Home / iGCSE Chemistry 0620 Extended – 9.3 Alloys and their properties- Exam Style Questions Paper 2

iGCSE Chemistry 0620 Extended - 9.3 Alloys and their properties- Exam Style Questions Paper 2- New Syllabus

iGCSE Chemistry MCQ (Extended) Paper 2 - All Chapters

Question

Brass is an alloy of copper.

Which statement about brass or copper is correct?

A. Brass does not conduct electricity because it is a compound.
B. Copper conducts electricity because its atoms are free to move.
C. Brass is harder than copper because its layers of atoms cannot easily slide over each other.
D. Copper is stronger than brass because it is a pure metal.

▶️ Answer/Explanation
Brass is an alloy of copper and zinc (a mixture, not a compound), and it still conducts electricity, so A is wrong. Copper conducts electricity because of delocalised electrons, not because its atoms are free to move, so B is wrong. In pure copper, atoms are arranged in regular layers that can slide over each other easily. In brass, zinc atoms of different size disrupt these layers, preventing easy sliding, making brass harder and stronger than pure copper. This makes C correct and D wrong.
✅ Answer: (C)

Question

Brass is a mixture of copper and zinc.

Which statement describes and explains the relative strength of brass compared to copper?

A. Brass is stronger than copper because the layers of atoms in brass cannot easily slide over each other.
B. Brass is stronger than copper because the intermolecular forces are greater in brass than in copper.
C. Brass is weaker than copper because the layers of atoms slide more easily over each other in brass than in copper.
D. Brass is weaker than copper because the intermolecular forces are weaker in brass than in copper.

▶️ Answer/Explanation
Brass is an alloy—zinc atoms are a different size from copper atoms, so they disrupt the regular layers in the metallic lattice. When a force is applied, the layers cannot easily slide over each other because of this distortion, making brass harder and stronger than pure copper. The mention of intermolecular forces is incorrect for metallic bonding.
✅ Answer: A

Question

Which statement about alloys is correct?

A. Alloys are pure metal elements.
B. At least two or more metals react together to make alloys.
C. Alloys can be harder and stronger than a pure metal.
D. Steel is not an alloy because it can contain the non-metal carbon.

▶️ Answer/Explanation
Pure metals have rows of uniformly sized atoms that slide over one another easily when pressure is applied, making them malleable. When a secondary element with differently sized atoms is mixed in to create an alloy, it distorts the orderly arrangement. This disruption blocks the layers from sliding past each other cleanly, making alloys significantly harder and physically stronger than pure elemental metals.
✅ Answer: (C)
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