Home / iGCSE Chemistry (0620) Core:9.5 Corrosion of metals: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:9.5 Corrosion of metals: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core Paper 1 - All Chapters
Question

The diagram shows an experiment to investigate how paint affects the rusting of iron.

What happens to the water level in tubes S and T?

 tube Stube T
Afallsrises
Bno changerises
Crisesfalls
Drisesno change
▶️ Answer/Explanation
Solution

Ans: D

This experiment demonstrates rusting which requires both oxygen and water:

1. Tube S (unpainted iron): Rusting occurs, consuming oxygen from the air inside the tube. This creates a partial vacuum, causing the water level to rise as atmospheric pressure pushes water up the tube.

2. Tube T (painted iron): The paint prevents oxygen and water from reaching the iron, so no rusting occurs. The water level remains unchanged.

Therefore, the correct observation is that the water level rises in tube S and shows no change in tube T, corresponding to option D.

Question

Which word equation represents the rusting of iron?

A) iron + oxygen + water → anhydrous iron(II) hydroxide
B) iron + oxygen → hydrated iron(II) oxide
C) iron + oxygen + water → anhydrous iron(III) hydroxide
D) iron + oxygen + water → hydrated iron(III) oxide

▶️ Answer/Explanation
Solution

Ans: D

Rusting of iron is a chemical reaction where iron reacts with oxygen and water to form hydrated iron(III) oxide, commonly known as rust. The key points are:

  1. Water must be present for rusting to occur (eliminates option B)
  2. The product is iron(III) oxide, not iron(II) (eliminates options A and B)
  3. The product is hydrated (contains water molecules in its structure), not anhydrous (eliminates option C)

The correct equation is: iron + oxygen + water → hydrated iron(III) oxide, which matches option D.

Question

 The diagrams show experiments to investigate rusting of iron nails.

In which test-tubes do the nails rust?
A 1 only

B 1 and 2 only

C 1 and 3 only

D 1,2 and 3

▶️Answer/Explanation

Ans:B

Rust is formed when iron reacts with oxygen and water to create iron oxide. Boiling water eliminates dissolved oxygen, which is a crucial component in the rusting process. When the water is boiled, the oxygen molecules present in the water escape as gas, leaving behind oxygen-depleted water. Also, its top is also closed, so atmospheric air cannot enter.

Question

Which pollutants are responsible for the erosion of buildings and statues?

1 carbon monoxide
2 oxides of nitrogen
3 sulfur dioxide
A 1, 2 and 3           B 1 and 2 only           C 2 and 3 only           D 3 only

▶️Answer/Explanation

Ans: C

Acid rain is formed when sulfur dioxide and nitrogen oxides react with water, oxygen, and other chemicals in the atmosphere. It creates acidic precipitation, which can cause significant damage to buildings and statues made of limestone, marble, and other calcareous stones. Acid rain reacts with the calcium carbonate present in these stones, dissolving and eroding the surfaces.

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