61.

In which of the processes, does the internal energy of the system remain constant ?

• Adiabatic 

• Isochoric

• Isobaric

• Isothermal

Which of the following is not a thermodynamic coordinate ?

• Gas constant (R)

• Pressure (p)

• Volume (V)

• Temperature (T)

The efficiency of Carnot's heat engine is 0.5 when the temperature of the source is T₁ and that of sink is T₂. The efficiency of another Carnot's heat engine is also 0.5. The temperatures of source and sink of the second engine are respectively

• 2T₁, 2T₂

• $2{\mathrm{T}}_1 ,\frac{{\mathrm{T}}_2}{2}$

• T₁ + 5, T₂ − 5

• T₁ + 10, T₂ − 10

One mole of an ideal gas is taken from A to B, from B to C and then C and A and then the variation of its volume with temperature for that change is as shown. Its pressure is p₀, volume is V₀, then the internal energy is

• at A and B are equal

• at A is more than at B

• at C is less than at B

• at B is more than at A

For which combination of working temperatures of source and sink, the efficiency of Carnot's heat engine is maximum ?

• 600 K, 400 K

• 400 K, 200 K

• 500 K, 300 K

• 300 K, 100 K

What is the source temperature ofthe Carnot engine required to get 70% efficiency ? Given, sink temperature = 27°C.

• 1000°C

• 90°C

• 270°C

• 727°C

A cycle tyre bursts suddenly. What is the type of this process ?

• Isothermal 

• Adiabatic

• Isochoric

• Isobaric

The efficiency of a Carnot engine which operates between the two temperatures T₁ = 500 K and T₂ = 300 K is

• 75 %

• 50 %

• 40 %

• 25 %

A Carnot engine working between 300 K and 400 K has 800 J of useful work. The amount of heat energy supplied to the engine from the source is

• 2400 J

• 3200 J

• 1200 J

• 3600 J

For which combination of working temperatures, the efficiency of engine is the least ?

• 100 K, 80 K

• 40 K, 20 K

• 80 K, 60 K

• 60 K, 40 K