What happens to the density of a fluid when its heated?

The agent of mechanical weathering in which rock is worn away by the grinding action of other rock particles is call

Calculate the number of molecules present in 0.750 mol of mgo.

Which process does not require the presence of a physical substance in order to transfer heat? air in the atmosphere is heated by the ground. this warm air then rises, and cooler air falls. this is an example of what type of process? how is conduction different from radiation?