Which statement about convection in fluids is correct?
Convection currents can only occur in liquids.
When a fluid is heated, it expands, becomes less dense, and rises.
When a fluid is cooled, it contracts, becomes less dense, and sinks.
Convection currents occur in solids when particles vibrate about fixed positions.
301 exam-style questions on CIE IGCSE Physics 2.3 Transfer of thermal energy, covering 2.3.1a Thermal conductors and thermal insulators, 2.3.1b Explaining thermal conduction, 2.3.2 Convection, 2.3.3a Thermal radiation, 2.3.3b Surface colour and texture, 2.3.3c Rate of emission and absorption of radiation, and 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.