Chemical changes case 071 ph-precision. A student explains pH or neutralisation. Which option avoids vague wording? Focus on oxidation gain oxygen and reduction loss oxygen reactions in The reactivity series, not on a neighbouring Unit 4.4 reaction idea.

The correct option is Chemical changes case 071 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for oxidation gain oxygen and reduction loss oxygen reactions.

The correct option is Chemical changes case 071 ph-precision: Links pH or neutralisation to hydrogen ions, hydroxide ions or water formation for oxidation gain oxygen and reduction loss oxygen reactions. It is correct because it directly supports the approved learning objective to explain oxidation as gain of oxygen and reduction as loss of oxygen in reactions involving metal compounds in The reactivity series. 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.