| Difficulty | Secondary School | High school/other |
| ★ | Basic | Easy |
| ★★ | Demanding | Basic |
| ★★★ | Demanding | |
| ★★★★ | Difficult | |
| ★★★★★ | Very difficult |
Explore the dependence of gas volume and pressure on a graphical representation.
Answer: It is noticed that the pressure is inversely proportional to the volume, $p\propto\frac{1}{V}$