mechanical engineering mcq for upcoming technical exam

Mechanical Engineering Model mcq for Upcoming Exam.

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01. In Rankine cycle, the work output from the turbine  is given by __________.

A. change of internal energy between inlet and outlet

B. change of enthalpy between inlet and outet

C. change of entropy between inlet and outlet

D. change of temperature between inlet and outlet

Correct Answer : B

02. If a reheater is added to a Rankine Cycle, then usually ___________.

A. the net work increases and dryness fraction at the exit of turbine increases.

B. the net work and efficiency decrease 

C. the net work remains same and efficiency increases 

D. the net work increases and efficiency remains same 

Correct Answer : A

Reheat Rankine Cycle is essentially a modification of simple Rankine cycle.

In reheating the dryness fraction of steam at the exit increases and also net work increases. 

The thermal efficiency may increase or may decrease depending upon the mean temperature of heat addition.

03. In an axial flow compressor, when the degree of reaction is 50%, it implies that 

A. Work done is compression will be the least 

B. 50% stages of the compressor will be ineffective 

C. Pressure after compression will be optimum 

D. The compressor will have symmetrical blades 

Correct Answer : D

04. Which type of compressor is commonly used in a gas turbine plant?

A. Reciprocating compressor

B. Screw compressor

C. Multistage axial flow compressor

D. Either (A) & (B)

Correct Answer : C

Multistage axial flow compressor is the compressor in practical usage in a gas turbine plant.

05. The psychrometric chart graphically represents

A. Interrelation of air temperature and moisture.

B. Interrelation of air pressure and moisture.

C. Interrelation of volume and temperature.

D. Interrelation of pressure and temperature.

Correct Answer : A

The atmosphere is a mixture of air (oxygen and nitrogen) and water vapour. Psychrometry is the study of moist air and of the changes in its conditions.

06. In psychrometric chart, which lines have highest slope?

A. WBT (wet bulb temp.)

B. h. (sp. Enthalpy)

C. Relative humidity

D. v (specific volume)

Correct Answer : D

In psychrometric chart, specific volume lines have highest slope.

07. In a psychrometric chart, relative humidity lines are: 

A. Curved 

B. Inclined and straight but non-uniformly spaced 

C. Horizontal and non-uniformly spaced 

D. Horizontal and uniformly spaced 

Correct Answer : A

In psychrometric chart, relative humidity (RH) lines are curved having positive slope from zero to infinite. 

08. Which of the following properties of refrigerant is not desirable?

A. Low boiling point

B. High critical temperature

C. Specific volume at the inlet of compressor must be high

D. Low Viscosity

Correct Answer : C

Work input to the compressor is directly dependent upon the volume at the inlet of compressor.

More the volume, more will be the work.

Thus, it is undesirable.

All others are desirable.

09. The Mollier diagram of a pure substance is a

A. h-s diagram

B. T-s diagram

C. P-h diagram

D. h-P diagram

Correct Answer : A

The Mollier diagram of a pure substance is enthalpy(h) vs. entropy(s) diagram.

So, the correct option is (a).

10. The cutting force in punching and blanking operations mainly depends on

A. the modulus of elasticity of metal.

B. the shear strength of metal

C. the bulk modulus of metal

D. the yield strength of metal

Correct Answer : B.