When working with repelling magnets, potential energy can be stored when the
magnets are:
pulled apart (moved with the magnetic force)
pushed together (against the magnetic force)

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).

if you mean hydrogen and oxygen then water is the product