What one characteristic of an atom determines what type of element it is?

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?

How many moles of bromine are needed to produce 3.23 moles of potassium bromide

Ab c or d ? i’m not sure what the answer is