AMPP NACE CORROSION TECHNOLOGIST
EXAM QUESTIONS AND VERIFIED
ANSWERS WITH RATIONALES
Question 1: Which of the following best describes the fundamental
electrochemical nature of most aqueous corrosion processes?
A. Purely chemical dissolution without electron transfer
B. Anodic metal oxidation coupled with cathodic reduction reactions involving
electron flow
C. Mechanical wear caused by fluid velocity alone
D. Thermal degradation of the metal lattice
CORRECT ANSWER: B. Anodic metal oxidation coupled with cathodic
reduction reactions involving electron flow
Rationale: Aqueous corrosion is an electrochemical process in which metal atoms at
anodic sites lose electrons (oxidation) while a reduction reaction occurs at cathodic
sites, completing the electrical circuit through the metal and the electrolyte.
Question 2: In a galvanic couple, which metal will preferentially corrode?
A. The metal with the more noble (positive) electrode potential
B. The metal with the more active (negative) electrode potential
C. Both metals at equal rates
D. Neither metal if they are the same alloy
CORRECT ANSWER: B. The metal with the more active (negative) electrode
potential
Rationale: In a galvanic couple immersed in an electrolyte, the more active metal
becomes the anode and corrodes preferentially while the more noble metal
becomes the cathode and is protected.
Question 3: Which form of corrosion is characterized by localized attack
beneath a surface deposit or in a shielded area where the bulk electrolyte has
limited access?
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,A. Uniform corrosion
B. Galvanic corrosion
C. Crevice corrosion
D. Erosion-corrosion
CORRECT ANSWER: C. Crevice corrosion
Rationale: Crevice corrosion occurs in restricted geometries where oxygen depletion
and concentration of aggressive ions create a highly aggressive local environment,
leading to rapid localized attack.
Question 4: What is the primary purpose of a sacrificial anode in a cathodic
protection system?
A. To increase the electrical resistance of the circuit
B. To corrode preferentially and supply electrons to the structure being protected
C. To act as a permanent barrier coating
D. To raise the potential of the structure into the active corrosion region
CORRECT ANSWER: B. To corrode preferentially and supply electrons to the
structure being protected
Rationale: Sacrificial anodes are made of more active metals (zinc, aluminum,
magnesium) that oxidize preferentially, providing a continuous supply of electrons
that polarize the protected structure cathodically.
Question 5: Which of the following is the most common cathodic reaction in
aerated neutral or alkaline aqueous solutions?
A. Hydrogen evolution
B. Oxygen reduction
C. Metal ion reduction
D. Chlorine evolution
CORRECT ANSWER: B. Oxygen reduction
Rationale: In the presence of dissolved oxygen, the predominant cathodic reaction
is the reduction of oxygen to hydroxide ions, which supports the anodic dissolution
of the metal.
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,Question 6: Stress corrosion cracking (SCC) requires the simultaneous presence
of which three factors?
A. High temperature, high pressure, and high velocity
B. Tensile stress, a susceptible material, and a specific corrosive environment
C. Compressive stress, a noble metal, and distilled water
D. Cyclic loading, a passive film, and high pH only
CORRECT ANSWER: B. Tensile stress, a susceptible material, and a specific
corrosive environment
Rationale: SCC is a synergistic process that occurs only when a susceptible alloy is
exposed to a particular environment while under tensile stress (applied or residual).
Question 7: Which type of coating failure is characterized by the formation of
small blisters filled with liquid at the coating–metal interface?
A. Undercutting
B. Blistering
C. Checking
D. Chalking
CORRECT ANSWER: B. Blistering
Rationale: Blistering results from osmotic or electrochemical processes that
generate liquid-filled blisters beneath the coating, often leading to subsequent
adhesion loss and underfilm corrosion.
Question 8: In impressed-current cathodic protection systems, what is the
function of the rectifier?
A. To convert AC power to controlled DC current for the anode bed
B. To measure soil resistivity
C. To serve as a sacrificial anode
D. To increase the resistance of the ground bed
CORRECT ANSWER: A. To convert AC power to controlled DC current for the
anode bed
Rationale: The rectifier transforms alternating current from the power source into
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, direct current that is driven through the anode bed to polarize the structure
cathodically.
Question 9: Which of the following metals is commonly used as a sacrificial
anode in seawater applications because of its high efficiency and relatively low
cost?
A. Platinum
B. Zinc
C. Titanium
D. Stainless steel
CORRECT ANSWER: B. Zinc
Rationale: Zinc anodes are widely used in seawater because they have a suitable
driving potential, high current capacity, and good efficiency when properly alloyed.
Question 10: What does a more negative (active) corrosion potential generally
indicate for a given metal in a specific environment?
A. Greater thermodynamic nobility
B. Greater thermodynamic tendency to corrode
C. Complete immunity to corrosion
D. Higher electrical conductivity
CORRECT ANSWER: B. Greater thermodynamic tendency to corrode
Rationale: A more negative potential indicates a greater driving force for the metal
to oxidize (corrode) relative to a more positive (noble) potential under the same
conditions.
Question 11: Which of the following is a primary advantage of organic
coatings for corrosion protection?
A. They completely eliminate the need for surface preparation
B. They provide a barrier that isolates the metal from the environment
C. They increase the electrical conductivity of the surface
D. They function exclusively as sacrificial anodes
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EXAM QUESTIONS AND VERIFIED
ANSWERS WITH RATIONALES
Question 1: Which of the following best describes the fundamental
electrochemical nature of most aqueous corrosion processes?
A. Purely chemical dissolution without electron transfer
B. Anodic metal oxidation coupled with cathodic reduction reactions involving
electron flow
C. Mechanical wear caused by fluid velocity alone
D. Thermal degradation of the metal lattice
CORRECT ANSWER: B. Anodic metal oxidation coupled with cathodic
reduction reactions involving electron flow
Rationale: Aqueous corrosion is an electrochemical process in which metal atoms at
anodic sites lose electrons (oxidation) while a reduction reaction occurs at cathodic
sites, completing the electrical circuit through the metal and the electrolyte.
Question 2: In a galvanic couple, which metal will preferentially corrode?
A. The metal with the more noble (positive) electrode potential
B. The metal with the more active (negative) electrode potential
C. Both metals at equal rates
D. Neither metal if they are the same alloy
CORRECT ANSWER: B. The metal with the more active (negative) electrode
potential
Rationale: In a galvanic couple immersed in an electrolyte, the more active metal
becomes the anode and corrodes preferentially while the more noble metal
becomes the cathode and is protected.
Question 3: Which form of corrosion is characterized by localized attack
beneath a surface deposit or in a shielded area where the bulk electrolyte has
limited access?
Page 1 of 78
,A. Uniform corrosion
B. Galvanic corrosion
C. Crevice corrosion
D. Erosion-corrosion
CORRECT ANSWER: C. Crevice corrosion
Rationale: Crevice corrosion occurs in restricted geometries where oxygen depletion
and concentration of aggressive ions create a highly aggressive local environment,
leading to rapid localized attack.
Question 4: What is the primary purpose of a sacrificial anode in a cathodic
protection system?
A. To increase the electrical resistance of the circuit
B. To corrode preferentially and supply electrons to the structure being protected
C. To act as a permanent barrier coating
D. To raise the potential of the structure into the active corrosion region
CORRECT ANSWER: B. To corrode preferentially and supply electrons to the
structure being protected
Rationale: Sacrificial anodes are made of more active metals (zinc, aluminum,
magnesium) that oxidize preferentially, providing a continuous supply of electrons
that polarize the protected structure cathodically.
Question 5: Which of the following is the most common cathodic reaction in
aerated neutral or alkaline aqueous solutions?
A. Hydrogen evolution
B. Oxygen reduction
C. Metal ion reduction
D. Chlorine evolution
CORRECT ANSWER: B. Oxygen reduction
Rationale: In the presence of dissolved oxygen, the predominant cathodic reaction
is the reduction of oxygen to hydroxide ions, which supports the anodic dissolution
of the metal.
Page 2 of 78
,Question 6: Stress corrosion cracking (SCC) requires the simultaneous presence
of which three factors?
A. High temperature, high pressure, and high velocity
B. Tensile stress, a susceptible material, and a specific corrosive environment
C. Compressive stress, a noble metal, and distilled water
D. Cyclic loading, a passive film, and high pH only
CORRECT ANSWER: B. Tensile stress, a susceptible material, and a specific
corrosive environment
Rationale: SCC is a synergistic process that occurs only when a susceptible alloy is
exposed to a particular environment while under tensile stress (applied or residual).
Question 7: Which type of coating failure is characterized by the formation of
small blisters filled with liquid at the coating–metal interface?
A. Undercutting
B. Blistering
C. Checking
D. Chalking
CORRECT ANSWER: B. Blistering
Rationale: Blistering results from osmotic or electrochemical processes that
generate liquid-filled blisters beneath the coating, often leading to subsequent
adhesion loss and underfilm corrosion.
Question 8: In impressed-current cathodic protection systems, what is the
function of the rectifier?
A. To convert AC power to controlled DC current for the anode bed
B. To measure soil resistivity
C. To serve as a sacrificial anode
D. To increase the resistance of the ground bed
CORRECT ANSWER: A. To convert AC power to controlled DC current for the
anode bed
Rationale: The rectifier transforms alternating current from the power source into
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, direct current that is driven through the anode bed to polarize the structure
cathodically.
Question 9: Which of the following metals is commonly used as a sacrificial
anode in seawater applications because of its high efficiency and relatively low
cost?
A. Platinum
B. Zinc
C. Titanium
D. Stainless steel
CORRECT ANSWER: B. Zinc
Rationale: Zinc anodes are widely used in seawater because they have a suitable
driving potential, high current capacity, and good efficiency when properly alloyed.
Question 10: What does a more negative (active) corrosion potential generally
indicate for a given metal in a specific environment?
A. Greater thermodynamic nobility
B. Greater thermodynamic tendency to corrode
C. Complete immunity to corrosion
D. Higher electrical conductivity
CORRECT ANSWER: B. Greater thermodynamic tendency to corrode
Rationale: A more negative potential indicates a greater driving force for the metal
to oxidize (corrode) relative to a more positive (noble) potential under the same
conditions.
Question 11: Which of the following is a primary advantage of organic
coatings for corrosion protection?
A. They completely eliminate the need for surface preparation
B. They provide a barrier that isolates the metal from the environment
C. They increase the electrical conductivity of the surface
D. They function exclusively as sacrificial anodes
Page 4 of 78
