Thermodynamics (Physics) · Question 16

The volume of an ideal gas increases 8 times and temperature becomes (1/4)th of initial temperature during a reversible change. If there is no exchange of heat in this process ( Q = 0) then identify the gas from the following options (Assuming the gases given in the options are ideal gases) :

1. NH3
2. O2
3. CO2
4. He

10 mole of oxygen is heated at constant volume from 30 to 40 . The change in the internal energy of the gas is cal. (The molecular specific heat of oxygen at constant pressure, CP = 7 cal/mol C and R = 2 cal/mol C.)

A diatomic gas ( = 1.4) does 100 J of work when it is expanded isobarically. Then the heat given to the gas J.

A monoatomic gas having = 53 is stored in a thermally insulated container and the gas is suddenly compressed to ( 18 )th of its initial volume. The ratio of final pressure and initial pressure is: ( is the ratio of specific heats of the gas at constant pressure and at constant volume)

1. 16
2. 32
3. 28
4. 40

An ideal gas has undergone through the cyclic process as shown in the figure. Work done by the gas in the entire cycle is 10-1 J. (Take = 3.14) [figure]

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

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

Match List - I with List - II. Q = Heat supplied W = Work done by the system U = Change in internal energy P = Pressure of the system V = Change in volume of the system Choose the correct answer from the options given below :

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

A gas is kept in a container having walls which are thermally non-conducting. Initially the gas has a volume of 800 cm3 and temperature 27 . The change in temperature when the gas is adiabatically compressed to 200 cm3 is: (Take = 1.5; is the ratio of specific heats at constant pressure and at constant volume)

1. 300 K
2. 600 K
3. 327 K
4. 522 K

During the melting of a slab of ice at 273 K at atmospheric pressure :

1. Internal energy of ice-water system remains unchanged.
2. Positive work is done by the ice-water system on the atmosphere.
3. Positive work is done on the ice-water system by the atmosphere.
4. Internal energy of the ice-water system decreases.

[figure] A piston of mass M is hung from a massless spring whose restoring force law goes as F = -kx3, where k is the spring constant of appropriate dimension. The piston separates the vertical chamber into two parts, where the bottom part is filled with 'n' moles of an ideal gas. An external work is done on the gas isothermally (at a constant temperature T) with the help of a heating filament (with negligible volume) mounted in lower part of the chamber, so that the piston goes up from a height L0 to L1, the total energy delivered by the filament is: (Assume spring to be in its natural length before heating)

1. nRT ( L1L0 ) + Mg(L1 - L0) + 3k4 (L14 - L04 )
2. nRT ( L1L0 ) + Mg(L1 - L0) + k4 (L14 - L04 )
3. nRT ( L12L02 ) + Mg2(L1 - L0) + k4 (L14 - L04 )
4. 3nRT ( L1L0 ) + 2Mg(L1 - L0) + k3 (L13 - L03 )