# Phase Transformation MCQ Mechanical Engineering

50 Questions 30 Mins

Following are some of the multiple choice questions on the Phase Transformation with answers that will help the students in developing their knowledge.

## Phase Transformation MCQ

• mass
• temperature
• permission
• energy

### 2. Identify the correct order for the voltage transformation for the three-phase transformers.

• D-Y > D-D = Y-Y > Y-D
• D-Y > D-D > Y-Y > Y-D
• D-Y > D-D = Y-Y < Y-D
• D-Y > D-D < Y-Y < Y-D

• 73%
• 57%
• 173%
• 157%

• 73%
• 57%
• 173%
• 157%

• 120°, 90°
• 180°, 90°
• 120, 120°
• 120°, 180°

### 6. Operating transformers in parallel gives the advantage of ___________

• increased capacity of power system
• reducing the capacity of substation
• all of the mentioned

### 7. Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal and xa > xb. Then?

• A has poorer pf than B
• B has poorer pf than B
• lesser power factor angle
• both operate at same power factor

### 8. Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal. Then total kVA output of the output will be ___________

• less than sum of kVA of A and B
• more than sum of kVA of A and B
• equal to sum of kVA of A and B
• any of the mentioned

• A, B, C
• C
• A, B
• B, C

### 10. Which if the conditions is must be fulfilled for satisfactory parallel operation of transformers?

• Same voltage ratio
• Leakage impedances should be inversely proportional to kVA of the transformer
• Same pu impedance
• Correct polarity

• 1230 kVA
• 1440 kVA
• 1680 kVA
• 1150 kVA

### 12. Transformer operating in parallel will share a common load in the best possible manner if ____________

• leakage impedances are proportional to their kVA rating
• pu leakage impedances are equal
• leakage impedances are equal
• any of the mentioned

• freezing
• melting
• boiling
• condensation

• Sublimation
• Condensation
• Liquid
• deposition

• condensation
• evaporation
• expansion
• movement

• fusion
• Freezing
• sublimation
• evaporation

### 17. What is deposition?

• Phase change from gas to solid
• phase change from liquid to solid
• Phase change from solid to gas
• Phase change from liquid to gas

• expansion
• evaporation
• condensation
• sublimation

### 19. During a phase change what happens to temperature?

• it increases
• it decreases
• depends; if being heated it increases, if being cooled it decreases
• stays constant

### 20. What is sublimation?

• phase change between solid and liquid
• pahse change from gas to solid
• phase change from solid to gas
• phase change from solid to solid

### 21. Boiling is ...

• liquid to gas
• gas to solid
• gas to liquid
• solid to liquid

• Sublimation
• Deposition
• Fusion
• condensation

### 23. Melting is ...

• liquid to solid
• solid to liquid
• solid to gas
• gas to liquid

• Endothermic
• Exothermic
• Isothermal

### 25. If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero.

• Enthalpy
• Volume
• Both A & B
• Neither A nor B

### 26. Henry's law is closely obeyed by a gas, when its __________ is extremely high.

• Pressure
• Solubility
• Temperature
• None of these

• -273
• 0
• -78
• 5

### 28. The equation relating E, P, V and T which is true for all substanes under all conditions is given by (∂E/∂V)T = T.(∂P/∂T)H - P . This equation is called the

• Maxwell
• Thermodynamic equation of state
• Equation of state
• Redlich-Kwong equation of state

### 29. Which of the following is a shortcoming for using parallel connected transformers?I. Reliable loadingII. Increased capacity of power systemIII. Reducing the capacity of substation

• I, II, III
• I, II
• I, III
• None of the mentioned