Thermodynamics (Physics) · Question 7

A vessel contains 0.15 m3 of a gas at pressure 8 bar and temperature 140 °C with cp=3R and cv=2R. It is expanded adiabatically till pressure falls to 1 bar. The work done during this process is kJ. (R is gas constant)

5 moles of unknown gas is heated at constant volume from 10 °C to 20 °C. The molar specific heat of this gas at constant pressure cp = 8 cal/mol.°C and R = 8.36 J/mol.°C. The change in the internal energy of the gas is calorie.

In the following p - V diagram the equation of state along the curved path is given by (V - 2)2 = 4ap where a is a constant. The total work done in the closed path is [figure]

1. + 13a
2. - 1a
3. 12a
4. - 13a

A thermodynamic system is taken through the cyclic process ABC as shown in the figure. The total work done by the system during the cycle ABC is J. [figure]

Densities of water at 4 and 20 are 1000 kg/m3 and 998 kg/m3 respectively. The increase in internal energy of 4 kg of water when it is heated from 4 to 20 is J. (specific heat capacity of water = 4.2 kJ/kg K and 1 atmospheric pressure = 105 Pa)

1. 268799.2
2. 315826.2
3. 234699.2
4. 258700.8

10 mole of an ideal gas is undergoing the process shown in the figure. The heat involved in the process from P1 to P2 is Joule (P1 = 21.7 Pa and P2 = 30 Pa, Cv = 21 J/K mol, R = 8.3 J/mol K). The value of is . [figure]

1. 21
2. 28
3. 24
4. 15

When 300 J of heat is given to an ideal gas with Cp = 72R, its temperature rises from 20 to 50 keeping its volume constant. The amount of the gas is (approximately) 10-3 mol. (R = 8.314 J/mol K)

One mole of an ideal diatomic gas expands from volume V to 2V isothermally at a temperature 27 and does W joule of work. If the gas undergoes same magnitude of expansion adiabatically from 27 doing the same amount of work W, then its final temperature will be (close to) . ( e 2 = 0.693)

1. -56
2. -117
3. -30
4. -189

The internal energy of a monoatomic gas is 3nRT. One mole of helium is kept in a cylinder having internal cross section area of 17 cm2 and fitted with a light movable frictionless piston. The gas is heated slowly by supplying 126 J heat. If the temperature rises by 4 , then the piston will move cm. (atmospheric pressure = 105 Pa)

1. 1.55
2. 14.5
3. 15.5
4. 1.45

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