Thermodynamics (Physics)

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the correct answer from the options given below:

1. (A) is true but (R) is false
2. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
3. (A) is false but (R) is true
4. Both (A) and (R) are true and (R) is the correct explanation of (A)

A poly-atomic molecule (CV=3R, CP=4R, where R is gas constant) goes from phase space point A ( PA=105 Pa, VA=4 10-6 m3 ) to point B ( PB=5 104 Pa, VB=6 10-6 m3 ) to point C ( PC=104 Pa, VC=8 10-6 m3 ). A to B is an adiabatic path and B to C is an isothermal path. The net heat absorbed per unit mole by the system is : [figure]

1. 500R( 3+ 4)
2. 450R( 4- 3)
3. 500R 2
4. 400R 4

A Carnot engine (E) is working between two temperatures 473 K and 273 K. In a new system two engines - engine E1 works between 473 K to 373 K and engine E2 works between 373 K to 273 K. If 12, 1 and 2 are the efficiencies of the engines E, E1 and E2, respectively, then

1. 12 = 1 2
2. 12 = 1 + 2
3. 12 1 + 2
4. 12 < 1 + 2

An ideal gas goes from an initial state to final state. During the process, the pressure of gas increases linearly with temperature. Choose the correct answer from the options given below:

1. A, C Only
2. A, D, E Only
3. E Only
4. A, B, C, D Only

The temperature of 1 mole of an ideal monoatomic gas is increased by 50 at constant pressure. The total heat added and change in internal energy are E1 and E2, respectively. If E1E2= x9 then the value of x is .

The magnitude of heat exchanged by a system for the given cyclic process ABCA (as shown in figure) is (in SI unit) : [figure]

1. zero
2. 40
3. 5
4. 10

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the correct answer from the options given below :

1. Both (A) and (R) are true and (R) is the correct explanation of (A)
2. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
3. (A) is false but (R) is true
4. (A) is true but (R) is false

Match List - I with List - II Choose the correct answer from the options given below:

1. A-I, B-III, C-II, D-IV
2. A-I, B-IV, C-II, D-III
3. A-III, B-I, C-IV, D-II
4. A-III, B-IV, C-I, D-II

An ideal gas initially at 0 temperature, is compressed suddenly to one fourth of its volume. If the ratio of specific heat at constant pressure to that at constant volume is 3/2, the change in temperature due to the thermodynamic process is K.

Water of mass m gram is slowly heated to increase the temperature from T1 to T2. The change in entropy of the water, given specific heat of water is 1 J kg-1 K-1, is :

1. m(T2-T1)
2. zero
3. m ( T1T2 )
4. m ( T2T1 )

[figure] Using the given P-V diagram, the work done by an ideal gas along the path ABCD is :

1. 3P0 V0
2. -3P0 V0
3. -4P0 V0
4. 4P0 V0

Given are statements for certain thermodynamic variables, Choose the correct answer from the options given below :

1. C and D Only
2. A and B Only
3. D and A Only
4. B and C Only

The volume of an ideal gas ( = 1.5) is changed adiabatically from 5 litres to 4 litres. The ratio of initial pressure to final pressure is :

1. 45
2. 85 5
3. 2 5
4. 1625

A sample of 1 mole gas at temperature T is adiabatically expanded to double its volume. If adiabatic constant for the gas is = 32, then the work done by the gas in the process is :

1. RT[2 + 2]
2. RT[2 - 2]
3. RT[2 - 2]
4. TR[2 + 2]

A real gas within a closed chamber at 27 undergoes the cyclic process as shown in figure. The gas obeys PV3 = RT equation for the path A to B. The net work done in the complete cycle is (assuming R = 8 J/mol K): [figure]

1. -20 J
2. 205 J
3. 225 J
4. 20 J

Two different adiabatic paths for the same gas intersect two isothermal curves as shown in P-V diagram. The relation between the ratio VaVd and the ratio VbVc is: [figure]

1. VaVd VbVc
2. VaVd = ( VbVc )-1
3. VaVd = VbVc
4. VaVd = ( VbVc )2

A diatomic gas ( = 1.4) does 100 J of work in an isobaric expansion. The heat given to the gas is :

1. 150 J
2. 490 J
3. 350 J
4. 250 J

The specific heat at constant pressure of a real gas obeying PV2 = RT equation is:

1. R
2. CV + R
3. CV + R2V
4. R3 + CV

A total of 48 J heat is given to one mole of helium kept in a cylinder. The temperature of helium increases by 2 C. The work done by the gas is: Given, R = 8.3 J K-1 mol-1.

1. 23.1 J
2. 48 J
3. 24.9 J
4. 72.9 J

The heat absorbed by a system in going through the given cyclic process is : [figure]

1. 61.6 J
2. 431.2 J
3. 19.6 J
4. 616 J

During an adiabatic process, if the pressure of a gas is found to be proportional to the cube of its absolute temperature, then the ratio of CPCV for the gas is :

1. 53
2. 32
3. 75
4. 97

A sample of gas at temperature T is adiabatically expanded to double its volume. Adiabatic constant for the gas is = 3/2. The work done by the gas in the process is: ( = 1 mole)

1. RT[2 2 - 1]
2. RT[2 - 2]
3. RT[1 - 2 2]
4. RT[ 2 - 2]

The pressure and volume of an ideal gas are related as PV3/2 = K (Constant). The work done when the gas is taken from state A (P1, V1, T1 ) to state B (P2, V2, T2 ) is :

1. 2 (P2 V2 - P1 V1 )
2. 2 ( P1 V1 - P2 V2 )
3. 2 (P2V2 - P1V1 )
4. 2 (P1V1 - P2V2 )

A diatomic gas ( =1.4) does 200 J of work when it is expanded isobarically. The heat given to the gas in the process is :

1. 800 J
2. 600 J
3. 700 J
4. 850 J

The given figure represents two isobaric processes for the same mass of an ideal gas, then [figure]

1. P2>P1
2. P1>P2
3. P1=P2
4. P2 P1

Two thermodynamical processes are shown in the figure. The molar heat capacity for process A and B are CA and CB. The molar heat capacity at constant pressure and constant volume are represented by CP and CV, respectively. Choose the correct statement. [figure]

1. CP>CB>CA>CV
2. CP>CV>CA=CB
3. CA=0 and CB=
4. CA= , CB=0

Choose the correct statement for processes A & B shown in figure. [figure]

1. PV=k for process B and A.
2. P -1T =k for process B and T=k for process A.
3. T P -1=k for process A and PV=k for process B.
4. PV =k for process B and PV=k for process A.

A thermodynamic system is taken from an original state A to an intermediate state B by a linear process as shown in the figure. Its volume is then reduced to the original value from B to C by an isobaric process. The total work done by the gas from A to B and B to C would be : [figure]

1. 800 J
2. 2200 J
3. 33800 J
4. 1200 J

0.08 kg air is heated at constant volume through 5 . The specific heat of air at constant volume is 0.17 kcal/kg C and J=4.18 joule/cal. The change in its internal energy is approximately.

1. 318 J
2. 298 J
3. 284 J
4. 142 J

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

1. 75
2. 32
3. 97
4. 53