Period 3 oxides form acidic or basic solutions with water based on metallic/non-metallic character Steps:

• Basic oxides from left-side elements (e.g., Na) react with water to form alkaline solutions containing OH⁻.
• Acidic oxides from right-side elements (e.g., Si) react with water to form acidic solutions containing H⁺.
• Both oxides must react to produce colourless solutions, one alkaline and one acidic.
• Evaluate options to find the pair matching these criteria.

Why C is correct:

• Na₂O + H₂O → 2NaOH (alkaline colourless solution); SiO₂ + 2H₂O → H₄SiO₄ (weak acidic colourless solution).

Why the others are wrong:

• A: Al₂O₃ and SiO₂ are both insoluble in water, forming no solutions.
• B: Al₂O₃ is insoluble in water and forms no solution.
• D: P₄O₁₀ reaction with water is violent and exothermic, not forming a simple colourless solution.

Final answer: C