Matching Period 3 elements to oxide properties Steps:

• Period 3 elements include Na, Mg, Al, Si, P, S, Cl, Ar; Y forms amphoteric oxide, so Y = Al (Al2O3).
• X has +4 oxidation number in its oxide; possible elements are Si (SiO2) or S (SO2).
• Compound Z forms from X and Y; choices with Al (Y) are A and B.
• Eliminate A (AlP): P oxide is P4O10 with +5 oxidation state, not +4 for X; B (Al2S) fits X = S with +4 in SO2.

Why B is correct:

• Al2S combines Al (amphoteric Al2O3) and S (+4 oxidation in SO2), matching the conditions.

Why the others are wrong:

• A: P has +5 in its oxide (P4O10), not +4 for X.
• C: P oxide (P4O10) is acidic, not amphoteric for Y.
• D: S oxide (SO2) is acidic, not amphoteric for Y.

Final answer: B