CAIE IGCSE Physics 2.1.2.6 Forces & distances between particles
Practise linking particle spacing, motion and attractive forces to why solids keep shape, liquids flow and gases fill containers.
- Syllabus
- 2026–2028
- Course
- Physics 0625
Practise linking particle spacing, motion and attractive forces to why solids keep shape, liquids flow and gases fill containers.
Fig. 4.1 shows a metal pan on an electric hotplate. The pan contains 200 cm3 of water.

Fig. 4.1
The pan is heated. The temperature of the water in the pan increases.
The water boils and leaves the liquid as a gas.
Explain, in terms of forces and distances between particles, why the gas occupies a much greater volume than it does as a liquid.
(attractive) forces (between particles are much) greater in liquids (than in gases)
B1
particles in gases are (much) further apart (than in liquids)
B1