23267.Which statement is incorrect?
All reversible cycles have same efficiency.
Reversible cycle has more efficiency than an irreversible one.
Carnot cycle is a reversible one.
Carnot cycle has the maximum efficiency in all cycles.
23268.A refrigerator works between 4°C and 30°C. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is [Take 1 cal = 4.2 joules)
236.5 W
2365 W
2.365 W
23.65 W
23269.A Carnot engine, whose efficiency is 40%, takes in heat from a source maintained at a temperature of 500K. It is desired to have an engine of efficiency 60%, then the intake temperature for the same exhaust (sink) temperature must be :
efficiency of Carnot engine cannot be made larger than 50%
1200 K
750 K
600 K
23270.An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?
Isothermal
Adiabatic
Isobaric
Isochoric
23271.Figure below shows two paths that may be taken by a gas to go from a state A to a state C. In process AB, 400 J of heat is added to the system and in process BC, 100 J of heat is added to the system. The heat absorbed by the system in the process AC will be
380 J
500 J
460 J
300 J
23272.A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then
Compressing the gas isothermally or adiabatically will require the same amount of work
Which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas
Compressing the gas isothermally will require more work to be done
Compressing the gas through adiabatic process will require more work to be done
23273.One mole of an ideal diatomic gas undergoes a transition from A to B along a path AB as shown in the figure,
The change in internal energy of the gas during the transition is
The change in internal energy of the gas during the transition is
20 kJ
–20 kJ
20 J
–12 kJ
23274.The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is –20°C, the temperature of the surroundings to which it rejects heat is
21°C
31°C
41°C
11°C
23275.A piece of ice falls from a height h so that it melts completely. Only one–quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is
[Latent heat of ice is 3.4 × 105 J/kg and g = 10 N/kg]
[Latent heat of ice is 3.4 × 105 J/kg and g = 10 N/kg]
136 km
68 km
34 km
544 km
23276.An ideal gas heat engine operates in a Carnot cycle between 227ºC and 127ºC. It absorbs 6 kcal at the higher temperature. The amount of heat (in kcal) converted into work is equal to
4.8
3.5
1.6
1.2