5.6 litre of helium gas at STP is adiabatically compressed to 0.7 litre. Taking the initial temperature to be T1, the work done in the process is
The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is
1/3
1/2
2/3
1/4
110 J of heat is added to a gaseous system, whose internal energy is 40 J, then the amount of external work done is
150 J
70 J
110 J
40 J
Initial pressure and volume of a gas are P and V respectively. First the gas is expanded isothermally to 4V and then its volume is made V by adiabatic process. Its final pressure (γ = 1.5) is
8 P
4 P
P
2 P
In thermodynamic processes 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 adiabatic process pVγ = constant
An ideal gas heat engine is operating between 227oC and 127oC. It absorbs 104 J of heat at the higher temperature. The amount of heat converted into work is
2000 J
4000 J
8000 J
5600 J
A diatomic ideal gas is used in a Carnot engine as the working substance. If during the adiabatic expansion part of the cycle the volume of the gas increased from V to 32 V, the efficiency of the engine is
0.25
0.5
0.75
0.99
The efficiency of Carnot engine is 50% and temperature of sink is 500 K. If the temperature of source is kept constant and its efficiency is to be raised to 60%, then the required temperature of the sink will be
600 K
500 K
400 K
100 K
An ideal mono atomic gas is taken round the cycle ABCDA as shown in the P-V diagram.
PV
2 PV
PV / 2
zero
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?
ΔU = - W in an adiabatic process
ΔU = W in an isothermal process
ΔU = - W in an isothermal process
ΔU = W in an adiabatic process
