Question detail
Chemical changes case 123 ph-precision. A student explains pH or neutralisation. Which option avoids vague wording? Focus on why carbon anodes are gradually used during aluminium in Using electrolysis to extract metals, 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 123 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for why carbon anodes are gradually used during aluminium
- B. Chemical changes case 123 ph-precision: Says strong acid means concentrated acid (Using electrolysis to extract metals)
- C. Chemical changes case 123 ph-precision: Says neutralisation only means the mixture becomes harmless (why carbon anodes are gradually used during aluminium)
- D. Chemical changes case 123 ph-precision: Uses pH numbers without linking them to acidity or alkalinity (Electrolysis)
Answer
The correct option is Chemical changes case 123 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for why carbon anodes are gradually used during aluminium.
Explanation
The correct option is Chemical changes case 123 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for why carbon anodes are gradually used during aluminium. It is correct because it directly supports the approved learning objective to explain why carbon anodes are gradually used up during aluminium extraction in Using electrolysis to extract metals. 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
Misunderstanding Anode Consumption
Students often think that carbon anodes are used up because they react with the aluminium being extracted, rather than understanding that they are consumed by reacting with oxygen produced during the electrolysis process.
Emphasize that carbon anodes are gradually used up due to the reaction with oxygen, forming carbon dioxide, rather than being consumed by the aluminium itself.
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