Substances P, Q and R are candidate heat-transfer fluids. Each substance consists of small molecules.
The table shows data for substances P, Q and R.
| Substance | Number of atoms in one molecule | Boiling point in ∘C^\circ\text{C}∘C |
|---|---|---|
| P | 11 | -42 |
| Q | 14 | -1 |
| R | 17 | 36 |
Explain the pattern in boiling point shown by the data. Explain what happens to the covalent bonds in the molecules when one of the substances boils.
84 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.