Identifying Period 3 elements by oxide reactivity patterns Steps: - Period 3 oxides range from basic (Na2O, MgO) to amphoteric (Al2O3) to acidic (SiO2, P4O10); match table to these behaviors. - Y's oxide reacts with H2O to form basic hydroxide (Mg(OH)2, "hydroxide acid" likely denotes solution properties), dissolves in HCl forming MgCl2, and interacts with NaCl to yield chloride salt via solubility. - X's oxide shows no reaction with H2O (Al2O3 insoluble), but hydrolyses in HCl (amphoteric reaction to AlCl3) and NaCl (partial hydrolysis). - Z's oxide hydrolyses in H2O and HCl, fitting SiO2 or P4O10 partial matches, confirming A assigns X=Al, Y=Mg correctly. Why A is correct: - Al2O3 and MgO align with table: Al2O3 inert in water but amphoteric hydrolysis in acids per Al2O3 + 6HCl → 2AlCl3 + 3H2O. Why the others are wrong: - B: Al oxide (Y) shows no water reaction, not "forms hydroxide acid." - C: Si oxide (X) inert in HCl, no hydrolysis; P oxide (Y) forms acid, not hydroxide. - D: Na oxide (Y) reacts vigorously with water, beyond "forms hydroxide acid"; …