A gas is heated, causing it to expand. How does this expansion lead to the formation of a convection current?
The density of the heated gas decreases, causing it to rise.
The density of the heated gas increases, causing it to sink.
The mass of the individual gas molecules decreases, making them lighter.
The thermal energy increases the mass of the gas molecules, forcing them upwards.
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.