Engineering thermodynamics mcq part 1

Engineering thermodynamics mcq part 1

01. The sum of internal energy (U) and the product of pressure and volume (p. v) is known as

A.    enthalpy

Explanations: - enthalpy is a thermodynamic quantity equivalent to the total heat content of a system. The enthalpy of a homogeneous system is defined as

H=U+pV

02. The value of 1 mm of Hg is equal to

A .133.3 N/m2

Explanations: - A millimeter of mercury is a manometric unit of pressure. It is denoted by the symbol "mmHg".

03. One kg of carbon requires 4/3 kg of oxygen and produces 7/3 kg of

A. carbon monoxide gas.

04. Which of the following is the lightest and most volatile liquid fuel?

A. Gasoline

Explanations: -  Gasoline (American English) or petrol (British English), is a transparent, petroleum-derived liquid that is used primarily as a fuel in internal combustion engines.

05. The processes occurring in open system which permit the transfer of mass to and from the system, are known as

A. flow processes

06. Work done in a free expansion process is

A. zero

07. Which of the following has the minimum atomic mass?

A. Carbon

Explanations: -  1 atomic mass unit is defined as 1/12 of the mass of a single carbon-12 atom.

08. The efficiency of Diesel cycle approaches to Otto cycle efficiency when

A. cut-off is zero

09. The entropy increases in an

A. irreversible cyclic process.

10. The atomic mass of oxygen is

A .16

11. The ratio of specific heat at constant pressure (cp) and specific heat at constant volume (cv) is

A .Greater than one

12. The efficiency of Stirling cycle is equal to

A. Carnot cycle.

13. There is no change in internal energy in an

A. isothermal process.

Note: - An isothermal process is a change of a system, in which the temperature remains constant: ΔT = 0.

14. If the value of n = 0 in the equation pvⁿ = C, then the process is called

A. constant pressure process

Note:- An isobaric process is a thermodynamic process in which the pressure stays constant: ΔP = 0.

15. When coal is strongly heated continuously for 42 to 48 hours in the absence of air in a closed vessel, the process is known as

A .carbonisation of fuel.

16. Which of the following is correct?

A.Absolute pressure = Gauge pressure + Atmospheric pressure

17. Which of the following gas is mostly used in town for street and domestic lighting and heating?

A. Coal gas

18. The value of gas constant (R) in S. I. units is

A . 287 J/kgK

19. In the first law of thermodynamics, the

A. total energy of the system remains constant.

Note: - The first law of thermodynamics is a version of the law of conservation of energy

20. The efficiency of Diesel cycle increases with

A. decrease in cut-off

21. The kinetic energy of molecules of a gas becomes zero at

A. absolute zero temperature.

Explanations: - physically impossible-to-reach temperature of zero kelvin, or minus 459.67 degrees Fahrenheit (minus 273.15 degrees Celsius), atoms would stop moving.

22. One kg of carbon monoxide requires 4/7  kg of oxygen to produce

A. 11/7 kg of carbon dioxide gas.

23. The absolute zero temperature is taken as

A.-273°C

Note: - Absolute zero, temperature at which a thermodynamic system has the lowest energy. It matches to −273.15 °C on the Celsius temperature scale and to −459.67 °F on the Fahrenheit temperature scale.

24. The specific heat of water is

A .4.187

25. The constant pressure, constant volume and constant pvⁿprocesses are regarded as

A. irreversible process.

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