We consider a thermodynamic system. If ΔU represents the increase in its internal energy and W the work done by the system, which of the following statements is true ?

1. ΔU = –W in an adiabatic process

2. ΔU = W in an isothermal process

3. ΔU = –W in an isothermal process

4. ΔU = W in an adiabatic process

Subtopic:  Types of Processes |
 85%
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The volume of a gas is reduced adiabatically to 14 of its volume at 27°C, if the value of γ = 1.4, then the new temperature will be - 

(1) 350 × 40.4 K

(2) 300 × 40.4 K

(3) 150 × 40.4 K

(4) None of these

Subtopic:  Types of Processes |
 92%
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For an adiabatic expansion of a perfect gas, the value of ΔPP is equal to 

(1) γΔVV

(2) ΔVV

(3) γΔVV

(4) γ2ΔVV

Subtopic:  Types of Processes |
 91%
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One mole of a perfect gas in a cylinder fitted with a piston has a pressure P, volume V and temperature 273 K. If the temperature is increased by 1 K keeping pressure constant, the increase in volume is

(1) 2V273

(2) V91

(3) V273

(4) V

Subtopic:  Types of Processes |
 76%
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A unit mass of a liquid with volume V1 is completely changed into a gas of volume V2 at a constant external pressure P and temperature T. If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is: 
1.  Zero
2. P(V2V1)
3. LP(V2V1)
4.  L

Subtopic:  First Law of Thermodynamics |
 63%
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If 300 ml of a gas at 27°C is cooled to 7°C at constant pressure, then its final volume will be -

(1) 540 ml

(2) 350 ml

(3) 280 ml

(4) 135 ml

Subtopic:  Types of Processes |
 90%
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If the door of a refrigerator is kept open, then which of the following is true ?

1. Room is cooled

2. Room is heated

3. Room is either cooled or heated

4. Room is neither cooled nor heated

Subtopic:  Heat Engine & Refrigerator (OLD NCERT) |
 77%
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A Carnot's engine used first an ideal monoatomic gas then an ideal diatomic gas. If the source and sink temperature are 411°C and 69°C respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the PV diagram is -

(1) 100 J

(2) 300 J

(3) 500 J

(4) 700 J

Subtopic:  Heat Engine & Refrigerator (OLD NCERT) |
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The temperature of reservoir of Carnot's engine operating with an efficiency of 70% is 1000K. The temperature of its sink is -

(1) 300 K

(2) 400 K

(3) 500 K

(4) 700 K

Subtopic:  Heat Engine & Refrigerator (OLD NCERT) |
 88%
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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

Subtopic:  Heat Engine & Refrigerator (OLD NCERT) |
 76%
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