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This set of Engineering Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Engineering Thermodynamics Set 4
Q1 | Second law of thermodynamics defines
- a) work
- b) heat
- c) entropy
- d) internal energy
Q2 | For storing a gas which one of the following types of compression will beideal
- a) constant volume
- b) polytropic
- c) adiabatic
- d) isothermal
Q3 | A process which can be stopped at any stage & reversed so that the system & the surroundings are exactly restored to their initial states is known as
- a) thermodynamic process
- b) irreversible process
- c) reversible process
- d) isothermal process
Q4 | Which of the following is a reversibleprocess?
- a) throttling
- b) combustion
- c) free expansion
- d) extension &compression of a spring
Q5 | Leaking of air from a punctured tube is anexample of
- a) isothermal expansion
- b) adiabatic expansion
- c) throttling
- d) constant pressureexpansion
Q6 | To convert volumetric analysis to gravimetric analysis, the relative volume of each constituent of the flue gases is
- a) divided by its specific weight
- b) multiplied by its density
- c) multiplied by its molecular weight
- d) divided by its molecular weight
Q7 | a heat engine receives heat at the rate of 1500 kJ/min.& gives an output of 8.2 kW. Its thermal efficiency is equal to
- a) 20.5 %
- b) 30.2%
- c) 32.8%
- d) 44.6%
Q8 | An inventor claims that a new heat cycle will develop 0.4 kW for a heat addition of32.5 kJ/mm. The temperature of heat source is 1990 K & that of sink is 850K. Is his claim true?
- a) true
- b) false
- c) either of the above
- d) unpredictable
Q9 | Consider the following statements: The definition of1. temperature is due to zeroth law of thermodynamics2. entropy is due to first law of thermodynamics3. internal energy is due to second law of thermodynamics4. reversibility is due to Kelvin-Planck's ststement of these statements
- a) 1,2 & 3 are correct
- b) 1,3 & 4 are correct
- c) 1 alone is correct
- d) 2 alone is correct
Q10 | A heat engine is supplied with 250 kJ/s of heat at a constant fixed temperature of 227°C. The heat is rejected at 27°C. The cycle is reversible, if the amount of heat rejected is
- a) 273 kj/s
- b) 200 kj/s
- c) 180 kj/s
- d) 150 kj/s
Q11 | A Carnot engine receiving heat at 400K has an efficiency of 25%. The C.O.P. of a Carnot refrigerator working between the same temperature limits is
- a) 1
- b) 2
- c) 3
- d) 4
Q12 | If a heat enine gives an output of 3 kW when the input is 10,000 J/s, then the thermal efficiency of the engine will be
- a) 20%
- b) 30%
- c) 70%
- d) 76.7%
Q13 | The fundamental unit of enthalpy is
- a) mlt ????
- b) ml??t????
- c) ml??t ????
- d) ml??t ????
Q14 | In a cyclic heat engine operating between a source temperature of 600°C & a sink temperature of 20°C, the least rate of heat rejection per kW net output of theengine is
- a) 0.460 kw
- b) 0.505 kw
- c) 0.588 kw
- d) 0.650 kw
Q15 | In a reversible cycle, the source temperature is 227°C & the sink temperature is 27°C. The maximum available work for a heat input of 100 kJwill be
- a) 100 kj
- b) 60 kj
- c) 40 kj
- d) 88 kj
Q16 | A heat engine using lake water at 12° C as source & the surrounding atmosphere at 2°C as sink executes 1080 cycles per min. If the amount of heat drawn per cycle is 57J, then the output of the engine will be
- a) 66 w
- b) 56 w
- c) 46 w
- d) 36 w
Q17 | One reversible heat engine operates between 1600 K & T₂ K & another reversible heat engine operates between T₂ K & 400 K. If both the engines have the temperature T₂ must be equal to
- a) 100 kj
- b) 1200 k
- c) 1400 k
- d) 800 k
Q18 | An engine receives 15152 J/s of heat & produces 5 KW of power. The efficiencyof the engine is
- 25%
- 27.5%
- 30%
- 33%
Q19 | Choose the correct statement
- a) pressure, temp. & entropy are extensiveproperties
- b) pressure, temp. & entropy are intensiveproperties
- c) pressure, volume & temp. are extensive properties
- d) volume & entropy are extensive properties
Q20 | The second law of thermodynamicsdefines
- a) heat
- b) enthalpy
- c) internal energy
- d) entropy
Q21 | Which law of thermodynamics definesentropy
- a) first
- b) second
- c) third
- d) zeroeth
Q22 | Which of the following processes is essentially irreversible
- a) isothermal
- b) adiabatic
- c) isentropic
- d) thrittling
Q23 | A thermodynamic cycle operates between 400 K. & 290 K. 500 MJ/s of heat is added to the working substance.The power generated is
- a) 290 mw
- b) 290 mj
- c) 137.5 mw
- d) 137.5 mj
Q24 | A reversible engine performing as engine has efficiency of 62.5%. If it is reversed to work as refrigerator its COP will be
- a) 60%
- b) 62.5%
- c) 65%
- d) 37.5%
Q25 | A reversible engine performing as refrigerator has COP=33%. If the same machine operates as engine, its efficiencywill be
- a) 67%
- b) 33%
- c) 75%
- d) 37.5%