Why does exposed iron remain protected from rusting for some time even when the zinc coating in galvanisation is scratched?
Answer and explanation
Correct answer: Zinc is more reactive than iron and oxidises first, providing sacrificial protection.
Zinc is more reactive than iron. Even if the coating is scratched, zinc oxidises preferentially and supplies electrons that prevent or slow the oxidation of the exposed iron. This is called sacrificial protection. Option C is incorrect because air and moisture can reach a scratch; the protection mainly results from zinc being more reactive than iron.
Frequently asked questions
What is the correct answer to this question?
Zinc is more reactive than iron and oxidises first, providing sacrificial protection.
Why is this the correct answer?
Zinc is more reactive than iron. Even if the coating is scratched, zinc oxidises preferentially and supplies electrons that prevent or slow the oxidation of the exposed iron. This is called sacrificial protection. Option C is incorrect because air and moisture can reach a scratch; the protection mainly results from zinc being more reactive than iron.
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.
