Efficiency of a Carnot engine is 50% when temperature of outlet is 500 K. In order to increase efficiency up to 60% keeping temperature of intake the same what is temperature of outlet ?

(1) 200 K

(2) 400 K

(3) 600 K

(4) 800 K

 76%
Level 2: 60%+
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An ideal heat engine (Carnot engine) works between temperatures \(T_1\) and \(T_2\) has an efficiency \(\eta.\) The new efficiency if both the source and sink temperatures are doubled will be:
1. \(\frac{\eta}{2}\)
2. \(\eta\)
3. \(2\eta\)
4. \(3\eta\)
Subtopic:  Carnot Engine |
 89%
Level 1: 80%+
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An engine is supposed to operate between two reservoirs at temperature 727°C and 227°C. The maximum possible efficiency of such an engine is -

(1) 1/2

(2) 1/4

(3) 3/4

(4) 1

 86%
Level 1: 80%+
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An ideal gas heat engine operates in Carnot cycle between 227°C and 127°C. It absorbs 6 × 104 cal of heat at higher temperature. Amount of heat converted to work is -

(1) 2.4 × 104 cal

(2) 6 × 104 cal

(3) 1.2 × 104 cal

(4) 4.8 × 104 cal

 81%
Level 1: 80%+
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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 |
 71%
Level 2: 60%+
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An ideal gas expands isothermally from a volume V1 to V2 and then compressed to original volume V1 adiabatically. Initial pressure is P1 and final pressure is P3. The total work done is W. Then -

(1) P3>P1,  W>0

(2) P3<P1,  W<0

(3) P3>P1,  W<0

(4) P3=P1,  W=0

Subtopic:  Work Done by a Gas |
Level 3: 35%-60%
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An insulator container contains \(4\) moles of an ideal diatomic gas at a temperature \(T.\) If heat \(Q\) is supplied to this gas, due to which \(2\) moles of the gas are dissociated into atoms, but the temperature of the gas remains constant, then:
1. \(Q=2RT\)
2. \(Q=RT\)
3. \(Q=3RT\)
4. \(Q=4RT\)

Subtopic:  First Law of Thermodynamics |
Level 3: 35%-60%
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The volume of air (diatomic) increases by \(5\%\) in its adiabatical expansion. The percentage decrease in its pressure will be:

1. \(5\%\) 2. \(6\%\)
3. \(7\%\) 4. \(8\%\)
Subtopic:  Types of Processes |
 53%
Level 3: 35%-60%
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The temperature of a hypothetical gas increases to 2 times when compressed adiabatically to half the volume. Its equation can be written as

(1) PV3/2 = constant

(2) PV5/2 = constant

(3) PV7/3 = constant

(4) PV4/3 = constant

Subtopic:  Types of Processes |
 77%
Level 2: 60%+
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Two Carnot engines A and B are operated in succession. The first one, A receives heat from a source at \(T_1=800\) K and rejects to sink at \(T_2\) K. The second engine, B, receives heat rejected by the first engine and rejects to another sink at \(T_3=300\) K. If the work outputs of the two engines are equal, then the value of \(T_2\) will be:

1. 100 K 2. 300 K
3. 550 K 4. 700 K
Subtopic:  Carnot Engine |
 73%
Level 2: 60%+
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