Corrosion Engineering – MCQs – Practices Test .com

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1. Corrosion is best defined as:
(A) Mechanical wear of metals
(B) Degradation of materials by chemical or electrochemical reaction with the environment
(C) Surface polishing of metals
(D) Deformation of metals under stress

2. The most common form of corrosion in metals is:
(A) Galvanic corrosion
(B) Uniform corrosion
(C) Pitting corrosion
(D) Stress corrosion cracking

3. In a galvanic cell, corrosion occurs at the:
(A) Cathode
(B) Anode
(C) Both electrodes equally
(D) Neither electrode

4. The driving force for corrosion reactions is:
(A) Temperature gradient
(B) Pressure difference
(C) Difference in electrode potential
(D) Mechanical load

5. Which metal is the most corrosion-resistant under normal conditions?
(A) Zinc
(B) Iron
(C) Platinum
(D) Copper

6. Pitting corrosion is most dangerous because:
(A) It occurs uniformly
(B) It is easily visible
(C) It causes localized deep penetration
(D) It increases ductility

7. Galvanic corrosion occurs when:
(A) Two similar metals are exposed to dry air
(B) Two dissimilar metals are electrically connected in an electrolyte
(C) Metals are exposed to high temperature only
(D) A single metal corrodes in oxygen-free water

8. Which of the following is a protective coating method?
(A) Galvanizing
(B) Electroplating
(C) Painting
(D) All of the above

9. Stainless steel resists corrosion mainly due to:
(A) High nickel content
(B) Protective chromium oxide film
(C) High carbon content
(D) Polishing

10. Cathodic protection prevents corrosion by:
(A) Making the metal the anode
(B) Making the metal the cathode
(C) Applying paint
(D) Increasing temperature

11. Which is NOT a type of corrosion?
(A) Crevice corrosion
(B) Pitting corrosion
(C) Fatigue corrosion
(D) Welding corrosion

12. Crevice corrosion usually occurs in:
(A) Open surfaces exposed to oxygen
(B) Narrow gaps or shielded areas
(C) High-pressure pipelines
(D) Vacuum environments

13. The main electrolyte in seawater corrosion is:
(A) NaCl solution
(B) H2SO4
(C) Pure water
(D) CO2

14. Which corrosion form is caused by combined tensile stress and corrosive environment?
(A) Pitting
(B) Stress corrosion cracking (SCC)
(C) Uniform corrosion
(D) Galvanic corrosion

15. Dezincification is selective corrosion of:
(A) Brass
(B) Aluminum
(C) Stainless steel
(D) Titanium

16. The most widely used sacrificial anode material in pipelines is:
(A) Copper
(B) Zinc
(C) Platinum
(D) Iron

17. Intergranular corrosion occurs along:
(A) Crystal lattice planes
(B) Grain boundaries
(C) Metal surfaces
(D) Weld deposits only

18. Which factor increases the rate of corrosion?
(A) Low humidity
(B) High temperature
(C) Presence of salts
(D) Both (B) and (C)

19. Anodic inhibitors prevent corrosion by:
(A) Making the anode inactive
(B) Making the cathode inactive
(C) Coating the surface with oil
(D) Increasing current flow

20. Which test is commonly used to study corrosion rates?
(A) Tensile test
(B) Salt spray test
(C) Charpy test
(D) Impact test

21. The corrosion of iron in moist air is accelerated by:
(A) Presence of CO2
(B) Presence of SO2
(C) Presence of salts
(D) All of the above

22. The potential difference between two dissimilar metals in a galvanic series is measured in:
(A) Volts
(B) Amperes
(C) Ohms
(D) Coulombs

23. The corrosion rate is usually expressed in:
(A) mm/year
(B) N/m²
(C) kJ/mol
(D) W/m²

24. The Nernst equation is used to calculate:
(A) Corrosion penetration rate
(B) Electrode potential
(C) Stress-strain behavior
(D) Heat transfer rate

25. Corrosion fatigue occurs due to:
(A) Alternating stress in corrosive environment
(B) Static loading
(C) High temperature only
(D) Vacuum conditions

26. Which of these metals forms a passive film naturally?
(A) Aluminum
(B) Titanium
(C) Chromium
(D) All of the above

27. The main difference between cathodic and anodic protection is:
(A) Cathodic makes the structure a cathode, anodic maintains it in passive state
(B) Cathodic is temporary, anodic is permanent
(C) Cathodic uses inhibitors, anodic uses coatings
(D) Both are identical methods

28. Uniform corrosion is also called:
(A) Localized corrosion
(B) General corrosion
(C) Selective corrosion
(D) Crevice corrosion

29. Hydrogen embrittlement is caused by:
(A) Absorption of hydrogen atoms in metal
(B) Oxygen deposition on surface
(C) Excessive coating thickness
(D) High carbon content

30. The Pourbaix diagram shows:
(A) Stress-strain curve
(B) Stability of metals as a function of potential and pH
(C) Flow rate of fluids
(D) Temperature dependence of creep

31. Which corrosion is accelerated by differential aeration?
(A) Galvanic corrosion
(B) Crevice corrosion
(C) Uniform corrosion
(D) Stress corrosion

32. The galvanic series is established in:
(A) Dry air
(B) Seawater
(C) Hydrocarbons
(D) Hydrogen gas

33. Which is NOT a corrosion control method?
(A) Protective coatings
(B) Cathodic protection
(C) Alloy selection
(D) Increasing humidity

34. Corrosion inhibitors are commonly added to:
(A) Fuels
(B) Cooling water systems
(C) Lubricants
(D) All of the above

35. Erosion-corrosion occurs due to:
(A) Flow of corrosive fluid at high velocity
(B) High humidity
(C) Microbial growth
(D) Galvanic couple

36. Which bacteria are known to cause microbial corrosion?
(A) Sulfate-reducing bacteria (SRB)
(B) Iron-oxidizing bacteria
(C) Both (A) and (B)
(D) None

37. Which industry faces the most corrosion-related losses?
(A) Food processing
(B) Oil and gas
(C) Textile
(D) Paper

38. Passivation is the process of:
(A) Removing oxide film
(B) Formation of protective oxide film
(C) Coating with paint
(D) Heating metals

39. The cost of corrosion to global economy is approximately:
(A) 0.1% of GDP
(B) 1–2% of GDP
(C) 3–4% of GDP
(D) 10% of GDP

40. Which form of corrosion occurs under insulation materials?
(A) Crevice corrosion
(B) Stress corrosion
(C) Corrosion under insulation (CUI)
(D) Pitting

41. The polarization curve in corrosion studies represents:
(A) Potential vs. stress
(B) Potential vs. current density
(C) Temperature vs. time
(D) Velocity vs. pressure

42. Noble metals resist corrosion because:
(A) They form thick oxide layers
(B) They have high electrode potentials
(C) They are mechanically hard
(D) They have high density

43. The corrosion allowance in pipeline design is usually:
(A) 0.5–1 mm
(B) 1–3 mm
(C) 5–10 mm
(D) 10–20 mm

44. Galvanizing is coating steel with:
(A) Zinc
(B) Nickel
(C) Copper
(D) Chromium

45. The function of impressed current cathodic protection (ICCP) is:
(A) Use sacrificial anodes only
(B) Supply external current to protect structure
(C) Form passive oxide films
(D) Increase mechanical strength

46. Which material is highly resistant to corrosion in acidic environments?
(A) Carbon steel
(B) Stainless steel
(C) Titanium
(D) Zinc

47. Which form of corrosion is associated with weld areas?
(A) Intergranular corrosion
(B) Pitting corrosion
(C) Galvanic corrosion
(D) SCC

48. Localized corrosion that produces fine cracks in pipelines is called:
(A) Pitting
(B) SCC
(C) Fatigue
(D) Uniform corrosion

49. The main advantage of anodic protection is:
(A) Suitable for metals that can passivate
(B) Requires less monitoring than cathodic protection
(C) Works for all metals equally
(D) Cheaper than coatings

50. Corrosion engineering aims to:
(A) Eliminate corrosion completely
(B) Control and minimize corrosion to acceptable levels
(C) Increase corrosion for faster replacement
(D) Stop material production

Corrosion Engineering – MCQs

FOUNDATIONAL SUBJECTS (Year 1 – Year 2)

CORE PETROLEUM ENGINEERING SUBJECTS (Year 2 – Year 4)

LABORATORIES & PRACTICALS (Theory-based MCQs can be made from these)

ELECTIVES (Optional/Advanced)