An engine has an efficiency of 16. When the temperature of the sink is reduced by 620C, its efficiency is doubled. the temperature of the source is:

1. 124oC

2. 37oC

3. 62oC

4. 99oC

Subtopic:  Heat Engine & Refrigerator (OLD NCERT) |
 56%
From NCERT
AIPMT - 2007
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A Carnot engine whose sink is at \(300~\mathrm{K}\) has an efficiency of \(40\)%. By how much should the temperature of the source be increased to increase its efficiency by \(50\)% of its original efficiency?

1. \(275~\mathrm{K}\) 2. \(325~\mathrm{K}\)
3. \(250~\mathrm{K}\) 4. \(380~\mathrm{K}\)
Subtopic:  Carnot Engine |
 64%
From NCERT
AIPMT - 2006
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The molar specific heat at a constant pressure of an ideal gas is \(\frac{7}{2}R.\) The ratio of specific heat at constant pressure to that at constant volume is:
1. \(\frac{7}{5}\)
2. \(\frac{8}{7}\)
3. \(\frac{5}{7}\)
4. \(\frac{9}{7}\)

Subtopic:  Molar Specific Heat |
 76%
From NCERT
AIPMT - 2006
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In which of the following processes, the heat is neither absorbed nor released by a system?
1. isochoric
2. isothermal
3. adiabatic
4. isobaric

Subtopic:  Types of Processes |
 86%
From NCERT
NEET - 2019
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If for a given substance melting point is TB and freezing point is TA, then correct variation shown by graph between entropy change and temperature is

1. 

2.

3.

4. 

Subtopic:  Second Law of Thermodynamics |
 54%
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The internal energy change in a system that has absorbed \(2\) kcal of heat and done \(500\) J of work is:
1. \(8900\) J
2. \(6400\) J
3. \(5400\) J
4. \(7900\) J

Subtopic:  First Law of Thermodynamics |
 77%
From NCERT
AIPMT - 2009
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During an isothermal expansion, a confined ideal gas does -150 J of work against its surrounding. This implies that:

1. 300 J of heat has been added to the gas.
2. no heat is transferred because the process is isothermal.
3. 150 J of heat has been added to the gas.
4. 150 J of heat has been removed from the gas.

Subtopic:  First Law of Thermodynamics |
 66%
From NCERT
AIPMT - 2011
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When \(1\) kg of ice at \(0^{\circ}\) C melts into the water at \(0^{\circ}\) C, the resulting change in its entropy, taking the latent heat of ice to be \(80\) cal/gm, is:
1. \(8\times 10^4\) cal/K
2. \(80\) cal/K
3. \(293\) cal/K
4. \(273\) cal/K

Subtopic:  Second Law of Thermodynamics |
 57%
From NCERT
AIPMT - 2011
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One mole of an ideal gas goes from an initial state \(A\) to the final state \(B\) with two processes. It first undergoes isothermal expansion from volume \(V\) to \(3V\) and then its volume is reduced from \(3V\) to \(V\) at constant pressure. The correct \((P-V)\) diagram representing the two processes is:

1. 2.
3. 4.

Subtopic:  Types of Processes |
 81%
From NCERT
AIPMT - 2012
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A thermodynamic system is taken through the cycle \(\mathrm{ABCD}\) as shown in the figure. Heat rejected by the gas during the cycle is: 
     

1. \(2 {PV}\)
2. \(4{PV}\)
3. \(\frac{1}{2}{PV}\)
4. \(PV\)

Subtopic:  Cyclic Process |
 73%
From NCERT
AIPMT - 2012
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