A chemist investigates the melting point of some substances that may contain benzoic acid as shown in the table.
The melting point of pure benzoic acid is 122∘C122^\circ\text{C}122∘C.
| Substance | Melting point (∘C^\circ\text{C}∘C) |
|---|---|
| 1 | 122 |
| 2 | 101 |
| 3 | 115 - 121 |
| 4 | 124 - 128 |
Which statement about the results is correct?
All of the substances contain benzoic acid.
Substance 2 does not contain benzoic acid.
Substance 3 is pure benzoic acid.
Substance 4 is impure benzoic acid.
46 exam-style questions on OCR GCSE Chemistry Purity and separating mixtures. Each one has a worked solution and a mark scheme showing where the marks go.