A technician finds two unlabelled white solids, X and Y. The technician tests both solids.
The table shows the results.
| Test | Solid X | Solid Y |
|---|---|---|
| melting point in °C | 801 | 80 |
| dissolves in water? | yes | no |
| conducts electricity when solid? | no | no |
| conducts electricity when molten? | yes | no |
Identify which solid is ionic. Give one reason for your answer from the table.
Solid Y is a simple molecular substance. Explain why solid Y has a low melting point.
Explain why solid Y does not conduct electricity when it is molten.
Explain why solid X conducts electricity when molten but not when solid.
Predict whether a solution of X in water conducts electricity.
48 exam-style questions on Edexcel GCSE Chemistry 2.5 Types of substance, covering 2.5.1 Classifying substances by structure and bonding, 2.5.2 Properties of ionic and simple molecular substances, 2.5.3 Giant covalent structures: diamond and graphite, 2.5.4 Fullerenes, graphene and simple polymers, 2.5.5 Properties of metals and non-metals, and 2.5.6 Limitations of bonding models and representations. Each one has a worked solution and a mark scheme showing where the marks go.