Particulate nature of matter

In which changes do the particles move further apart?

• W and X

• W and Z

• X and Y

• Y and Z

Which change of state takes place during evaporation?

• gas to liquid

• liquid to gas

• liquid to solid

• solid to gas

A sugar cube is dropped into a hot cup of tea.

The tea is not stirred.

Which statement explains why the tea becomes sweet?

• The heated water molecules penetrate the sugar cube.

• The hot tea causes the sugar to melt.

• The sugar cube dissolves and its molecules diffuse.

• The sugar molecules get hot and evaporate.

Which statement is an example of diffusion?

• A kitchen towel soaks up some spilt milk.

• Ice cream melts in a warm room.

• Pollen from flowers is blown by the wind.

• The smell of cooking spreads through a house.

A few drops of perfume were spilt on the floor. A few minutes later the perfume could be smelt a

few metres away.

Which two processes had taken place?

• distillation and condensation

• distillation and diffusion

• evaporation and condensation

• evaporation and diffusion

‘Particles moving very slowly from an area of high concentration to an area of low

concentration.’

Which process is being described above?

• a liquid being frozen

• a solid melting

• a substance diffusing through a liquid

• a substance diffusing through the air

In which substance are the particles close together and slowly moving past each other?

• air

• ice

• steam

• water

The diagram shows how the molecules in the exhaust gases diffuse into the air.

Which statement describes what happens to these molecules next?

• The molecules fall to the ground because they are heavier than air molecules.

• The molecules go back together as they cool.

• The molecules spread further into the air.

• The molecules stay where they are.

A gas jar of bromine vapour and a gas jar of air are set up as shown in diagram 1.

The glass slide is removed. Diagram 2 shows the appearance of the gas jars after one hour.

Which statement explains why the bromine and air mix together?

• Bromine is denser than air.

• Bromine is lighter than air.

• Bromine molecules moved upwards and molecules in air moved downwards.

• Molecules in bromine and air moved randomly.

A liquid is heated until it boils.

Which result shows that the liquid in the test-tube is pure water?

• Condensation forms at the top of the test-tube.

• Steam is produced.

• The thermometer reads 100 °C.

• There is nothing left behind in the test-tube.