Why can a gas be compressed easily into a smaller volume?

• The particles are far apart.

• The particles do not attract each other.

• The particles move randomly.

• The volume of each particle can be reduced.

In which states of matter is Brownian motion observed?

• gases, liquids and solids

• gases and liquids only

• gases and solids only

• liquids and solids only

A student investigates the relationship between the pressure of a gas and its volume at constant temperature. He records his results in the table. What is the correct conclusion from the experiment?

• The volume decreases when the pressure increases.

• The volume increases when the pressure increases.

• The volume initially increases when the pressure increases, but then decreases.

• The volume is independent of the pressure.

A sealed bottle of constant volume contains air. The air in the bottle is heated by the Sun. What is the effect on the average speed of the air particles in the bottle and the average distance between them?

• decreases, decreases

• decreases, stays the same

• increases, increases

• increases, stays the same

Which graph shows the relationship between the pressure p of a fixed mass of gas and its volume V at a constant temperature?

• C
• A

• B

• D

A gas is contained in a cylinder by a movable piston. The gas is heated so that it expands at constant pressure. How is the force of each collision of a gas particle with the piston affected and how does the frequency of collisions between the gas particles and the piston change?

• Force increases, Frequency decreases

• Force increases, Frequency increases

• Force stays the same, Frequency decreases

• Force stays the same, Frequency increases

The volume of a fixed mass of gas is varied. The temperature remains constant. Which graph shows how the pressure p of the gas varies with volume V?

• D
• A

• B

• C

Liquids are difficult to compress whereas gases can be compressed easily. Explain, in terms of particles, why it is difficult to compress liquids.

• Because liquid particles are closely packed with little space between them.

• Because liquid particles are far apart with a lot of space between them.

• Because liquid particles move freely and rapidly in all directions.

• Because liquid particles are arranged in a fixed, rigid structure.

Gases, liquids and solids are made up of small particles.

Which row gives the relative separation of the particles?

• C
• A

• B

• D

At the surface of a liquid, the more energetic molecules can escape from the liquid into the atmosphere. Which name is given to this process?

• boiling

• condensation

• evaporation

• melting