Question detail
Chemical changes case 117 ph-precision. A student explains pH or neutralisation. Which option avoids vague wording? Focus on that metal forms the cathode when molten ionic in Electrolysis of molten ionic compounds, 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
Electrolysis
Question
- A. Chemical changes case 117 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for that metal forms the cathode when molten ionic
- B. Chemical changes case 117 ph-precision: Says strong acid means concentrated acid (Electrolysis of molten ionic compounds)
- C. Chemical changes case 117 ph-precision: Says neutralisation only means the mixture becomes harmless (that metal forms the cathode when molten ionic)
- D. Chemical changes case 117 ph-precision: Uses pH numbers without linking them to acidity or alkalinity (Electrolysis)
Answer
The correct option is Chemical changes case 117 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for that metal forms the cathode when molten ionic.
Explanation
The correct option is Chemical changes case 117 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for that metal forms the cathode when molten ionic. It is correct because it directly supports the approved learning objective to predict that a metal forms at the cathode when a molten ionic compound is electrolysed in Electrolysis of molten ionic compounds. 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
Metal Formation at the Cathode
Students often think that a metal is always produced at the cathode, regardless of the ionic compound being electrolysed.
Students should remember that a metal forms at the cathode only when a molten ionic compound is electrolysed, and they should consider the specific ions present in the compound.
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