Thermodynamics Set 16

Mechanical Engineering

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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Thermodynamics Set 16

Q1 | For water which of the following will be reduced to zero at critical pressure?
  • Specific volume
  • Enthalpy
  • Internal energy
  • Latent heat of vaporisation
  • None of the above
Answer: Latent heat of vaporisation
Q2 | In case of centrifugal compressors, the phenomenon of air stream not able to follow the blade contour of an axial compressor is known as
  • Stalling
  • Feedback
  • Regeneration
  • Recirculation
  • Surging
Answer: Stalling
Q3 | If the rate of heat flow in aboves case remains constant, the ratio of temperature difference (?t1) (?t2) would be
  • 16 ; 1
  • 1 ; 4
  • 8 ; 1
  • 1 ; 16
  • 1 ; 8
Answer: 16 ; 1
Q4 | The ratio of heat flow QA/QB from two walls of same thickness having thermal conductivity kA = 2 kB, for the same temperature difference will be
  • 1
  • 2
  • 0.5
  • None of the above
Answer: 2
Q5 | Adiabatic bulk modulus is Y times the isothermal bulk modulus
  • Pulsejet
  • for liquids only
  • for real gases only
  • for perfect gases only
  • for all fluids
Answer: for all fluids
Q6 | A fusible plug is utilised when
  • Impurities in water are excessive
  • Water level is too low
  • Water level is too high
  • Firing rate is high
  • Steam generation rate is high
Answer: Water level is too low
Q7 | A carnot cycle engine operating between temperature range of 50?C and 100?C will have the efficiency of nearly
  • 50%
  • 26.80%
  • 13.40%
  • Pulsejet
  • 40%
Answer: 13.40%
Q8 | Free piston engines find application in
  • Compression air supply
  • Mining installation
  • Gas turbines
  • supercharging reciprocating engines
  • None of the above
Answer: Gas turbines
Q9 | For a pure substance at its triple point, the number of degrees of freedom is
  • 0
  • 1
  • 2
  • None of the above
  • Pulsejet
Answer: 0
Q10 | A control volume refers to
  • An isolated system
  • A specified mass
  • A fixed region in space
  • A closed system
  • A reversible process only
Answer: A fixed region in space
Q11 | In an adiabatic change the system
  • Heat taken from surroundings is exactly equal to heat rejected to surroundings
  • Exchanges no heat with the surroundings
  • Gives heat to the surrounding
  • Partly takes heat and partly leaves to the surroundings
  • Takes heat from the surroundings
Answer: Exchanges no heat with the surroundings
Q12 | In case of axial flow compressors for minimum fluid driction and blade tip clearance losses, the blades of an axial flow compressor are disigned for
  • 53% reaction
  • 90% reaction
  • 60% reaction
  • Less than 50% reaction
  • 75% reaction
Answer: 53% reaction
Q13 | If the temperature of the source is increased, the efficiency of the Carnot engine
  • Will be equal to the efficiency of a practical engine
  • Increases
  • Does not change
  • Depends on their factors
  • Decreases
Answer: Increases
Q14 | In Porous plug experiment the change in temperature of a gas depends upon
  • its molecular weight
  • its specific heat
  • pressure gradient on either side
  • All of the above
  • Pulsejet
Answer: pressure gradient on either side
Q15 | What two dissimilar metals are heated at one end cooled at the other c.m.f. is developed proportional to difference of temperatures at two ends". Which of the following name is associated with the above statement?
  • Euler
  • Peltier-Thomson
  • Gay-Lussac
  • Faraday
  • Kelvin-planck
Answer: Peltier-Thomson
Q16 | Which two cycles have one constant volume, one constant pressure and two adiabatic processes each?
  • Brayton and Joules cycle
  • Diesel and Dual cycles
  • Otto and Carnot cycles
  • Sterling and Diesel cycles
  • Pulsejet
Answer: Sterling and Diesel cycles
Q17 | If the door of a refrigerator in a room is left open, the temperature of the room will
  • decrease
  • Pulsejet
  • remain unaltered
  • increase
Answer: increase
Q18 | For the same heat inpur and same compression ratio
  • Otto cycle and Diesel cycle are equally efficient
  • Otto cycle is less efficient than diesel cycle
  • Efficiency depends mainly on working substance
  • None of the above
  • Rankine
Answer: None of the above
Q19 | In case of six stage compression of air for minimum work conditions
  • Pressure rise per stage will be equal
  • Cylinder volumes will be identical
  • Temperature rise in the cylinders will be the same
  • Work done in successive stages will be in geometrical progression
  • Piston diameters will be identical
Answer: Work done in successive stages will be in geometrical progression
Q20 | The value of characteristic gas constant in kg metre per kg per deg C as
  • 29.97
  • 1554
  • 848
  • 96
  • 53.3
Answer: 29.97
Q21 | The processes or systems that do not involve heat are called
  • Adiabatic processes
  • Steady processes
  • Equilibrium processes
  • Thermal processes
  • Isothermal processes
Answer: Adiabatic processes
Q22 | The vapour pressure of water at 30?C in pascals is
  • 0.44
  • 4315
  • 223
  • 431.5
  • 7.18
Answer: 4315
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