Home / iGCSE Chemistry (0620) Core:9.3 Alloys and their properties: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:9.3 Alloys and their properties: Exam Style Questions Paper 1- New Syllabus

iGCSE Chemistry (0620) Core Paper 1 - All Chapters

Question

Steel is a mixture of iron and one or more other elements.
The table gives some information about three common types of steel.
Which rows identify a type of steel that is suitable to make cutlery?
A. 1 and 2
B. 1 only
C. 2 and 3
D. 3 only
▶️ Answer/Explanation
Correct Option: D

Detailed solution:

Cutlery needs to be hard, strong, and resistant to corrosion (rusting) since it comes into contact with water and food. Stainless steel (type 3) is an alloy containing chromium and nickel, which makes it hard and highly resistant to rust. High-carbon steel (type 1) is brittle and corrodes, while low-carbon steel (type 2) is too soft and still corrodes. Therefore, only stainless steel is suitable for cutlery.

Question

18 carat gold contains $75\%$ gold and $25\%$ copper by mass.
Which statements about 18 carat gold are correct?
  1. It is a mixture.
  2. It is a compound.
  3. It is an alloy.
  4. It conducts electricity.
A. 1, 2 and 4
B. 1, 3 and 4
C. 1 and 3 only
D. 2 and 3
▶️ Answer/Explanation
Correct Option: B

Detailed solution:

18 carat gold is made up of 75% gold and 25% copper mixed together physically, not chemically combined, so it is a mixture (statement 1 correct) and not a compound (statement 2 incorrect). Because it is a mixture of metals, it is specifically called an alloy (statement 3 correct). Like pure gold and copper, 18 carat gold contains delocalised electrons that can move freely through the structure, so it conducts electricity (statement 4 correct). Therefore, statements 1, 3, and 4 are all correct, making option B the right choice.

Question

Pure metals can be combined to make alloys.
Why are the alloys sometimes used rather than the metals they are made from?
A. Alloys are easier to extract and cheaper.
B. Alloys are easier to hammer into different shapes.
C. Alloys are harder and keep their shape better.
D. Alloys contain only atoms of the same size but pure metals do not.
▶️ Answer/Explanation
Correct Option: C

Detailed solution:

The main reason we mix metals into alloys is to make them stronger and more useful. Pure metals have a regular arrangement of atoms where layers can slide over each other easily, making them soft and easily bent out of shape. In an alloy, different-sized atoms are introduced which disrupt the neat layers and stop them from sliding. This makes the alloy harder, stronger, and better at holding its shape under stress. They are not necessarily cheaper or easier to extract, and they are definitely not easier to hammer into shape than the soft pure metals.

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