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
An ideal gas is compressed adiabatically to 8/27 times of its present value at 27oC. The temperature of the gas becomes (γ= 5/3).
475oC
275oC
402oC
175oC
The internal energy change, when a system goes from state A to B is 40 kJ mole-1. If the system goes from A to B by a reversible path and returns to state A by an irreversible path, what would be the net change in internal energy ?
40 kJ
> 40 kJ
< 40 kJ
zero
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
9/7
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
325 K
250 K
380 K
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 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
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
7900 J
Which of the following statement is correct for any thermodynamic system ?
The internal energy changes in all processes
Internal energy and entopy are state functions
The change in entropy can never be zero
The work done in an adiabatic process is always zero.
In an adiabatic system which is true ?
PγTγ-1 = constant
PγT1-γ = constant
PTγ = constant
P1-γTγ = constant
