. 6.6 K
Subtopic:  First Law of Thermodynamics |
 78%
Level 2: 60%+
AIPMT - 2003
Hints

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Find the thermodynamic stability of NO(g) relative to NO₂(g) using the following data:

½N₂(g) + ½O₂(g) → NO(g)  ΔrH° = +90 kJ mol⁻¹

NO(g) + ½O₂(g) → NO₂(g)  ΔrH° = −74 kJ mol⁻¹
1. Less than NO₂(g)
2. More than NO₂(g)
3. Equal to NO₂(g)
4. Insufficient data

Subtopic:  Enthalpy & Internal energy |
 71%
Level 2: 60%+
Hints

What is the entropy change of the surroundings when 1.00 mol of liquid water (H₂O(l)) is formed under standard conditions?
[Given: ∆fHθ = –286 kJ mol–1 ]

1. 952. 5 J mol-1

2. 979.7 J mol-1

3. 949.7 J mol-1

4. 959.7 J mol-1

Subtopic:  Spontaneity & Entropy |
 54%
Level 3: 35%-60%
Hints
Links

For the graph given below, it can be concluded that work done during the process shown will be:

   

1. Zero 2. Negative
3. Positive 4. Cannot be determined
Subtopic:  First Law of Thermodynamics |
 69%
Level 2: 60%+
Hints

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Consider the following graph.

The work done, as per the graph above, is:

1. Positive 2. Negative
3. Zero 4. Cannot be determined
Subtopic:  First Law of Thermodynamics |
 73%
Level 2: 60%+
Hints