Why does iron remain protected from rusting for some time even when a small scratch develops in the zinc coating of galvanisation?
Answer and explanation
Correct answer: Nearby zinc, being more reactive than iron, oxidises first and provides sacrificial protection.
Zinc is more reactive than iron. When a small scratch occurs and moisture is present, zinc acts as the anode and oxidises preferentially. This sacrificial action keeps the exposed iron cathodic and protects it from rusting. Option C reverses these roles: in galvanisation, zinc is the anode, not iron. Iron can rust after the available zinc has been substantially consumed and it is exposed to air and moisture.
Frequently asked questions
What is the correct answer to this question?
Nearby zinc, being more reactive than iron, oxidises first and provides sacrificial protection.
Why is this the correct answer?
Zinc is more reactive than iron. When a small scratch occurs and moisture is present, zinc acts as the anode and oxidises preferentially. This sacrificial action keeps the exposed iron cathodic and protects it from rusting. Option C reverses these roles: in galvanisation, zinc is the anode, not iron. Iron can rust after the available zinc has been substantially consumed and it is exposed to air and moisture.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
