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Question 1. Which type of electrochemical cell generates electrical energy through spontaneous chemical reactions? A) Galvanic cell B) Electrolytic cell C) Fuel cell D) Concentration cell Answer: A Explanation: Galvanic cells produce electrical energy spontaneously by converting chemical energy through oxidation-reduction reactions, unlike electrolytic cells which require external power to drive non-spontaneous reactions. Question 2. In an electrochemical cell, the electrode where oxidation occurs is called the: A) Cathode B) Anode C) Electrolyte D) Conductor Answer: B
Explanation: The anode is the electrode where oxidation (loss of electrons) takes place, whereas the cathode is where reduction occurs. Question 3. Which reaction describes the reduction process in a galvanic cell? A) Metal loses electrons B) Metal gains electrons C) Electrons are transferred from electrolyte to electrode D) Oxidation occurs at the cathode Answer: B Explanation: Reduction involves gaining electrons; in a galvanic cell, the cathode is where reduction occurs. Question 4. The standard electrode potential is measured relative to which reference electrode? A) Silver/Silver chloride electrode B) Standard Hydrogen Electrode (SHE) C) Calomel electrode
C) The complete absence of corrosion D) The metal's inability to conduct electricity Answer: B Explanation: Passivity involves the formation of a thin, stable oxide film on the metal surface, which inhibits further corrosion. Question 7. Uniform corrosion is characterized by: A) Localized pitting B) Even material loss over the surface C) Cracking along grain boundaries D) Rapid corrosion at crevices Answer: B Explanation: Uniform corrosion results in even material loss across the entire surface, unlike localized forms like pitting or crevice corrosion. Question 8. Galvanic corrosion severity increases with: A) Larger differences in electrode potentials
B) Similar potentials of paired metals C) Use of protective coatings D) Low soil resistivity only Answer: A Explanation: The greater the potential difference between two dissimilar metals, the more severe the galvanic corrosion due to higher driving voltage. Question 9. Pitting corrosion initiation often occurs at: A) Coating holidays B) Areas of uniform coating adhesion C) Areas with low chloride concentration D) Well-passivated regions Answer: A Explanation: Coating holidays are defects where the protective coating is absent, creating initiation points for pitting. Question 10. Critical pitting potential is defined as:
Question 12. Intergranular corrosion typically occurs due to: A) Excessive mechanical stress B) Sensitization of the alloy during heating C) Uniform oxidation D) Low environmental humidity Answer: B Explanation: Sensitization during heating causes chromium carbide precipitation at grain boundaries, leading to intergranular corrosion. Question 13. Dealloying, such as dezincification, involves: A) Loss of specific alloy components, weakening the metal B) Formation of protective oxide layers C) Uniform corrosion across the surface D) The complete dissolution of the metal Answer: A Explanation: Dealloying is selective corrosion where one component (like zinc) is leached out, compromising the alloy's integrity.
Question 14. Stress corrosion cracking (SCC) requires an environment that is: A) Chemically aggressive and under tensile stress B) Neutral and under compression C) Inert and static D) Rich in chlorides but without stress Answer: A Explanation: SCC occurs when tensile stress and a corrosive environment combine to cause crack initiation and propagation. Question 15. Hydrogen embrittlement in metals is primarily caused by: A) Hydrogen atoms diffusing into the metal under stress B) The formation of oxide films C) Galvanic interactions with cathodes D) Depletion of alloying elements Answer: A
Explanation: Coupons provide a direct method to quantify corrosion rates by measuring material loss over time. Question 18. Electrochemical techniques like polarization resistance are used to: A) Quantify corrosion rate B) Detect coating holidays C) Measure soil resistivity D) Determine coating adhesion strength Answer: A Explanation: Polarization resistance measurements correlate with corrosion rate, providing rapid assessment. Question 19. Non-destructive testing methods for corrosion detection include: A) Ultrasonic testing and eddy current B) Weight loss coupons C) Gravimetric analysis D) Tensile testing
Answer: A Explanation: Ultrasonic and eddy current testing are non- destructive techniques used to assess internal or surface defects related to corrosion. Question 20. Corrosion mapping involves: A) Spatially recording corrosion activity across a structure B) Measuring soil resistivity at one point C) Conducting chemical analysis of corrosion products D) Applying protective coatings Answer: A Explanation: Corrosion mapping visualizes and quantifies corrosion severity at different locations on a structure. Question 21. Adequate cathodic protection (CP) criteria are often defined as a potential of: A) −850 mV CSE B) 0 V CSE C) +150 mV CSE
C) Steel or iron D) Graphite and titanium Answer: A Explanation: Sacrificial anodes are active metals like magnesium, zinc, or aluminum that corrode preferentially to protect the structure. Question 24. A key limitation of magnesium sacrificial anodes is: A) Their high corrosion rate in high resistivity soils B) Their inability to provide sufficient current C) Their tendency to passivate quickly D) Their high cost compared to zinc Answer: A Explanation: Magnesium anodes are highly active but may have limited lifespan in high resistivity environments. Question 25. Impressed Current Cathodic Protection (ICCP) systems use:
A) External power sources like rectifiers B) Self-corroding metals only C) Only passive coatings D) Batteries exclusively Answer: A Explanation: ICCP systems rely on external DC power supplied by rectifiers to provide protective current. Question 26. A rectifier in an ICCP system is used to: A) Convert AC to DC power B) Increase soil resistivity C) Measure coating holidays D) Detect stray currents Answer: A Explanation: Rectifiers convert AC from the power supply into DC, which is necessary for cathodic protection.
Explanation: Proper design accounts for current density limits, voltage drops, and other electrical parameters to ensure effective protection. Question 29. Shielding effects in CP systems can be caused by: A) Nearby metallic structures or utilities B) Soil moisture content C) External light sources D) Coating adhesion strength Answer: A Explanation: Metallic structures or utilities can shield portions of the structure from CP current, reducing effectiveness. Question 30. Mitigation of shielding effects can include: A) Installing additional anodes or adjusting current output B) Removing protective coatings C) Increasing soil resistivity D) Decreasing anode size
Answer: A Explanation: Additional anodes or adjusting current can improve current distribution and overcome shielding. Question 31. To calculate the current requirement for a coated pipeline with holidays, one should consider: A) The total surface area minus holiday areas B) Only the total length of the pipeline C) The soil resistivity alone D) The color of the coating Answer: A Explanation: Holiday areas are uncoated, requiring additional current; total current needs to account for both coated and holiday areas. Question 32. Anode resistance in a groundbed can be calculated using: A) The formula R = ρ / (2π × length × diameter) B) Ohm’s law only
B) Maximize resistance C) Increase installation cost D) Reduce current flow Answer: A Explanation: Proper cable sizing reduces voltage drops and ensures the system functions efficiently. Question 35. The expected life of a galvanic anode can be estimated based on: A) The anode’s consumption rate and current output B) The soil temperature only C) The ambient humidity only D) The coating thickness only Answer: A Explanation: Anode life depends on the rate at which it corrodes and the current it supplies over time. Question 36. Fusion Bond Epoxy (FBE) coatings are favored because they:
A) Provide high adhesion and dielectric strength B) Are inexpensive and easily applied C) Are transparent and decorative D) Conduct electricity to enhance CP Answer: A Explanation: FBE coatings offer excellent adhesion, dielectric properties, and durability, making them suitable for CP. Question 37. Holiday detection in coatings involves: A) Using holiday detectors or holiday scanners B) Visual inspection only C) Magnetic resonance imaging D) Ultrasonic thickness gauging Answer: A Explanation: Holiday detectors identify defects (holidays) in coatings where corrosion might initiate. Question 38. Coating holidays impact CP by:
