Explain the acid-base behavior of silicon dioxide (SiO2) when it comes into contact with water. What is the expected pH of the solution?

Silicon dioxide (SiO2) does not react with water to form an acidic or basic solution. It is considered a neutral oxide and does not significantly affect the pH of water, which remains around 7. This answer is anchored to Period 3 oxides (A-level only).

Silicon dioxide (SiO2) does not react with water to form an acidic or basic solution. It is considered a neutral oxide and does not significantly affect the pH of water, which remains around 7. is the best answer because it directly supports the AQA A-Level Chemistry objective to explain acid-base behaviour of Period 3 oxides. This reasoning is anchored to Period 3 oxides (A-level only) in Properties of Period 3 elements and their oxides (A-level only), and it separates Period 3 oxide from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.