The latent heat of vaporisation of water is \(2240~\text{J/gm}\). If the work done in the process of expansion of \(1~\text{g}\) is \(168~\text{J}\), then the increase in internal energy is:
1. \(2408~\text{J}\)
2. \(2240~\text{J}\)
3. \(2072~\text{J}\)
4. \(1904~\text{J}\)

Subtopic:  First Law of Thermodynamics |
 82%
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An ideal heat engine working between temperatures T1 and T2 has an efficiency η. The new efficiency if both the source and sink temperatures are doubled will be:
1. η2
2. η
3. 2η
4. 3η

Subtopic:  Carnot Engine |
 88%
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A monoatomic ideal gas, initially at temperature \(T_1\), is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature \(T_2\) by releasing the piston suddenly. If \(L_1\) and \(L_2\) are the lengths of the gas column before and after expansion, respectively, then \(\frac{T_1}{T_2}\) is given by:
1. \(\left(\frac{L_1}{L_2}\right)^{\frac{2}{3}}\)
2. \(\frac{L_1}{L_2}\)
3. \(\frac{L_2}{L_1}\)
4. \(\left(\frac{L_2}{L_1}\right)^{\frac{2}{3}}\)

Subtopic:  Types of Processes |
 70%
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The initial pressure and volume of a gas are \(P\) and \(V\), respectively. First, it is expanded isothermally to volume \(4V\) and then compressed adiabatically to volume \(V\). The final pressure of the gas will be: [Given: \(\gamma = 1.5\)]

1. \(P\) 2. \(2P\)
3. \(4P\) 4. \(8P\)
Subtopic:  Types of Processes |
 74%
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If n moles of an ideal gas is heated at a constant pressure from 50°C to 100°C, the increase in the internal energy of the gas will be: \(\left(\frac{C_{p}}{C_{v}} = \gamma\   and\   R = gas\   constant\right)\)

1. \(\frac{50   nR}{\gamma - 1}\) 2. \(\frac{100   nR}{\gamma - 1}\)
3. \(\frac{50   nγR}{\gamma - 1}\) 4. \(\frac{25   nγR}{\gamma - 1}\)
Subtopic:  Molar Specific Heat |
 81%
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The figure below shows two paths that may be taken by a gas to go from state A to state C. In process AB, \(400~\text{J}\) of heat is added to the system and in process BC, \(100~\text{J}\) of heat is added to the system. The heat absorbed by the system in the process AC will be:

        

1. \(380~\text{J}\) 2. \(500~\text{J}\)
3. \(460~\text{J}\) 4. \(300~\text{J}\)
Subtopic:  First Law of Thermodynamics |
 65%
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The first law of thermodynamics is based on:

1. the concept of temperature.
2. the concept of conservation of energy.
3. the concept of working of heat engine.
4. the concept of entropy.

Subtopic:  First Law of Thermodynamics |
 92%
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The efficiency of an ideal heat engine is less than 100% because of:

1.  the presence of friction.
2.  the leakage of heat energy.
3.  unavailability of the sink at zero kelvin.
4.  All of these

Subtopic:  Carnot Engine |
 83%
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Work done during the given cycle is:
                               
1. 4P0V0

2. 2P0V0

3. 12P0V0

4. P0V0

Subtopic:  Work Done by a Gas |
 78%
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An ideal gas goes from A to B via two processes, l and ll, as shown. If U1 and U2 are the changes in internal energies in processes I and II, respectively, then (\(P:\) pressure, \(V:\) volume)

 

1. ∆U1 > ∆U2 2. ∆U1 < ∆U2
3. ∆U1 = ∆U2 4. ∆U1 ≤ ∆U2
Subtopic:  Molar Specific Heat |
 87%
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