Air above a radiator is heated and expands.
How does this thermal expansion lead to the formation of a convection current?
The density of the heated air decreases, causing it to rise.
The density of the heated air increases, causing it to rise.
The mass of the air molecules decreases, making them lighter.
The molecules themselves expand, increasing their individual volumes.
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.