The short answer
Recognising functional groups — the pattern-matching that makes organic Section III tractable.
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.
Organic chemistry in Section III is pattern recognition, not memorising hundreds of reactions. Spot the functional group and you can predict how a molecule behaves.
Why functional groups matter
A functional group is the reactive part of a molecule. The long carbon chain is mostly a spectator — the group decides the chemistry, the polarity, and the reactions.
The high-yield groups to recognise
Hydroxyl —OH (alcohols)
Polar, forms hydrogen bonds → higher boiling points and water solubility. Names end in -ol.
Carbonyl C=O (aldehydes & ketones)
A carbon double-bonded to oxygen. Aldehyde = on the end (—CHO); ketone = in the middle.
Carboxyl —COOH (carboxylic acids)
Carbonyl + hydroxyl together → acidic (donates H⁺). Names end in -oic acid.
Amine —NH₂ (amines)
Contains nitrogen → basic (accepts H⁺). The nitrogen analogue of an alcohol.
Reason from the group
Two molecules have the same carbon skeleton: one is an alcohol (—OH), the other an alkane (no functional group). Which has the higher boiling point, and why?
Check yourself
A molecule's name ends in '-oic acid'. Which functional group does it contain, and how will it behave?
Key takeaways
- The functional group, not the carbon chain, drives the chemistry.
- —OH (alcohol): polar, hydrogen-bonds, higher boiling point.
- —COOH (carboxylic acid): acidic; —NH₂ (amine): basic.
- Recognise the group, then reason — don't memorise reactions.
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