If you put a drop of coloured liquid into a glass of cold water and leave it to stand without stirring, the colour spreads through the water. This is called:

• divination

• dissolving

• dispersion

• diffusion

Which of these changes involve the mixing of particles of different substances?

• water boiling in a kettle

• chocolate melting in your hand

• particles of dust moving about in the air

• perfume being smelled across a room

Gases spread out and mix together more quickly than liquids because gas particles:

• are lighter.

• are heavier.

• are further apart.

• are closer together.

If you put some sugar into cold water and leave it without stirring, the sugar will eventually dissolve and mix with the water. This happens because:

• particles are extremely small.

• particles in a liquid are always moving.

• water particles are bigger than sugar particles.

• sugar particles are bigger than water particles.

In Brownian motion specks of dust or smoke can be seen to:

• change shape.

• vibrate in the same place.

• move quickly in straight lines.

• move jerkily in different directions.

To observe Brownian motion you need to:

• use a microscope.

• measure distance accurately.

• observe carefully for a few days.

• heat different solids, liquids and gases.

Brownian motion is caused by:

• vibrations in solid particles.

• spaces between gas particles.

• particles getting bigger when heated.

• moving particles hitting specks of matter.

All solids:

• have a fixed volume and take the shape of their container.

• have a fixed volume and a fixed shape.

• will spread out until their volume has doubled.

• can change their volume but not their shape.

Which of the three states of matter are usually easy to compress (squash)?

• solids and liquids

• liquids only

• gases only

• gases and liquids

In which state are particles close together, and vibrate around fixed points?

• gases only

• liquids only

• solids only

• all three states