Compare and contrast the two upper layers of the mantle.

In an oxidation-reduction reaction, oxidation is what happens when a reactant

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?

Which fact represents evidence for the big bang theory?