As new seafloor is created in a rift valley, old seafloor is melted back into magma. which process accounts for this melting?

The process responsible for this is called sea floor spreading because of which magma pushes up and cools down to form new sea floor while while the old seafloor goes down via the process of subduction and melts to replenish the magma pool.

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass