Question

11 convection happens only in fluids, which are substances that flow and do not have a definite shape. why is that? a in convection, the bulk movement of matter occurs as it warms becomes less dense and rises, cools and becomes more dense and sinks. b in convection, matter is not required for heat transfer so solids get in the way. c in convection, the particles bump against each other to transfer energy and this is more easily done in fluids. d in convection, the cooler particles rise closer to the sun to gain thermal energy and the hotter particles sink.

Explanation:

Convection involves the bulk - movement of matter. In fluids, when heated, matter becomes less dense and rises, and when cooled, it becomes more dense and sinks. This bulk - movement is not possible in solids as they have a fixed shape. Option A correctly describes the process of convection and why it occurs in fluids. Option B is incorrect because matter is required for convection. Option C describes conduction (particle - to - particle energy transfer), not convection. Option D has an incorrect description of the movement of particles in convection (hotter particles rise, cooler ones sink).

Answer:

A. In convection, the bulk movement of matter occurs as it warms becomes less dense and rises, cools and becomes more dense and sinks.