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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Thermodynamics Set 6

Q1 | A substance above critical temperature exists as
  • Solid
  • Liquid
  • Gas
  • Unsaturated vapour
  • Any of the above
Q2 | In the above problem work done is equal to
  • 130 kcal
  • 150 kcal
  • 100 kcal
  • 80 kcal
  • 180 kcal
Q3 | In a boiler a fusible plug is located at the
  • Pulsejet
  • inlet to stop valve
  • top of superheater
  • bottom of drum
  • bottom of fire tubes
Q4 | For maximum specific output of a constant volume cycle
  • The working fluid should be air
  • The speed should be high
  • Suction temperature should be high
  • Temperature of the working fluid at the end of compression and expansion should be equal
  • Exhaust pressure should be high
Q5 | A frictionless heat engine can be 100% efficient only if its exhaust temperature is
  • Equal to its input temperature
  • Less than its input temperature
  • 0?K
  • ?100?C
  • 0?C
Q6 | In steam tables, the entropy is shown as zero for
  • saturated liquid at 0?C
  • saturated vapours at atmospheric pressure
  • Pulsejet
  • saturated vapour at 0?C
  • saturated liquid at atmospheric pressure
Q7 | When a gas is to be stored, the type of compression that would be ideal is
  • Isothermal
  • Adiabatic
  • Polytropic
  • Constant pressure
  • None of the above
Q8 | Diffusion is
  • Mixing of two portions of fluid
  • Mixing of a gas in two containers at different pressures
  • Mixing of two portions of a fluid at different temperatures
  • Mixing of unlike fluids
  • None of the above
Q9 | In case the temperature of a hot body is increased by 50%, the amount of radiation emitted by it would increase by nearly
  • 250%
  • 500%
  • Pulsejet
  • 50%
  • 125%
Q10 | The efficiency of cycle would be
  • 66.7 percent
  • 100 percent
  • 88.8 percent
  • 37.7 percent
  • 78.3 percent
Q11 | If the temperature of the sink is decreased, the efficiency of a Carnot engine
  • remain unaffected
  • first increased and then decreases
  • Pulsejet
  • decreases
  • increases
Q12 | When a gas is to be stored, the type of compression that would be ideal is
  • Isothermal
  • Adiabatic
  • Polytropic
  • Constant volume
  • None of the above
Q13 | According to Lussac's law for perfect gases, the absolute pressure of given mass varies directly as
  • Temperature
  • Absolute temperature
  • Absolute temperature in case the volume remains constant
  • The product of volume and absolute temperature
  • None of the above
Q14 | Gibbs free energy G is given by
  • G = T . H . s.
  • G = H/Ts
  • Pulsejet
  • G = H - Ts
  • G = H + Ts
Q15 | A sterling cycle consists of
  • Two isothermal and two adiabatic processes
  • Two constant volume and two constant pressure processes
  • Two adiabatic and two isentropic processes
  • Two isothermal and two constant volume processes
  • Two adiabatic and two constant pressure processes
Q16 | A reversible process requires that
  • Newton's law of viscosity be satisfied
  • There whould be no viscous or coulomb friction in the system
  • Heat transfer occurs from surrounding to system only
  • Temperature of system and surroundings be equal
  • There be no heat transfer
Q17 | The area of pv diagram for a Carnot cycle represents
  • Enthalpy drop
  • Volume and pressure ratios.
  • Temperature drop
  • Work done
  • Total heat supplied
Q18 | An adlabatic wall permits
  • Heat exchange by all the three modes of heat transfer
  • No heat exchange
  • Radiation heat flow only
  • Convective heat flow only
  • Conduction heat flow only
Q19 | The melting point of ice
  • Pulsejet
  • decreases with increase in atmospheric pressure
  • increases with increase in atmospheric pressure
  • is independent of atmospheric pressure
Q20 | In an isothermal process change in internal energy
  • Depends on the friction and other factors
  • Becomes zero
  • Remains constant
  • Decreases
  • Increases
Q21 | When two gases are not under the same conditions of temperature and pressure, upon mixing there will be
  • loss of entropy to the surroundings
  • exchange of entropy between the two gases
  • increase in available heat but decrease in unavailable heat
  • None of the above
  • Pulsejet
Q22 | The dew point temperature of humid air is
  • the temperature of air obtained on cooling it till saturation at constant volume
  • Pulsejet
  • always higher than the wet bulb temperature
  • the temperature of air obtained on cooling it till saturation at constant pressure
  • never lower than the wet bulb temperature
Q23 | Which one of the following is heterogeneous system
  • Cooking gas in a cylinder
  • The cooling fluid in the radiator
  • A mixture of hydrogen and oxygen
  • Atmospheric air
  • A mixture of ice, water and system.
Q24 | The value of characteristic gas constant for carbon dioxide would be
  • 19.28 kg/metre/kg/?K
  • 30.4 kg/metre/kg/?K
  • 29.2 kg/metre/kg/?K
  • 16.1 kg/metre/kg/?K
  • 10.0 kg/metre/kg/?K
Q25 | In case of centrifugal compressors the phenomenon of fixed mass flow rate in compressor regardless of pressure ratio is known as
  • Choking
  • Stalling
  • Recirculation
  • Surging
  • Regeneration