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
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
An ideal gas is taken through the cycle A B C A as shown in the figure. If the net heat supplied to the gas in the cycle is 5 J, the work done by the gas in the process C A is
- 5 J
- 10 J
- 15 J
- 20 J
An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62oC, its efficiency is doubled. Temperature of the source is
124oC
37oC
62oC
99oC
"Heat cannot itself flow from a body at lower temperature to a body at higher temperature" is a statement or consequence of
second law of thermodynamics
conservation of momentum
conservation of mass
first law of thermodynamics
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
One mole of a mono atomic gas is heated at a constant pressure of 1 atmosphere from 0 K to 100 K. If the gas constant R = 8.32J/mol K, the change in internal energy of the gas is approximately
2.3 J
46 J
8.67 x 103 J
1.25 x 103 J
100 g of water is heated from 30oC to 50oC. Ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is 4184 J/kg/K)
4.2 kJ
8.4 kJ
84 kJ
P-V plots for two gases during an adiabatic processes are shown in figure. Plots 1 and 2 should correspond respectively to
He and O2
O2 and He
He and Ar
O2 and N2
The efficiency of a Carnot engine operating between temperatures of 100oC and -23oC will be
