Questions on Corrosion
Multiple-Choice Questions – Corrosion
1. What is corrosion?
A) Formation of crystals in metals
B) Breaking of covalent bonds
C) Slow destruction of materials by chemical reactions with the environment
D) Polishing of a metal surface
E) Heating metals to high temperatures
2. Which metal is most commonly associated with rusting?
A) Copper
B) Zinc
C) Gold
D) Iron
E) Silver
3. What is the main chemical component of rust?
A) Fe₂O₃·xH₂O
B) CuSO₄
C) ZnCl₂
D) AgNO₃
E) NaOH
4. Corrosion is a type of:
A) Combustion
B) Neutralization
C) Redox reaction
D) Precipitation
E) Polymerization
5. What condition does not promote corrosion?
A) Moisture
B) Oxygen
C) Acids
D) Dry air
E) Salts
6. Which metal is most resistant to corrosion?
A) Iron
B) Aluminum
C) Zinc
D) Gold
E) Magnesium
7. Which process is often used to protect iron from rusting?
A) Fermentation
B) Electrolysis
C) Galvanization
D) Polymerization
E) Distillation
8. What is sacrificial protection?
A) Using expensive metals to replace corroded ones
B) Allowing a weaker metal to corrode instead of a stronger one
C) Coating metals with non-metals
D) Cleaning a metal surface with acid
E) Painting metals with insulating paint
9. Which metal is commonly used as a sacrificial anode to protect iron?
A) Silver
B) Zinc
C) Copper
D) Tin
E) Lead
10. The rusting of iron is faster in:
A) Dry conditions
B) Pure water
C) Saltwater
D) Ice
E) Vacuum
11. Which part of the redox reaction is the iron in during corrosion?
A) Neutral
B) Reduced
C) Oxidized
D) Electrically inactive
E) Not involved
12. What is the effect of corrosion on a metal's properties?
A) Increases conductivity
B) Strengthens the structure
C) Decreases strength and durability
D) Improves flexibility
E) Makes the metal shinier
13. Which of the following is not a method of corrosion prevention?
A) Painting
B) Galvanizing
C) Electroplating
D) Burning
E) Applying grease
14. Which environmental factor most accelerates corrosion in coastal areas?
A) Wind
B) Carbon dioxide
C) Salt (NaCl)
D) Sand
E) Pressure
15. Stainless steel resists corrosion because it contains:
A) Zinc
B) Magnesium
C) Chromium
D) Lead
E) Sodium
16. The corrosion of aluminum forms:
A) Aluminum hydroxide
B) Aluminum oxide
C) Aluminum sulfide
D) Aluminum carbonate
E) Pure aluminum
17. Which is true about rust?
A) It protects iron from further corrosion
B) It forms a hard, protective layer
C) It flakes off and exposes more metal
D) It is formed only in acidic environments
E) It is silver in color
18. Which chemical equation correctly represents the rusting of iron?
A) Fe + H₂O → FeH₂O
B) 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃
C) Fe + O₂ → FeO
D) Fe + CO₂ → FeCO₃
E) Fe + NaCl → FeCl
19. Anodic protection involves:
A) Applying a voltage to keep metal reduced
B) Coating the metal with oil
C) Making the metal the anode to corrode first
D) Exposing the metal to air
E) Spraying with salt solution
20. What role does oxygen play in corrosion?
A) It protects the metal surface
B) It cools the metal
C) It acts as an oxidizing agent
D) It slows down reactions
E) It forms hydrogen
Answers with Explanations
1. C – Corrosion is the slow chemical breakdown of materials, especially metals, due to environmental exposure.
2. D – Iron is the metal that rusts, forming iron oxide.
3. A – Rust is mainly hydrated iron(III) oxide (Fe₂O₃·xH₂O).
4. C – Corrosion is a redox process (oxidation of the metal).
5. D – Dry air lacks moisture, which is necessary for most corrosion.
6. D – Gold is a noble metal and highly resistant to corrosion.
7. C – Galvanization is coating iron with zinc to prevent rust.
8. B – Sacrificial protection uses a more reactive metal to corrode instead.
9. B – Zinc is commonly used as a sacrificial anode.
10. C – Corrosion is faster in saltwater due to better conductivity.
11. C – Iron is oxidized in corrosion (loses electrons).
12. C – Corrosion weakens the metal and reduces durability.
13. D – Burning is not a corrosion-prevention method.
14. C – Salt accelerates corrosion by increasing conductivity.
15. C – Chromium forms a protective oxide layer in stainless steel.
16. B – Aluminum forms a protective oxide layer (Al₂O₃).
17. C – Rust is flaky and exposes more iron, worsening corrosion.
18. B – This is the correct balanced equation for rust formation.
19. A – Anodic protection uses an external voltage to keep the metal passive.
20. C – Oxygen is the oxidizing agent in corrosion
- Questions on Assigning Oxidation Numbers and Changes in Reactions
- Questions about Identifying Redox Reactions
- Questions on Balancing Redox Reactions
- Chemistry Questions with Answers Key.
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