IGCSE Chemistry Paper-1: Specimen Questions with Answers 19 - 20 of 99
Question number: 19
Question
Which alloy contains non-metal as its constituents?
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | Amalgam |
|
| b. | Brass |
|
| c. | Steel |
|
| d. | Bronze |
|
Answer
c.Explanation
Steels are alloys of iron and other elements, primarily carbon, widely used in construction and other applications. The carbon content of steel is between 0.002 % and 2.1 % by weight for plain iron-carbon alloys. These values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an iron-carbon alloy.
Question number: 20
Question
Aluminium is an important metal with many uses. Its properties are:
1 It is a good conductor of heat.
2 It has a low density.
3 It has an oxide layer that prevents corrosion.
What explains the use of aluminium for cooking and storing food?
Choices
| Choice (4) | Response | |
|---|---|---|
| a. | 1 and 2 only |
|
| b. | 1,2 and 3 |
|
| c. | 2 and 3 only |
|
| d. | 1 only |
|
Answer
b.Explanation
Aluminium is now the second most widely used metal in the world. The above properties can be explained as:
- Aluminium is an excellent conductor of heat and electricity. An aluminium conductor weighs approximately half as much as a copper conductor having the same conductivity.
- With a density one third that of steel, 2.700 kg/m3. The low density of aluminium accounts for it being lightweight but this does not affect its strength.
- Aluminium reacts with the oxygen in the air to form an extremely thin layer of oxide. This layer is dense and provides excellent corrosion protection. The layer is self-repairing if damaged.
Therefore all the above three properties are useful.