What is exothermic and endothermic reaction ?​

Can someone me with questions 12 and 13 plz.

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

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?