Argon is obtained from liquid air. The table shows the boiling points of the three main gases in air.
| Gas | Boiling point in ∘C^\circ\mathrm{C}∘C |
|---|---|
| nitrogen | -196 |
| argon | -186 |
| oxygen | -183 |
A sample of liquid air at −200 ∘C-200\,^\circ\mathrm{C}−200∘C is warmed slowly to −185 ∘C-185\,^\circ\mathrm{C}−185∘C and kept at that temperature. Assume each gas boils off completely at its boiling point.
Which description is correct?
Only nitrogen has boiled off; argon and oxygen remain as liquids
Argon has boiled off first; nitrogen and oxygen remain as liquids
Oxygen has boiled off; nitrogen and argon remain as liquids
Nitrogen and argon have boiled off; oxygen remains as a liquid
44 exam-style questions on Edexcel GCSE Chemistry 7.3 Group 0, covering 7.3.1 The noble gases. Each one has a worked solution and a mark scheme showing where the marks go.