Phase Transformation MCQ Mechanical Engineering

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About Phase Transformation

Phase transformation is an amazing process that can take a solid material and turn it into a liquid. It's hard to believe that something as sturdy as a metal can be turned into something so malleable, but phase transformations are responsible for everything from the steel in your car to the water you drink.

Let's take a closer look at how phase transformations work

When a phase transformation occurs, the atoms in the solid material rearrange themselves into a new structure. This process is called phase change, and it usually happens when the material is heated or cooled. The temperature at which a phase change occurs is called the melting point or freezing point.

Phase changes are responsible for some of the most important properties of materials. For example, metals are strong because their atoms are tightly bonded together in a solid structure. But when metal is heated, its atoms become less bonded and can flow more easily, which is why liquid metal is so useful for making shapes.

Phase transformations are also responsible for the way water behaves. Water is a liquid at room temperature, but it can turn into a solid (ice) or a gas (steam) when it's heated or cooled.

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

1. All changes in the state of matter of a substance requires a change in

  • 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

3. For a star-delta three phase transformer, if the transformation ratio is ‘x:1’, then how much percent of output will be?

  • 73%
  • 57%
  • 173%
  • 157%

4. For a delta-star three phase transformer, if the transformation ratio is ‘x:1’, then how much percent of output will be improved?

  • 73%
  • 57%
  • 173%
  • 157%

5. In three phase supply, the voltage phases are displaced by ________ and in two phase by ___________

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

6. Operating transformers in parallel gives the advantage of ___________

  • reliable loading
  • 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

9. Which of the following is the correct matching made for the harmonics and the associated harmonic component?A. Positive sequence components - 5th harmonic componentB. Negative sequence components - 7th harmonic componentC. Zero sequence components - 3rd harmonic component

  • 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

11. A 2000/1000/500 three winding transformer is to be used as auto transformer with supply of 3000 V. Two loads of 1050 kVA at 3500V and other one at 180 kVA at 1000V. The total kVA supplied will be?

  • 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

13. What is the phase change of a solid to a liquid?

  • freezing
  • melting
  • boiling
  • condensation

14. What is it called when a solid turns directly into a gas?

  • Sublimation
  • Condensation
  • Liquid
  • deposition

15. Change from gas to liquid...

  • condensation
  • evaporation
  • expansion
  • movement

16. Change from Liquid to Solid is call......

  • 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

18. Change from liquid to gas is called....

  • 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

22. Change from Gas to Solid is called........

  • Sublimation
  • Deposition
  • Fusion
  • condensation

23. Melting is ...

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

24. The ammonia synthesis reaction represented by N₂ + 3H₂ ⇋ 2NH₃ ; ΔH = - 22.4 kcal, is

  • Endothermic
  • Exothermic
  • Isothermal
  • Adiabatic

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

27. Sublimation temperature of dry ice (solid CO₂) is __________ °C.

  • -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

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