The table gives some properties of three substances, X, Y and Z.
Table: The melting point and the electrical conductivity of three substances
| Substance | Melting point in ∘C^\circ\text{C}∘C | Conducts electricity when solid | Conducts electricity when molten |
|---|---|---|---|
| X | 1074 | no | yes |
| Y | 1085 | yes | yes |
| Z | -95 | no | no |
Give the letter of the substance that consists of small molecules.
Give a reason for your answer.
Substance Y is a metal.
Explain why substance Y conducts electricity when it is solid.
Substance X is an ionic compound.
Explain why substance X does not conduct electricity when it is solid but does conduct electricity when it is molten.
42 exam-style questions on AQA GCSE Chemistry 2.2 How bonding and structure are related to the properties of substances, covering 2.2.1a The three states of matter, 2.2.1b Limitations of the simple particle model, 2.2.2 State symbols in chemical equations, 2.2.3 Properties of ionic compounds, 2.2.4 Properties of small molecules, 2.2.5 Polymers, 2.2.6 Giant covalent structures, 2.2.7 Properties of metals and alloys, and 2.2.8 Metals as conductors. Each one has a worked solution and a mark scheme showing where the marks go.