T1.1.2 Gas pressure and particles Quiz: KS3 Chemistry, Unit 1

The 20 questions

1. What causes the pressure exerted by a gas on the walls of its container?

   • Gas particles being attracted to the walls by a strong pull that holds them there
   • Gas particles becoming larger inside the container and pushing outwards
   • Gas particles stopping and settling on the base of the container under gravity
   • Gas particles colliding with the walls of the container

2. What happens to the pressure of a fixed mass of gas if its volume is decreased at constant temperature?

   • The pressure stays the same
   • The pressure becomes zero
   • The pressure decreases
   • The pressure increases

3. What happens to gas pressure if a gas is heated in a sealed container of fixed volume?

   • The pressure stays the same because the particles stop moving and rest on the walls
   • The pressure increases because particles move faster and hit the walls harder and more often
   • The pressure decreases because the particles slow down and hit the walls less often
   • The pressure drops to zero because the particles settle at the bottom of the container

4. A football is pumped up with more air. Why does the pressure inside increase?

   • The air particles shrink when more air is added, so they take up less room inside
   • More air particles hit the inside surface of the ball every second
   • The air particles become heavier and sink to the bottom, lowering the pressure on the top
   • The air particles stop colliding with the ball, so the pressure builds up slowly

5. Which factor does NOT directly change the pressure of a gas in a sealed container?

   • The colour of the container
   • The number of gas particles present
   • The volume of the container
   • The temperature of the gas

6. Why does a gas exert more pressure when its particles are squeezed into a smaller volume?

   • Particles move slower and press harder against the walls when they are squeezed
   • Particles hit the walls more often in a smaller space
   • Particles stick to the walls of the container and pull them inwards
   • Particles become larger and push harder against the walls of the container

7. A syringe is sealed with trapped air and the plunger is pushed in. What happens to the air pressure?

   • It stays exactly the same
   • It decreases
   • It increases
   • It becomes zero

8. Which unit is used to measure gas pressure?

   • Kilogram (kg)
   • Pascal (Pa)
   • Litre (l)
   • Degree Celsius (°C)

9. Which change would make a fixed mass of gas in a sealed container exert more pressure?

   • Cooling it while the volume stays the same
   • Making the container larger without changing the gas
   • Heating it while the volume stays the same
   • Letting some of the gas escape

10. A sealed bottle of air is left in strong sunlight and the lid pops off. Which explanation fits the particle model?

    • The air particles turn into a solid and shrink, so the lid is pulled down
    • The air particles stop moving and expand to fill the bottle and burst the lid
    • The air particles are attracted out of the bottle by the warm sunlight outside
    • The air particles move faster and push harder on the lid

11. Why do gas particles hit the walls of a container at all?

    • They are pulled towards the walls by gravity only
    • They are held in a rigid pattern by the lid
    • They are fixed to the walls by chemical bonds
    • They are constantly moving in random directions

12. A student says gas pressure is caused by particles sticking to the walls. What is wrong with this?

    • Gas particles are too small to hit the walls, so the pressure comes from the lid
    • Gas particles bounce off the walls rather than sticking to them
    • Gas particles never touch the container at all, so no pressure is produced
    • Gas particles only exist in liquids and so cannot press on the container walls

13. Which pair of changes would increase gas pressure in a sealed container?

    • Increasing the volume and removing gas particles from the sealed container
    • Decreasing the temperature and removing gas particles from the sealed container
    • Increasing the temperature and adding more gas particles
    • Decreasing the temperature and adding more gas particles to the same volume

14. A car tyre is pumped up on a warm day and goes flat-looking in a cold garage. Which explanation is best?

    • Cooler air particles are heavier and sink to the base of the tyre, lowering the pressure
    • Cooler air particles move more slowly and hit the walls less hard
    • Cooler air particles become larger and leak out through the valve of the tyre
    • Cooler air particles stop colliding with the inside of the tyre and drift off

15. What does the particle model predict will happen to the speed of gas particles when a gas is heated?

    • The particles stay at the same speed
    • The particles stop moving
    • The particles slow down
    • The particles speed up

16. A sealed gas syringe is heated at constant volume. Which sequence correctly describes what happens?

    • Particles gain energy, move faster, hit walls harder and more often, so pressure rises
    • Particles gain energy but stop hitting the walls, so the pressure falls as the volume rises
    • Particles lose energy, move more slowly, hit walls less often, so the pressure falls steadily
    • Particles lose energy and stick together into clumps, so the pressure rises as they cool

17. Why does compressing a gas increase its pressure even though the particles themselves do not change?

    • The same particles now collide with the walls more frequently in less space
    • The particles change into a liquid when squeezed, and the liquid exerts the pressure
    • The particles grow larger when squeezed together, so they strike the walls with more force
    • The particles become heavier when squeezed together and press down harder on the walls

18. Two sealed containers hold the same gas at the same temperature. Container A has twice the volume of container B. Which statement is correct?

    • Container B has the higher pressure because its particles hit its walls more often
    • Container A has the higher pressure because its particles are bigger and collide more
    • Both have the same pressure because the gas is the same gas at the same temperature
    • Container A has the higher pressure because its particles are more spread out and push harder

19. Why does a sealed crisp packet puff up when taken up a mountain?

    • The gas inside shrinks as it rises up the mountain, so the packet puffs up around it
    • Atmospheric pressure is lower at height, so the gas inside pushes the packet outwards
    • Air particles are heavier at height and sink into the packet, pushing it out
    • The packet absorbs water vapour from the thin air and this makes it swell outwards

20. Why does gas pressure act in all directions inside a container?

    • Gas particles are fixed in layers that press sideways against the container walls
    • Gas particles only move downward because of gravity, so pressure acts from above
    • Gas particles move randomly and strike surfaces from every direction
    • Gas particles move only along the centre of the container and never reach the sides

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