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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Thermodynamics Set 15
Q1 | An elastic sphere of 0.5 m diameter contains a gas at 115 k Pa. Heating of the sphere causes it to increase to 0.62 m and during the process the pressure is proportional to the sphere diameter. The work done by the gas will be
- 7.7 kJ
- Pulsejet
- 9.9 kJ
- 15 kJ
- 11 kJ
Q2 | Second law of theromodynamics defines
- Heat
- Entropy
- Work
- Internal energy
- Enthalpy
Q3 | In a reversible polytropic process
- The entropy remains constant
- Enthalpy remains constant
- Internal energy remains constant
- Some heat transfer occurs
- Temperature remains constant
Q4 | Entropy of the universe tends to
- Approximately zero
- A minimum
- A maximum
- No particular value as it remains constant
- Zero
Q5 | Isothermals are curves obtained by drawing
- P against T
- P against V
- V against T
- PV against T
- PV against V
Q6 | In an isothermal expansion of gases
- Temperature is lowered
- Temperature shows the extent of expansion
- Temperature becomes zero
- Temperature is unaltered
- Temperature is raised
Q7 | A machine that continuously creates its own energy is known as
- Perpetual motion machine of second kind
- Self-propelled machine
- 100% efficient machine
- Perpetual motion machine of first kind
- Reversible machine
Q8 | When a direct current is passed through a junction of two dissimilar metals, the junction becomes either cold or hot. The phenomenon is known as
- Faraday's law
- Peltier's effect
- Thompson effect
- Maxwell's effect
- Seeback's effect
Q9 | Brayton cycle cannot be used in reciprocating engines even for same adiabatic compression ratio and work output because
- Brayton cycle is for slow speed engines
- Brayton cycle is less efficient
- Brayton cycle requires large air-fuel ratio
- Otto cycle is more efficient
- Large volume of low pressure air cannot be efficiently handled in reciprocating engines
Q10 | Which of the following relations is not valid during throttling process?
- External work done = Zero
- Total heat = Constant
- Pressure drop = Zero
- Change in enthalpy = Zero
- Change in internal energy = Zero
Q11 | Two ideal engines A and B have their sources at 600 k and 400 k and their sinks at 300 k and 250 k respectively. What inference can be drawn about their efficiency
- A is more efficient than B
- A is less efficient than B
- The information given is incomplete
- Both are equally efficient
- Pulsejet
Q12 | A law which is applicable only to ideal vapours and liquids, that equates the equilibrium partial pressures of a solution component in the coexisting phases, is known as
- Maxwell's equation
- Roult's law
- Henry's law
- Fick's law
- Joule's law
Q13 | A barn is
- A unit of area
- A unit of length
- A unit of time
- A unit of mass
- None of the above
Q14 | Highly polished surfaces of a thermosflask prevent heat by
- Convection
- Radiation
- Conduction
- microns
Q15 | As we go up in air the temperature of air decreases because
- Pulsejet
- winds help in heat transfer by convection
- of low pressure of air
- oxygen content of air decreases sharply
- heating effect due to infra red radiations from the surface of the earth is reduced
Q16 | According to kinetic theory of heat
- Temperature should rise during boiling
- Temperature should fall during freezing
- At low temperatures all bodies are in solid state
- At absolute zero there is absolute no vibration of molecules
- None of the above
Q17 | Balanced draft incorporates
- Forced draft
- Induced draft
- Forced and induced draft
- Chimney draft only
- None of the above
Q18 | The internal energy of an ideal gas is
- A function of temperature alone
- A function of pressure
- A function of volume
- (a) and (b) only
- All the above
Q19 | In any process the maximum amount of mechanical energy that can be converted to heat
- Depends upon the intake and exhaust temperature
- Is 50%
- Depends upon the amount of friction
- Depends upon whether kinetic energy is involved
- Is 100%
Q20 | The characteristic equation of gases pv = nRT holds good for
- Real gases
- Monoatomic gases
- Diatomic gases
- Ideal gases
- Mixture of gases
Q21 | The external work donw is zero all the following cases EXCEPT
- Pulsejet
- Constant volume
- Isothermal
- Free expansiton
- Throttling
Q22 | If a process can be stopped at any stage and reversed so that the system and surroundings are exactly restored to their initial states, it is known as
- Isothermal process
- Thermodynamic process
- Ideal process
- Adiabatic process
- Reversible process
Q23 | Which of the following does not change during an-ideal throttling process?
- Pressure, volume and temperature
- Enthalpy
- Pressure and volume
- Temperature and pressure
- Enthalpy and temperature
Q24 | The process in which no heat enters or leaves the system is called
- Isobaric
- Isothermal
- Isentropic
- Isochoric
- None of the above
Q25 | Which is incorrect statement about the reversible process?
- A reversible process is ideal
- A reversible process must pass through a continuous series of equilibrium states
- A reversible process when undone, will leave no history of the events in the surroundings
- A reversible process must pass through the same states on the reversed path as were initially visited on the forward path
- None of the above