Q. No.When the sink temperature is kept at 400 K, the efficiency of a Carnot engine is 50%. While keeping the source temperature constant, by how much should we reduce the sink temperature to increase the efficiency to 60%?
1.
80 K
2.
70 K
3.
320 K
4.
240 K
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Which of the following graph shows the variation of pressure P with volume V for an ideal gas at a constant temperature?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
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A gas performs the minimum work when it expands:
| 1. | Isochorically | 2. | Isobarically |
| 3. | Adiabatically | 4. | Isothermally |
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An ideal gas goes from A to B via two processes, l and ll, as shown. If and 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 |
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An ideal monoatomic gas \(\left(\gamma = \frac{5}{3}\right )\) absorbs 50 cal in an isochoric process. The increase in internal energy of the gas is:
| 1. | 20 cal | 2. | Zero |
| 3. | 50 cal | 4. | 30 cal |
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The pressure-temperature (P-T) graph for two processes, A and B, in a system is shown in the figure. If and are work done by the gas in process A and B respectively, then:
| 1. | \(W_{1}\) = \(W_{2}\) | 2. | \(W_{1}\) < \(W_{2}\) |
| 3. | \(W_{1}\) > \(W_{2}\) | 4. | \(W_{1}\) = \(-W_{2}\) |
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The variation of molar heat capacity at constant volume with temperature T for a monatomic gas is:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
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When a system is moved from state a to state b along the path acb, it is discovered that the system absorbs 200 J of heat and performs 80 J of work. Along the path adb, heat absorbed Q = 144 J. The work done along the path adb is:
| 1. | 6 J | 2. | 12 J |
| 3. | 18 J | 4. | 24 J |
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If a refrigerator extracts heat 'a' from the cold reservoir and 'b' is the heat released from the hot reservoir, then the work done on the refrigerant (system) is:
1. a + b
2.
3. a
4.
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Heat is supplied to a diatomic gas in an isochoric process. The ratio is: (symbols have usual meanings)
1. 5 : 3
2. 5: 2
3. 1: 1
4. 5: 7
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