Chapter 1 - Thermodynamics Past Board Questions PDF

# Chapter 1 - Thermodynamics ## Past Board Questions 1. Enthalpy of an ideal gas is a function only of: - **A**. Entropy - **B**. Internal Energy - **C**. Temperature - **D**. Pressure **Answer: C** 2. Which of the following is the most efficient thermodynamic cycle? - **A*...

# Chapter 1 - Thermodynamics ## Past Board Questions 1. Enthalpy of an ideal gas is a function only of: - **A**. Entropy - **B**. Internal Energy - **C**. Temperature - **D**. Pressure **Answer: C** 2. Which of the following is the most efficient thermodynamic cycle? - **A**. Brayton - **B**. Otto - **C**. Carnot - **D**. Diesel **Answer: C** 3. What is the first law of thermodynamics? - **A**. Internal energy is due to molecular motions - **B**. Entropy of the universe is increased by irreversible processes - **C**. Energy can neither be created nor destroyed - **D**. Heat energy cannot be completely transformed into work **Answer: C** 4. An ideal gas is compressed isothermally. What is the enthalpy change? - **A**. Always negative - **B**. Always positive - **C**. Zero - **D**. Undefined **Answer: C** 5. What is the name of the process that has no heat transfer? - **A**. Isothermal - **B**. Isobaric - **C**. Polytropic - **D**. Adiabatic **Answer: D** 6. An ideal gas is compressed in a cylinder so well insulated that there is essentially no heat transfer. The temperature of the gas: - **A**. Decreases - **B**. Increases - **C**. Remains constant - **D**. Is zero **Answer: B** 7. What is the SI unit of pressure? - **A**. kg/sq cm - **B**. dynes/sq cm - **C**. Pascal - **D**. Psi **Answer: C** 8. The equation Cp = Cv + R applies to which of the following? - **A**. Enthalpy - **B**. Ideal gas - **C**. Two phase states - **D**. All pure substances **Answer: B** 9. In the flow process, neglecting kinetic and potential energies, the integral of Vdp represents what? - **A**. Heat transfer - **B**. Flow energy - **C**. Enthalpy change - **D**. Shaft work **Answer: D** 10. It is the mechanical energy of pressure that is transformed into energy of heat. - **A**. Kinetic energy - **B**. Enthalpy - **C**. Heat exchanger - **D**. Heat of compression **Answer: B** 11. If Joule Thompson coefficient is equal to zero, then the process will become: - **A**. Isentropic - **B**. Isobaric - **C**. Isenthalpic - **D**. Isothermal **Answer: D** 12. If the fluid will pass through a nozzle, then its entropy will: - **A**. Increase - **B**. Remain the same - **C**. Decrease - **D**. Become infinite **Answer: B** 13. Which of the following converts fossil fuels into shaft work? - **A**. Nuclear power plant - **B**. Gas turbine power plant - **C**. Dendrothermal power plant - **D**. Thermal power plant **Answer: D** 14. Dissolve gases like _______ will make water corrosive and react with metal to form iron oxide. - **A**. O2 and N2 - **B**. O2 and CO - **C**. O2 and CO2 - **D**. N2 and SO2 **Answer: C** 15. What is the critical temperature of mercury? - **A**. 1160 °C - **B**. 1260 °C - **C**. 1360 °C - **D**. 1460 °C **Answer: D** 16. What is the critical pressure of mercury? - **A**. 100 Mpa - **B**. 108 Mpa - **C**. 128 Mpa - **D**. 158 Mpa **Answer: B** 17. What is the method used in converting heat directly to electricity by magnetism? - **A**. Electromagnetic induction - **B**. Magnetodynamic - **C**. Magnetohydrodynamic - **D**. Thermoelectric **Answer: C** 18. Which of the following is NOT a material used for thermoelectric elements? - **A**. Bismuth telluride - **B**. Lead telluride - **C**. Zinc telluride - **D**. Germanium **Answer: C** 19. The law which states that "when a conductor and a magnetic field move relatively to each other, an electric voltage is induced in the conductor". - **A**. Maxwell's law - **B**. Kirchoff's law - **C**. Faraday's law - **D**. Voltage's law **Answer: C** 20. It is a device that transfers heat directly to electrical energy by utilizing thermionic emissions - **A**. Thermionic cell - **B**. Thermionic generator - **C**. Thermionic converter - **D**. Thermionic motor **Answer: B** 21. The theory of changing heat into mechanical work. - **A**. Thermodynamics - **B**. Kinematics - **C**. Inertia - **D**. Kinetics **Answer: A** 22. Average pressure on a surface when a changing pressure condition exist. - **A**. Back pressure - **B**. Partial pressure - **C**. Pressure drop - **D**. Mean effective pressure **Answer: D** 23. Which of the following cycles consists two isothermal and two constant volume processes? - **A**. Diesel cycle - **B**. Ericsson cycle - **C**. Stirling cycle - **D**. Otto cycle **Answer: C** 24. A control volume refers to what? - **A**. A fixed region in space - **B**. A reversible process - **C**. An isolated system - **D**. A specified mass **Answer: A** 25. In the polytropic process, PV^n = Constant, which of the following is the process if the value of n is infinitely large? - **A**. Isobaric - **B**. Isometric - **C**. Isothermal - **D**. Polytropic **Answer: B** 26. If the temperature is held constant and the pressure is increased beyond the saturation pressure, then the working medium must be: - **A**. Compressed liquid - **B**. Subcooled liquid - **C**. Saturated vapor - **D**. Saturated liquid **Answer: A** 27. Is one whose temperature is below the saturation temperature corresponding to its pressure. - **Α**. Superheated vapor - **B**. Wet vapor - **C**. Subcooled liquid - **D**. Saturated liquid **Answer: C** 28. Number of molecules in a mole of any substance is a constant called - **A**. Rankine constant - **B**. Avogadro's number - **C**. Otto constant - **D**. Thompson constant 29. If the pressure of a gas is constant the volume is directly proportional to the absolute temperature. - **A**. Boyle's law - **B**. Joule's law - **C**. Charles' law - **D**. Kelvin's law **Answer: C** 30. The number of protons in the nucleus of an atom or the number of electrons in the orbit of an atom. - **A**. Atomic volume - **B**. Atomic number - **C**. Atomic weight - **D**. Atomic mass **Answer: B** 31. Heat exchangers typically involve: - **A**. No work interactions - **B**. No heat interactions - **C**. No energy interactions - **D**. None of these **Answer: A** 32. What device is used to convert the heat to work? - **A**. Adiabatier - **B**. Regenerator - **C**. Heat engines - **D**. Generator **Answer: C** 33. The objective of a heat pump is to maintain a heated space at: - **A**. Low temperature - **B**. High temperature - **C**. Medium temperature - **D**. None of these **Answer: B** 34. What device that violates the second law of thermodynamics? - **A**. Perpetual motion machine of second kind - **B**. Perpetual motion machine of third kind - **C**. Perpetual-motion machine of the first kind - **D**. None of these **Answer: A** 35. How do you call the process if no irreversibilities that occur outside the system boundaries? - **A**. Externally reversible - **B**. Internally reversible - **C**. Reversible - **D**. None of these **Answer: A** 36. It is an energy interaction that is not accompanied by entropy transfer. - **A**. Energy interchange - **B**. Heat - **C**. Work - **D**. None of these **Answer: C** 37. ______ is used in aircraft engines and some automotive engine. In this method, a turbine driven by the exhaust gases is used to provide power to compressor or blower at the inlet. - **A**. Discharging - **B**. Turbocharging - **C**. Supercharging - **D**. Scavenging **Answer: B** 38. The only devices where the changes in kinetic energy are significant. - **A**. Compressor - **B**. Nozzles and diffusers - **C**. Pumps - **D**. None of these **Answer: B** 39. This is the device used to transfer heat from low temperature medium to a high temperature. - **A**. Adiabatic - **B**. Refrigerator - **C**. Heat exchanger - **D**. Heat pump **Answer: D** 40. In a P-T diagram of a pure substance, the curve separating the solid phase from the liquid phase is: - **A**. Vaporization curve - **B**. Fusion curve - **C**. Boiling point - **D**. Sublimation point **Answer: B** 41. The latent heat of vaporization for water in Joules per kg is equal to: - **A**. 5.4 x 10^2 - **B**. 4.13 x 10^3 - **C**. 22.6 x 10^5 - **D**. 3.35 x 10^5 **Answer: C** 42. Form of energy associated with the kinetic energy of the random motion of a large number of molecules. - **A**. Internal energy - **B**. Kinetic energy - **C**. Heat of fusion - **D**. Heat **Answer: D** 43. If the temperature is held constant and the pressure is increased beyond the saturation pressure, then the working medium must be: - **A**. Saturated vapor - **B**. Compressed liquid - **C**. Saturated liquid - **D**. Subcooled liquid **Answer: B** 44. Is the condition of pressure and temperature at which a liquid and its vapor are indistinguishable. - **A**. Critical point - **B**. Dew point - **C**. Absolute humidity - **D**. Relative humidity **Answer: A** 45. When a substance in gaseous state is below the critical temperature, it is called - **A**. Vapor - **B**. Moisture - **C**. Cloud - **D**. Steam **Answer: A** 46. Superheated vapor behaves: - **A**. Just as gas - **B**. Just as steam - **C**. Just as ordinary vapor - **D**. Approximately as a gas **Answer: D** 47. Which of the following provides the basis for measuring thermodynamic property of temperature? - **A**. Zeroth law of thermodynamics - **B**. First law of thermodynamics - **C**. Second law of thermodynamics - **D**. Third law of thermodynamics **Answer: A** 48. Mechanism designed to lower the temperature of air passing through it. - **A**. Air cooler - **B**. Air defense - **C**. Air spill over - **D**. Air cycle **Answer: A** 49. Heat normally flowing from a high temperature body to a low temperature body wherein it is impossible to convert heat without other effects. - **A**. First law of thermodynamics