How many sr2+ ions are in a mole of sr3(po4)2

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles.

1 mol  Sr3(PO4)2 ( 1 mol Sr2+ / 1 mol Sr3(PO4)2 ) ( 6.022x10^23 ions Sr2+ / 1 mol Sr2+ ) = 6.022x 10^23 Sr2+ ions

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.