A student notices that the air near the ceiling of a heated room is warmer than the air near the floor. This is due to convection.
Which statement explains why this happens?
Warm air is less dense than cold air, so it rises towards the ceiling.
Cold air is less dense than warm air, so it rises towards the ceiling.
The molecules in cold air have more kinetic energy than those in warm air, so they move towards the ceiling faster.
The molecules in warm air are closer together than those in cold air, so they rise towards the ceiling.
73 exam-style questions on CIE IGCSE Physics 2.3.2 Convection. Each one has a worked solution and a mark scheme showing where the marks go.