Engineering Thermodynamics Set 19

Mechanical Engineering

Practice Mode Previous Next
On This Page

This set of Engineering Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Engineering Thermodynamics Set 19

Q1 | A reversible cycle has following processes.
  • 4 isothermal processes
  • 4 adiabatic processes
  • 2 isothermal and 2 adiabatic processes
  • none of the mentioned
Answer: 2 isothermal and 2 adiabatic processes
Q2 | 2 STATEMENTS OF SECOND LAW AND ITS COROLLARIES. CARNOT CYCLE REVERSED CARNOT CYCLE, PERFORMANCE. CLAUSIUS INEQUALITY.
  • high, low, receives
  • low, high, receives
  • high, low, gives
  • low, high, gives
Answer: low, high, receives
Q3 | According to Carnot’s theorem, all heat engines operating between a given constant temperature source and sink, none has a higher efficiency than a reversible engine.
  • true
  • false
Answer: true
Q4 | The efficiency of all reversible heat engines operating between the same heat reservoirs is
  • same
  • independent of the nature of working substance
  • independent of the amount of working substance
  • all of the mentioned
Answer: all of the mentioned
Q5 | For a reversible heat pump, COP is given by
  • t2/(t1-t2)
  • t1/(t1-t2)
  • t2/(t2-t1)
  • t1/(t2-t1)
Answer: t1/(t1-t2)
Q6 | The entropy of an isolated system can never          
  • increase
  • decrease
  • be zero
  • none of the mentioned
Answer: decrease
Q7 | According to entropy principle, the entropy of an isolated system can never decrease and remains constant only when the process is reversible.
  • true
  • false
Answer: true
Q8 | Entropy may decrease locally at some region within the isolated system. How can this statement be justified?
  • this cannot be possible
  • this is possible because entropy of an isolated system can decrease.
  • it must be compensated by a greater increase of entropy somewhere within the system.
  • none of the mentioned
Answer: it must be compensated by a greater increase of entropy somewhere within the system.
Q9 | The final temperatures of two bodies, initially at T1 and T2 can range from
  • (t1-t2)/2 to sqrt(t1*t2)
  • (t1+t2)/2 to sqrt(t1*t2) c) (t1+t2)/2 to (t1*t2)
  • d) (t1-t2)/2 to (t1*t2)
Answer: (t1+t2)/2 to sqrt(t1*t2) c) (t1+t2)/2 to (t1*t2)
Q10 | The part of          available for conversion is referred to          
  • high grade energy, available energy
  • low grade energy, available energy
  • low grade energy, unavailable energy
  • high grade energy, unavailable energy
Answer: low grade energy, available energy
Q11 | The          obtainable from a certain heat input in a cyclic heat engine is called          
  • minimum work output, available energy
  • maximum work output, available energy
  • minimum work input, unavailable energy
  • none of the mentioned
Answer: maximum work output, available energy
Q12 | 4 APPLICATIONS OF II LAW. HIGH AND LOW GRADE ENERGY.
  • true
  • false
Answer: true
Q13 | The available energy is known as          and the unavailable energy is known as          
  • energy, exergy
  • exergy, energy
  • both are called exergy
  • both are called energy
Answer: exergy, energy
Q14 | Whenever heat is transferred through a finite temperature difference, there is always a decrease in the availability of energy so transferred.
  • true
  • false
Answer: true
Q15 | Any thermodynamic process is accompanied by entropy generation.
  • true
  • false
Answer: true
Q16 | The rate of entropy increase of the control volume          or          the net rate of entropy transfer to it.
  • exceeds or is less than
  • exceeds, is equal to
  • is less than, or equal to
  • none of the mentioned
Answer: exceeds, is equal to
Q17 | The rate at which entropy is transferred out must          the rate at which entropy enters the control volume.
  • be less than
  • equal to
  • exceed
  • none of the mentioned
Answer: exceed
Q18 | The first law efficiency is defined as the ratio of the output energy to the input energy.
  • true
  • false
Answer: true
Q19 | With the concept of exergy available, which of the following is possible?
  • to analyse means of minimizing the consumption of available energy to perform a given process
  • to ensure most efficient possible conversion of energy
  • both of the mentioned
  • none of the mentioned
Answer: both of the mentioned
Q20 | If work is involved, Amin=          and if heat is involved, Amin=          
  • w, q(1+to/t)
  • w, q(1-to/t)
  • q(1+to/t), w
  • q(1-to/t), w
Answer: w, q(1-to/t)
Q21 | If solar energy Qr is available at a reservoir storage temperature of Tr and if quantity of heat Qa is transferred by the solar collector at temperature Ta, then which of the following is true?
  • first law efficiency = qa/qr
  • second law efficiency = exergy output / exergy input
  • second law efficiency = (first law efficiency)*(1-to/ta)/(1-to/tr)
  • all of the mentioned
Answer: all of the mentioned
Q22 | For proper utilization of exergy, it is desirable to make first law efficiency           and the source and use temperatures should
  • as close to unity, be different
  • as close to unity, match
  • as close to zero, match
  • as close to zero, be different
Answer: as close to unity, match
Q23 | The slopes of sublimation and vaporization curves for all substances are
  • negative
  • positive
  • zero
  • none of the mentioned
Answer: positive
Q24 | When does a vapour become superheated?
  • when the temperature of vapour is less than the saturation temperature at given pressure
  • when the temperature of vapour is more than the saturation temperature at given pressure
  • when the temperature of vapour is equal to the saturation temperature at given pressure
  • none of the mentioned
Answer: when the temperature of vapour is more than the saturation temperature at given pressure
Q25 | The properties of liquid            with pressure.
  • do not vary
  • vary largely
  • vary little
  • none of the mentioned
Answer: vary little
Previous Next