Which of the following statements best explains why convection currents form in a fluid when it is heated?
The fluid expands when heated, making it less dense than the surrounding cooler fluid.
The individual molecules of the fluid expand when heated, making them lighter.
The fluid contracts when heated, making it denser than the surrounding cooler fluid.
High-energy molecules escape from the surface of the fluid, pulling cooler molecules upward.
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.