# Thermodynamic Processes

## Trending Questions

**Q.**The relation between internal energy U, pressure P and volume V of a gas in an adiabatic process is U=a+bPV, where a and b are constants. What is the effective value of adiabatic constant γ?

- ab
- b+1b
- a+1a
- ba

**Q.**A diatomic gas (γ=1.4) of mass m at a pressure of 2 atmospheres is compressed adiabatically so that its temperature rises from 27∘C to 927∘C. The pressure of the gas in final state is

- 256 atm
- 8 atm
- 68.7 atm
- 28 atm

**Q.**

An engine operates by taking a monatomic ideal gas through the cycle shown in the figure. An engine operates by taking a monatomic ideal gas through the cycle shown in the figure. The percentage efficiency of the engine is close to __________.

**Q.**P−V plots for two gases during adiabatic processes are shown in Fig. Plots 1 and 2 should correspond respectively to

- O2 and He
- He and Ar
- O2 and N2
- He and O2

**Q.**The slopes of isothermal and adiabatic curves are related as

(a) Isothermal curve slope = adiabatic curve slope

(b) Isothermal curve slope = γX adiabatic curve slope

(c) Adiabatic curve slope = γX isothermal curve slope

(d) Adiabatic curve slope = 12X isothermal curve slope

- a
- b
- c
- d

**Q.**Three moles of an ideal gas are taken through a cyclic process ABCA as shown in T−V indicator diagram. The gas loses 2510 J of heat in the complete cycle. If TA=100 K and TB=200 K, the work done by the gas during the process BC is (line AB if extended passes through origin)

- 5000 J
- −5000 J
- 4000 J
- −2500 J

**Q.**Figure shows a curve on logT and logV scale, when an ideal gas is undergoing an adibatic process. The gas is

- Monatomic
- Diatomic
- Polyatomic
- Mixture of monatomic and diatomic

**Q.**The molar heat capacity in a process of a diatomic gas, if it does a work of Q4, when a heat of Q is supplied to it is

- 25R
- 103R
- 52R
- 67R

**Q.**3 moles of an ideal monoatomic gas perfoms a cycle shown in the figure. The gas temperature at A, B, C, D are TA=400 K, TB=800 K, TC=2400 K, TD=1200 K. Find the work done by the gas.

- 12 kJ
- 20 kJ
- 24 kJ
- 120 kJ

**Q.**An ideal gas has initial volume V and pressure p. If the volume of gas is doubled during expansion, then minimum work will be done in which thermodynamic process ?

- Isobaric process
- Isothermal process
- Adiabatic process
- Same in all alone given process

**Q.**During an experiment an ideal gas is found to obey the condition P2ρ=constant [ρ is the density of the gas]. The gas is initially at temperature T, pressure P and density ρ. If the gas expands such that density changes to ρ2 , then choose the correct answer(s).

- Pressure of the gas changes to √2P
- The temperature of the gas changes to √2T
- The P−T Indicator diagram of the above process is a parabola.
- The P−T Indicator diagram of the above process is a Rectangular hyperbola.

**Q.**

A typical dorm room or bedroom contains about 2500 moles of air. Find the change in the internal energy of this much air when it is cooled from 35.0∘C to 26.0∘C at a constant pressure of 1.00 atm. Treat the air as an ideal gas with γ = 1.400.

**Q.**A mixture of hydrogen and oxygen has volume 500 cm3, temperature 300 K, pressure 400 kPa and mass 0.76 g. The ratio of masses of oxygen to hydrogen will be

- 16:3
- 3:16
- 8:3
- 3:8

**Q.**Heat is supplied to a diatomic gas at a constant pressure. The ratio of ΔQ:ΔU:ΔW is

- 5:3:2
- 5:2:3
- 7:5:2
- 7:2:5

**Q.**In an adiabatic process, pressure is increased by 23%. If CPCV=32, then the volume decreases by about

- 49%
- 23%
- 4%
- 94%

**Q.**If a gas is taken from A to C through B, then heat absorbed by the gas is 8 J. Heat absorbed by the gas in taking it directly from A to C is

- +8 J
- +9 J
- +5 J
- +7 J

**Q.**If heat is given to an ideal gas at constant pressure, then select the graph which best represents the variation of VT with temperature (T).

**Q.**An ideal monatomic gas at 300 K expands adiabatically to 8 times its volume. What is the final temperature?

- 300 K
- 75 K
- 560 K
- 340 K

**Q.**

What will be the average value of energy along one degree of freedom for an ideal gas in thermal equilibrium at a temperature $\mathrm{T}$ ? (${\mathrm{k}}_{\mathrm{B}}$ is Boltzmann constant)

${\mathrm{K}}_{\mathrm{B}}\mathrm{T}$

$\frac{2}{3}{\mathrm{K}}_{\mathrm{B}}\mathrm{T}$

$\frac{3}{2}{\mathrm{K}}_{\mathrm{B}}\mathrm{T}$

$\frac{1}{2}{\mathrm{K}}_{\mathrm{B}}\mathrm{T}$

**Q.**

Why is the work done in a reversible process maximum?

**Q.**Pressure versus temperature graphs of an ideal gas are as shown in figure. Choose the wrong statement

- Density of gas is constant in graph (iii)
- Density of gas is increasing in graph (i)
- Density of gas is decreasing in graph (ii)
- None of these

**Q.**

Why Gibbs free energy is called free energy?

**Q.**P−V diagram of a diatomic gas is a straight line passing through origin. What is the molar heat capacity of the gas during the process?

- R
- 2R
- 3.33R
- 3R

**Q.**In which process, the PV indicator diagram is a straight line parallel to volume axis?

- Isothermal
- Isobaric
- Irreversible
- Adiabatic

**Q.**An ideal gas at 27∘C is compressed adiabatically to 827 of its originalvolume. If γ=53, then the rise in temperature is

- 225 K
- 405 K
- 375 K
- 450 K

**Q.**Bursting of a tyre is an example of which of the following processes?

- Isobaric
- Adiabatic
- Isochoric
- Isothermal

**Q.**An ideal gas undergoes a cyclic process abcda which is shown by the pressure - density curve.

- Work done by the gas in the process bc is zero.
- Work done by the gas in the process cd is negative.
- Internal energy of the gas in state a is greater than in state c.
- Net work done by the gas in the cycle is negative.

**Q.**105 calories of heat is required to raise the temperature of 3 moles of an ideal gas at constant pressure from 30∘C to 35∘C. The amount of heat required in calories to raise the temperature of the gas from 60∘C to 65∘C at constant volume is [γ=CPCV=1.4]

- 50 cal
- 75 cal
- 70 cal
- 90 cal

**Q.**Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature T0, while box B contains one mole of helium at temperature (73)T0. The boxes are then put into thermal contact with each other, and heat flows between them until the gases reach a common final temperature (Ignore the heat capacity of boxes). Then, the final temperature of the gases, Tf in terms of T0 is -

- Tf=37T0
- Tf=73T0
- Tf=32T0
- Tf=52T0

**Q.**One mole of an ideal monoatomic gas is taken from A to C along the path ABC. The temperature of the gas at A is T0. For the process ABC, which one of the following option(s) is/are correct?

- Work done by the gas is RT0.
- Change in internal energy of the gas is 112RT0.
- Heat absorbed by the gas is 112RT0.
- Heat absorbed by the gas is 132RT0.