The short answer
Electrons changing hands — oxidation states, agents, and how a battery actually works.
Written and checked by GAMSAT tutors — not AI-generated.
Try the reasoning style
We treat forgetting as a failure — a lapse to be patched with reminders and records. Yet a mind that kept everything could not think; it would drown in the undifferentiated noise of every moment it had ever lived. To forget is not so much to lose information as to decide, mostly without our noticing, what was never worth keeping.
The author's argument relies most directly on which unstated assumption?
Pick an option to see how the tutor reasons to the answer — not just whether you were right.
Not quite — the answer is B.
Work backwards from the conclusion: a mind that ‘kept everything’ supposedly ‘could not think.’ That only follows if thinking means leaving most of experience out — so B is the premise the argument quietly rests on. A raises reliability, which the passage never weighs; C contradicts ‘mostly without our noticing’; D smuggles in a claim about intellect the passage never makes. The question rewards finding the hidden premise, not recalling a fact.
Every battery, every breath you take, and every rusting nail is the same chemistry: redox — reactions where electrons change hands. Get comfortable tracking those electrons and a whole class of Section III questions opens up.
OIL RIG
Oxidation Is Loss, Reduction Is Gain — of electrons. The two always happen together: one species loses electrons (oxidised), another gains them (reduced).
The name flip that catches everyone
The oxidising agent is the species that gets reduced (it takes the electrons). The reducing agent gets oxidised (it gives electrons away). The agent does the opposite of what its name sounds like — read it as "the thing that causes oxidation in others."
Oxidation vs reduction
Oxidation
- Loses electrons
- Oxidation state increases
- Happens at the anode
- The species is the reducing agent
Reduction
- Gains electrons
- Oxidation state decreases
- Happens at the cathode
- The species is the oxidising agent
Worked example
In the reaction , which species is oxidised, and which is the oxidising agent?
Check yourself
In a galvanic (voltaic) cell, oxidation occurs at the ___ and electrons flow through the wire toward the ___.
Key takeaways
- Redox = electron transfer; oxidation and reduction always occur together.
- OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).
- The oxidising agent is reduced; the reducing agent is oxidised.
- Track oxidation states to see who lost/gained electrons.
- Galvanic cell: oxidation at the anode, reduction at the cathode (An Ox, Red Cat).
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