Thermodynamics Set 8

Mechanical Engineering

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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on Thermodynamics Set 8

Q1 | The specific heat at constant volume of solids obeys Deby's T3 law
  • at low pressures
  • at low temperatures
  • at high pressures
  • at all temperatures
  • Pulsejet
Answer: at all temperatures
Q2 | The temperature, in degrees celsius, at which the colsius scale reading is numerically half the Fahrenheit scale reading is
  • 80?C
  • Pulsejet
  • 42?C
  • 160?C
  • 20?C
Answer: 160?C
Q3 | A jar contains a mixture of oxygen and hydrogen gas in the ratio 1 : 5. The ratio of mean knetic energies of hydrogen and oxygen molecules is
  • Pulsejet
  • 1 ; 4
  • 1 ; 1
  • 1 ; 16
  • 1 ; 5
Answer: 1 ; 1
Q4 | For any irreversible process the net entropy change is
  • Zero
  • Negative
  • Positive
  • Infinite
  • Unity
Answer: Positive
Q5 | Heat can flow from cold substance to hot substance with the aid of external work". Which of the following name is associated with the above statement?
  • Gay Lussac
  • Clausius
  • Planck
  • Kelvin
  • Joule
Answer: Clausius
Q6 | In which case the work done per kg of air compressed from 1.05 ata, 15?C to 6.3 ata is minimum
  • Polytropic pv1.4 = C
  • Adiabatic
  • Isothermal
  • Polytropic pv1.3 = C
  • Polytropic pv1.35 = C
Answer: Isothermal
Q7 | The statement that molecular weight of all gases occupy the same volume at NTP is known as
  • Dalton's law
  • Avogadro's hypothesis
  • Joule's law
  • First law of thermodynamics
  • Charle's law
Answer: Avogadro's hypothesis
Q8 | 1 atmospheric pressure is equal to
  • 1.1 kg/cm2
  • 1.033 kg/cm2
  • 14.7 kg/cm2
  • 1 kg/cm2
  • 1.133 kg/cm2
Answer: 1.033 kg/cm2
Q9 | The relation of the vapour pressure to the enthalpy of vaporization is expressed in
  • Clausius Clapeyron equation
  • Gas equation
  • Energy equation
  • Maxwell's equation
  • Van der Waal's equation
Answer: Clausius Clapeyron equation
Q10 | During throttling process
  • Pressure does not change
  • Entropy does not change
  • Enthalpy does not change
  • Internal energy does not change
  • Volume change is negligible
Answer: Enthalpy does not change
Q11 | Which of the following is an extensive property?
  • Pulsejet
  • Viscosity
  • Surface tension
  • Refractive index
  • Heat capacity
Answer: Heat capacity
Q12 | The charge in a Diesel engine consists of
  • Air + diesel + lubricating oil
  • Diesel + lubricating oil
  • Air + lubricating oil
  • Air
  • Air + diesel
Answer: Air
Q13 | Which of the following is incorrect?
  • The pressure of a mixture of gases is equal to the sum of the pressure of the individual components taken each at the temperature and volume of the mixture
  • The entropy of a mixture of gases is equal to the sum of the entropies of the individual components taken each at the temperature and volume of the mixture
  • The internal energy of a mixture of gases is equal to the sum f the internal energies of the indicudual components taken each at the temperature and the volume of the mixture
  • (B) and (C) above
  • None of the above
Answer: None of the above
Q14 | One kg of water is evaporated from 6 kg of sea water containing 4% salt. The percentage of salt in the remaining solution will be
  • 4%
  • 6%
  • 3.33%
  • 4.80%
  • 1%
Answer: 4.80%
Q15 | In case of real gases, Cp will be equal to Cv
  • Pulsejet
  • at triple point
  • at absolute zero
  • above critical temperature
  • at critical temperature
Answer: at absolute zero
Q16 | If a surface is elastically hit by N balls each of mass M, moving with same velocity V, the force on the surface will be
  • 2 MNV2
  • MNV
  • Pulsejet
  • 2 MNV
  • 4 MNV
Answer: 2 MNV
Q17 | Antifreeze chemicals are
  • Those which lower down the freezing points of liquids
  • Those which do not freeze at all
  • Always in liquid state even at low temperatures
  • Those which are added to refrigerants for better performance
  • Same as refrigerants
Answer: Those which lower down the freezing points of liquids
Q18 | A carburettor is used to supply
  • Air + lubricating oil
  • Petrol + air
  • Petrol + lubricating oil
  • Petrol + air + lubricating oil
  • Diesel + air + lubricating oil
Answer: Petrol + air
Q19 | In an adiabatic compression the decrease in volume is associated with
  • Decrease in temperature and increase in pressure
  • Decrease in temperature and decrease in pressure
  • Increase in temperature and decrease in temperature
  • Increase in temperature and increase in pressure
  • None of the above
Answer: Increase in temperature and increase in pressure
Q20 | A gas having adiabatic index y = 1.4 and atmic weight A will have molecular weight
  • A
  • 2A
  • Pulsejet
  • 3A
Answer: 2A
Q21 | Identify the incorrect statement
  • The temperature scale is independent of the properties of any substance
  • The size of a unit of temperature, the degree, has a rational interpretation
  • A region of coldest temperature, an absolute zero, is well defined
  • All of the above
  • None of the above
Answer: None of the above
Q22 | When a bicycle pump is operated slowly the process of compression will be nearly
  • Throttling process
  • Isothermal process
  • Free compression
  • Constant volume process
  • Constant pressure process
Answer: Isothermal process
Q23 | For water, boiling and melting point will concide at
  • 100? K
  • 216.73? K
  • 200? K
  • 2730.16? K
  • 0? K
Answer: 2730.16? K
Q24 | 1 bar pressure is nearly equal to
  • 13.4 mm Hg
  • 1 mm Hg
  • 100 mm Hg
  • 750 mm Hg
  • 735 mm Hg
Answer: 750 mm Hg
Q25 | In a Carnot cycle the process which must be carried out at extremely slow speed is
  • adiabatic compression
  • adiabatic expansion
  • isothermal compression
  • None of the above
  • Pulsejet
Answer: isothermal compression
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