Engineering thermodynamics mcq part 3

Engineering thermodynamics mcq part 3

1. The compression ratio for Diesel

engines are.

15 to 20.

2. In an isothermal process,

there is no change in temperature.

there is no change in enthalpy.

there is no change in internal energy.

So answer is all of these.

Explanation: -

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

3. The efficiency of a dual combustion cycle depends upon.

cut-off ratio.

4. Which of the following gas has a minimum molecular mass?

Hydrogen.

5. The value of cp/cv for air is.

1.4.

6. One Joule (J) is equal to.

1 N-m.

7. When the expansion or compression takes place according to the law pvⁿ = C, the process is known as.

polytropic process.

Explanation: -

where p is the pressure, v is specific volume, n is the polytropic index (a real number), and C is a constant.

8. The entropy is a point function and thus.

it is a property of the same.

Explanation: -

Entropy may be understood as a measure of disorder within a macroscopic system.

9. The state of a substance whose evaporation from its liquid state is complete, is known as.

perfect gas.

Explanation: -

Understand the perfect gas

In physics, a perfect gas is a theoretical gas that differs from real gases in a way that makes certain calculations easier to handle. Its behavior is more simplified compared to an ideal gas (also a theoretical gas).

10. An open cycle gas turbine works on.

Joule's cycle.

Explanation: -

joule cycle consists of two constant pressure and two reversible adiabatic or isentropic processes.

11. The efficiency of Carnot cycle depends upon.

temperature limits.

12. The gas turbine cycle with regenerator improves.

thermal efficiency.

13. Which of the following has the highest calorific value?

Anthracite coal.

14. When a gas is heated, change takes place in.

Pressure.

Volume.

Temperature.

all of these.

15. Which of the following is an intensive property of a thermodynamic system?

Temperature.

Explanation: -

examples of intensive properties are

color, boiling point, pressure, molecular weight and density.

Remember that density is mass divided by volume.

And remember, both mass and volume are extensive properties, or dependent on the amount of matter.

16. The heat and mechanical energies are mutually convertible. This statement was established by.

Joule.

17. In an isolated system, neither the heat and work nor the, mass of the working substance crosses the boundary of the system.

18. The hard coke is obtained when carbonisation of coal is carried out at.

900° to 1100°C.

19. According to First law of thermodynamics,

total energy of a system remains constant.

20. The ratio of molar specific heats for monoatomic gas is

1.67.

21. The value of universal gas constant is.

 same for all gases.

Explanation: -

The gas constant R value is 8.314 J / mol. K.

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