The coefficient of performance of an ideal refrigerator is 3 which extracts heat from the sink at the rate of 399 J per cycle. The amount of heat it gives to the room per cycle will be:

1 532 J

2 250 J

3 300 J

4 496 J

Subtopic:  Heat Engine & Refrigerator (OLD NCERT) |
 75%
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If a gas undergoes the change in its thermodynamic state from A to B via two different paths, as shown in the given pressure (P) versus volume (V) graph, then:

1. the temperature of the gas decreases in path 1 from A to B.
2. the heat absorbed by the gas in path 1 is greater than in path 2.
3. the heat absorbed by the gas in path 2 is greater than in path 1.
4. the change in internal energy in path 1 is greater than in path 2.

Subtopic:  First Law of Thermodynamics |
 76%
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The PV diagram of an ideal gas is shown in the figure. The work done by the gas in the process 1234 is given by:

          

1. \(\frac{9}{2}P_0V_0\) 2. \(\frac{15}{2}P_0V_0\)
3. \(\frac{13}{2}P_0V_0\) 4. \(\frac{3}{2}P_0V_0\)
Subtopic:  Work Done by a Gas |
 52%
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A pressure (P) versus volume (V) graph is obtained for an ideal gas from state A to State B (as shown in the figure below). Which of the following is the correct statement?
      

1. The temperature of gas increases continuously.
2. The temperature of gas decreases continuously.
3. The temperature first increases, then decreases.
4. The temperature first decreases, then increases

Subtopic:  Types of Processes |
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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
Subtopic:  Carnot Engine |
 64%
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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.
Subtopic:  Types of Processes |
 84%
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A gas performs the minimum work when it expands:

1. Isochorically 2. Isobarically
3. Adiabatically 4. Isothermally
Subtopic:  Types of Processes |
 71%
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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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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
Subtopic:  First Law of Thermodynamics |
 78%
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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 W1 and W2 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. \(W_{1}\) =  \(-W_{2}\)
Subtopic:  Work Done by a Gas |
 71%
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