solution element (x) Atomic No-12 (Magnesium) element (y) - Atomic No - 8 (oxygen) element (Z) - Atomic NO - 17 (Chlorine) The Formula when x & y combine Mg + O → MgO The Compound of x and y Magnesium oxide (Mgo) The Chemical formula of the Compond when X and Z Combine Mg + 2Cl → MgCl₂(magnesium. Chloride) Hence the compounds are Mgo MgCl₂