Question
Mild steel is galvanized to prevent corrosion of the iron.
Which statements about galvanizing are correct?
- Galvanizing prevents corrosion because the zinc forms an alloy.
- If the coating is damaged, water and oxygen do not corrode the iron.
- Zinc is a sacrificial metal and corrodes in preference to iron.
A 1 and 2 B 1 and 3 C 2 only D 2 and 3
Answer/Explanation
Ans:
D
Question
Covering iron with zinc prevents the iron from rusting even when the zinc is scratched. Covering iron with tin prevents the iron from rusting, but when the tin is scratched the iron underneath starts to rust.
Which statement is correct?
A Both tin and zinc prevent iron from rusting by sacrificial protection.
B Both tin and zinc prevent iron from rusting by stopping water and carbon dioxide reaching the
iron.
C Tin is more reactive than iron and prevents iron from rusting until it is scratched.
D Zinc loses electrons more easily than iron and prevents iron from rusting by corroding first.
Answer/Explanation
Ans: D
Question
Aluminium objects do not need protection from corrosion.
Iron objects must be protected from corrosion.
Which statement explains why aluminium resists corrosion?
A Aluminium does not form ions easily.
B Aluminium does not react with water or air.
C Aluminium has a protective oxide layer.
D Aluminium is below iron in the reactivity series.
Answer/Explanation
Ans: C
Question
The diagram shows an experiment to investigate how paint affects the rusting of iron.
What happens to the water level in tubes P and Q?
Answer/Explanation
Ans:
D