Corrosion Technician Exam Study Guide PDF
2026/2027 | Corrosion Control, Inspection &
Certification Review
Practice Questions: Corrosion Fundamentals
1. What is the basic principle of corrosion of iron in water?
A) Oxidation (loss of electrons) at the anode only
B) Reduction (gain of electrons) at the cathode only
C) Both oxidation at the anode and reduction at the cathode
D) Neither oxidation nor reduction
Correct Answer: C
Corrosion is an electrochemical process requiring both anodic (oxidation) and
cathodic (reduction) reactions. Iron dissolves at the anode, and electrons are
consumed at the cathode (e.g., by oxygen reduction or hydrogen evolution). Both
half-reactions must occur for corrosion to proceed .
2. In a galvanic corrosion cell, electrons flow from the _____ to the _____
through the metallic path.
A) cathode; anode
B) anode; cathode
C) anode; electrolyte
D) cathode; electrolyte
Correct Answer: B
Electrons are produced at the anode (where oxidation occurs) and travel through
the metallic path to the cathode. The direction of electron flow is opposite to
,conventional current (which flows from cathode to anode). This is a fundamental
concept for understanding corrosion cells .
3. Which of the following are essential components of a corrosion cell?
A) Anode and cathode only
B) Anode, cathode, and electrolyte only
C) Anode, cathode, metallic path, and electrolyte
D) Electrolyte and metallic path only
Correct Answer: C
A complete electrochemical corrosion cell requires four components: anode (site of
oxidation), cathode (site of reduction), a metallic path (electrical connection), and
an electrolyte (ionic conductor). Without any of these, the corrosion process
cannot proceed .
4. According to Ohm's Law, if the resistance in a cathodic protection circuit
increases while voltage remains constant, what happens to current?
A) Current increases
B) Current decreases
C) Current remains unchanged
D) Current alternates direction
Correct Answer: B
Ohm's Law states I = V/R. With constant voltage, current is inversely proportional
to resistance. Increasing resistance reduces current flow. This is why high soil
resistivity reduces the effectiveness of cathodic protection systems .
5. What is the approximate open-circuit potential of a magnesium anode versus
a steel structure in typical soil?
, A) 0.1 V
B) 0.4 – 0.6 V
C) 1.0 – 1.5 V
D) 2.0 V
Correct Answer: B
Magnesium has a potential of approximately –1.55 V (vs. Cu/CuSO₄), while steel
has a potential of approximately –0.85 V. The difference is about 0.7 V under ideal
conditions. However, under practical load conditions, the driving voltage is
typically 0.4–0.6 V .
6. A carbon steel pipeline is experiencing corrosion in moist soil. Which of the
following represents the anodic reaction?
A) Fe → Fe²⁺ + 2e⁻
B) O₂ + 2H₂O + 4e⁻ → 4OH⁻
C) 2H⁺ + 2e⁻ → H₂
D) Fe²⁺ + 2e⁻ → Fe
Correct Answer: A
The anodic reaction is the oxidation of metal, where iron atoms lose electrons to
form ferrous ions. This dissolution of metal is what we observe as corrosion.
Options B and C are cathodic reactions (reduction). Option D would be plating, not
corrosion .
7. What does the term "Passivation" refer to in corrosion engineering?
A) Complete removal of all corrosion
B) Formation of a protective oxide film on a metal surface
C) The process of coating a metal with paint
D) Electrical isolation of a structure
Correct Answer: B
2026/2027 | Corrosion Control, Inspection &
Certification Review
Practice Questions: Corrosion Fundamentals
1. What is the basic principle of corrosion of iron in water?
A) Oxidation (loss of electrons) at the anode only
B) Reduction (gain of electrons) at the cathode only
C) Both oxidation at the anode and reduction at the cathode
D) Neither oxidation nor reduction
Correct Answer: C
Corrosion is an electrochemical process requiring both anodic (oxidation) and
cathodic (reduction) reactions. Iron dissolves at the anode, and electrons are
consumed at the cathode (e.g., by oxygen reduction or hydrogen evolution). Both
half-reactions must occur for corrosion to proceed .
2. In a galvanic corrosion cell, electrons flow from the _____ to the _____
through the metallic path.
A) cathode; anode
B) anode; cathode
C) anode; electrolyte
D) cathode; electrolyte
Correct Answer: B
Electrons are produced at the anode (where oxidation occurs) and travel through
the metallic path to the cathode. The direction of electron flow is opposite to
,conventional current (which flows from cathode to anode). This is a fundamental
concept for understanding corrosion cells .
3. Which of the following are essential components of a corrosion cell?
A) Anode and cathode only
B) Anode, cathode, and electrolyte only
C) Anode, cathode, metallic path, and electrolyte
D) Electrolyte and metallic path only
Correct Answer: C
A complete electrochemical corrosion cell requires four components: anode (site of
oxidation), cathode (site of reduction), a metallic path (electrical connection), and
an electrolyte (ionic conductor). Without any of these, the corrosion process
cannot proceed .
4. According to Ohm's Law, if the resistance in a cathodic protection circuit
increases while voltage remains constant, what happens to current?
A) Current increases
B) Current decreases
C) Current remains unchanged
D) Current alternates direction
Correct Answer: B
Ohm's Law states I = V/R. With constant voltage, current is inversely proportional
to resistance. Increasing resistance reduces current flow. This is why high soil
resistivity reduces the effectiveness of cathodic protection systems .
5. What is the approximate open-circuit potential of a magnesium anode versus
a steel structure in typical soil?
, A) 0.1 V
B) 0.4 – 0.6 V
C) 1.0 – 1.5 V
D) 2.0 V
Correct Answer: B
Magnesium has a potential of approximately –1.55 V (vs. Cu/CuSO₄), while steel
has a potential of approximately –0.85 V. The difference is about 0.7 V under ideal
conditions. However, under practical load conditions, the driving voltage is
typically 0.4–0.6 V .
6. A carbon steel pipeline is experiencing corrosion in moist soil. Which of the
following represents the anodic reaction?
A) Fe → Fe²⁺ + 2e⁻
B) O₂ + 2H₂O + 4e⁻ → 4OH⁻
C) 2H⁺ + 2e⁻ → H₂
D) Fe²⁺ + 2e⁻ → Fe
Correct Answer: A
The anodic reaction is the oxidation of metal, where iron atoms lose electrons to
form ferrous ions. This dissolution of metal is what we observe as corrosion.
Options B and C are cathodic reactions (reduction). Option D would be plating, not
corrosion .
7. What does the term "Passivation" refer to in corrosion engineering?
A) Complete removal of all corrosion
B) Formation of a protective oxide film on a metal surface
C) The process of coating a metal with paint
D) Electrical isolation of a structure
Correct Answer: B
