Which two pairs are isotopes (W)with neutron 6 and proton 6
(x) with neutron 7 and proton 7
(y) with neutron 8 and proton 6
(z) with neutron 8 and proton 8

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.