A student tests four solids, W, X, Y and Z.
The table shows the results.
| Substance | Melting point (°C) | Conducts electricity when solid? | Conducts electricity when molten? | Other observations |
|---|---|---|---|---|
| W | above 3500 | yes | not tested | soft, grey and slippery; crumbles when bent |
| X | 770 | no | yes | hard, brittle crystals |
| Y | 44 | no | no | soft, white and waxy |
| Z | 1085 | yes | yes | shiny; can be bent into shape |
Which substance is made of simple molecules?
Give one reason from the table for your answer.
Substance X is an ionic compound.
Explain why X conducts electricity when molten but not when solid.
A student says:
"W must be a metal because it conducts electricity when solid."
Evaluate the student's statement. Use the data in the table.
Z is a metal.
Explain why Z has a high melting point.
60 exam-style questions on OCR GCSE Chemistry 2.3 Properties of materials, covering 2.3.1 Carbon bonding and the variety of organic compounds, 2.3.2 Diamond, graphite, fullerenes and graphene, 2.3.3 Bond strength, changes of state and predicting states, 2.3.4 Bulk properties and types of bonding, and 2.3.5 Nanoparticles: scale, surface area, uses and risks. Each one has a worked solution and a mark scheme showing where the marks go.