Thermodynamics (Physics) · Question 25

A monatomic gas at a pressure P, having a volume V expands isothermally to a volume 2V and then adiabatically to a volume 16V. The final pressure of the gas is (Take = 5/3)

1. 64P
2. 32P
3. P/64
4. 16P

A thermodynamic system undergoes cyclic process ABCDA as shown in figure. The work done by the system in the cycle is [figure]

1. P0V0
2. 2P0V0
3. P0V02
4. zero

The molar specific heats of an ideal gas at constant pressure and volume are denoted by Cp and Cv, respectively. If = CpCv and R is the universal gas constant, then Cv is equal to

1. ( - 1)R
2. R
3. 1 + 1 -
4. R( - 1)

A gas is taken through the cycle A B C A, as shown. What is the net work done by the gas? [figure]

1. Zero
2. - 2000 J
3. 2000 J
4. 1000 J

During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its temperature. The ratio of CpCv for the gas is

1. 53
2. 32
3. 43
4. 2

A system is taken from state a to state c by two paths adc and abc as shown in the figure. The internal energy at a is Ua = 10 J. Along the path adc the amount of heat absorbed dQ1 = 50 J and the work obtained dW1 = 20 J whereas along the path abc the heat absorbed dQ2 = 36 J. The amount of work along the path abc is [figure]

1. 10 J
2. 12 J
3. 36 J
4. 6 J

Which of the following relations does not give the equation of an adiabatic process, where terms have their usual meaning?

1. P1- T = constant
2. PV = constant
3. TV -1 = constant
4. P T1- = constant

Two Carnot engines A and B are operated in series. The engine A receives heat from the source at temperature T1 and rejects the heat to the sink at temperature T. The second engine B receives the heat at temperature T and rejects to its sink at temperature T2. For what values of T the efficiencies of the two engines are equal

1. T1 - T22
2. T1T2
3. T1T2
4. T1 + T22

An ideal gas goes from state A to state B via three different processes as indicated in the P-V diagram. [figure] If Q1, Q2, Q3 indicate the heat absorbed by the gas along the three processes and U1, U2, U3 indicate the change in internal energy along the three processes respectively, then

1. Q1 > Q2 > Q3 and U1 = U2 = U3
2. Q3 > Q2 > Q1 and U1 = U2 = U3
3. Q1 = Q2 = Q3 and U1 > U2 > U3
4. Q3 = Q2 = Q1 and U1 > U2 > U3

One mole of an ideal gas goes from an initial state A to final state B via two processes : It first undergoes isothermal expansion from volume V to 3V and then its volume is reduced from 3V to V at constant pressure. The correct P-V diagram representing the two processes is

1. [figure]
2. [figure]
3. [figure]
4. [figure]