A Carnot engine whose sink is at 300 K has an efficiency of 40%.

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91.

A mass of diatomic gas left parenthesis straight gamma space equals space 1.4 right parenthesis at a pressure of 2 atm is compressed adiabatically so that its temperature rise from 27oC to 927o C. The pressure of the gas is final state is 

  • 28 atm

  • 68.7 atm

  • 256 atm

  • 256 atm

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92.

If ΔU and ΔW represent the increase in internal energy and work done by the system respectively in the thermodynamical process, which of the following is true?

  • ΔU = - ΔW, in a adiabatic process

  • ΔU = ΔW, in an isothermal process

  • ΔU = ΔW, in an adiabatic process

  • ΔU = ΔW, in an adiabatic process

372 Views

93.

A monatomic gas at pressure p1 and V1 is compressed adiabatically to 1/8 th its original volume. What is the final pressure of the gas?

  • 64 p1

  • p1

  • 16 p1

  • 16 p1

1302 Views

94.

The internal energy change in a system that has absorbed 2 Kcal of heat and done 500 J of work is 

  • 8900 J

  • 6400 J

  • 5400 J

  • 5400 J

1261 Views

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95.

In a thermodynamic process which of the following statements is not true?

  • In an adiabatic process, the system is insulated from the surroundings

  • In an isochoric process pressure remains constant

  • In an isothermal process, the temperature remains constant

  • In an isothermal process, the temperature remains constant

415 Views

96.

If Q, E andW denote respectively the heat added, change in internal energy and the work done in a closed cycle process, then

  • W =0

  • Q = W = 0

  • E=0

  • E=0

335 Views

97.

In producing chlorine through electrolysis 100 W power at 125 V is being consumed. How much chlorine per min is liberated? ECE of chlorine is 0.367 x 10-6 kg/C

  • 17.6 mg

  • 21.3 mg

  • 24.3 mg

  • 24.3 mg

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98.

A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of source be increased so as to increase its efficiency by 50% of original efficiency?

  • 275 K

  • 175 K

  • 250 K

  • 250 K


C.

250 K

The efficiency of Carnot engine is defined as the ratio of work done to the heat supplied i.e., 
                          
Here,  is the temperature of source and T2 is the temperature of sink
    As given,             
and                
So,        
       
Let temperature of the source be increased by x K, then efficiency becomes



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99.

The molar specific heat at constant pressure of an ideal gas is (7/2)R. The ratio of specific heat at constant pressure to that at constant volume is

  • 7/5

  • 8/7

  • 5/7

  • 5/7

943 Views

100.

Two rods A and B of different materials are welded together as shown in the figure. Their thermal conductivities are K1 and K2. The thermal conductivity of the composite rod will be

  • fraction numerator straight K subscript 1 space plus space straight K subscript 2 over denominator 2 end fraction
  • fraction numerator 3 space left parenthesis straight K subscript 1 space plus space straight K subscript 2 right parenthesis over denominator 2 end fraction
  • k1 + k2

  • k1 + k2

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