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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