Observation

Most of the candidates who attempted these questions responded well. However, some used wrong terms, such as ‘joined’ while explaining alloy instead of ‘mixture’. The required responses to these questions are given below.
1a.       (i) An alloy is a mixture of two or more metals chemically combined.
            (ii) Examples of alloy are

• brass;
• bronze;
• duralumin;
• constantan;
• pewter;
• aluminium bronze;
• steel;
• stainless steel;
• solder.

b.         Difference between ferrous and non-ferrous metals are

• ferrous metals contain iron while non-ferrous metals do not contain iron;
• ferrous metals are magnetic while non-ferrous metals are non-magnetic.

c.         Properties of

(i) Chromium Steel

• It is hard.
• It is corrosion resistant.
• It has high strength.
• It resists wear.
• It is lustrous.

(ii) Brass

• It is corrosion resistant.
• It is malleable.
• It has good appearance.
• It is ductile.

 (iii) Bronze

• It is easily machined.
• It resists corrosion.
• It polishes well.
• It resists wear.
• It can be heat treated.

d.         Aluminium is used for making electric cables because

• it is light in weight.
• it has excellent electrical conduction.
• it is relatively cheap.
• it is corrosion resistant.