Which of the following oxides, when dissolved in water, will produce a solution with a pH greater than 7?
Show the answer and explanation
Correct answer
C. Na2O
Principle or equation
Metal oxides are basic oxides; they react with water to form bases, producing basic solutions (pH > 7). Non-metal oxides are acidic oxides; they form acids in water, producing acidic solutions (pH < 7).
Why this answer is correct
Na2O is a metal oxide. It reacts with water to form sodium hydroxide, a strong base, so the solution is basic (pH > 7). SO2, CO2, and P2O5 are non-metal oxides that produce acidic solutions.
Example
Na2O(s) + H2O(l) → 2NaOH(aq). The resulting solution has a pH greater than 7.
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