Identifying X and Y from Period 3 oxide properties

Steps:

• Period 3 elements include Na, Mg, Al, Si, P, S, Cl, Ar; amphoteric oxides are formed only by Al (Al₂O₃).
• Thus, Y = Al.
• X forms an oxide with +4 oxidation state: S qualifies (SO₂, S = +4); Si also +4 (SiO₂) but pairs with Y differently.
• Compound Z combines X = S and Y = Al as Al₂S.

Why B is correct:

• Al (Y) forms amphoteric Al₂O₃; S (X) has +4 oxidation state in SO₂, matching Al₂S formula.

Why the others are wrong:

• A: P (X) forms oxides with +5 (P₄O₁₀), not +4.
• C: P (Y) forms acidic oxide P₄O₁₀, not amphoteric.
• D: S (Y) forms acidic oxide SO₂/SO₃, not amphoteric.

Final answer: B