Question detail
Chemical changes case 001 acid-base-boundary. A student sorts acid, alkali and base statements. Which option keeps the terms distinct? Focus on neutralisation terms hydrogen ions reacting with hydroxide ions in The pH scale and neutralisation, not on a neighbouring Unit 4.4 reaction idea.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Reactions of acids
Question
- A. Chemical changes case 001 acid-base-boundary: Keeps the acid-base distinction tied to the named substance for neutralisation terms hydrogen ions reacting with hydroxide ions
- B. Chemical changes case 001 acid-base-boundary: Treats every base as an alkali without checking solubility (The pH scale and neutralisation)
- C. Chemical changes case 001 acid-base-boundary: Uses pH wording but does not identify the acid-base role (neutralisation terms hydrogen ions reacting with hydroxide ions)
- D. Chemical changes case 001 acid-base-boundary: Names a salt product without explaining the reaction context (Reactions of acids)
Answer
The correct option is Chemical changes case 001 acid-base-boundary: Keeps the acid-base distinction tied to the named substance for neutralisation terms hydrogen ions reacting with hydroxide ions.
Explanation
The correct option is Chemical changes case 001 acid-base-boundary: Keeps the acid-base distinction tied to the named substance for neutralisation terms hydrogen ions reacting with hydroxide ions. It is correct because it directly supports the approved learning objective to describe neutralisation in terms of hydrogen ions reacting with hydroxide ions to produce water in The pH scale and neutralisation. The other options are incorrect because they blur a Unit 4.4 concept boundary: acid versus alkali versus base, oxidation versus reduction, displacement versus reduction, electrolysis versus electroplating, anode versus cathode, positive versus negative ions, oxidation state versus ionic charge, or strong acid versus concentrated acid.
Common mistake
Confusing ionic and molecular equations
Students write the neutralisation reaction as H⁺ + OH⁻ → H₂O instead of the full ionic equation H⁺(aq) + OH⁻(aq) → H₂O(l) and omit the state symbols, or they write a molecular equation such as HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l) and then claim it is the ionic equation.
Remind students that the ionic equation shows only the ions that actually participate in the reaction. The correct ionic equation for neutralisation is H⁺(aq) + OH⁻(aq) → H₂O(l). The molecular equation is fine for describing the overall reaction, but the ionic form is required when describing the mechanism of neutralisation.
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