Metals, alloys and crystals

Which name is given to mixtures of metals?

• alloys

• compounds

• ores

• salts

• A

• B

• C

• D

Diamond and graphite are macromolecules.

Which statement about diamond and graphite is not correct?

• They are giant structures with high melting points.

• They are non-conductors of electricity.

• They contain only atoms of a non-metal.

• They have covalent bonds between the atoms.

Solder is an alloy of lead and tin. It is used for joining pieces of metal.

Which statement about solder is correct?

• It can be represented by a chemical formula.

• It contains a mixture of lead and tin.

• It contains lead and tin chemically combined.

• It has a higher melting point than lead or tin.

Rescuers are drilling through fallen rock in order to rescue some men trapped in a cave. The drill needs lubricating from time to time.

The following statements were made about the materials used for the drill tip and the lubricant and the reasons for their use.

1  Diamond was used for the drill tip as it does not conduct electricity.

2  Diamond was used for the drill tip as it is very hard.

3  Graphite was used as the lubricant as it conducts electricity.

4  Graphite was used as the lubricant as it is soft and flaky.

Which statements are correct?

• 1 and 3

• 1 and 4

• 2 and 3

• 2 and 4