Marking scheme
| Outcome | Marks |
|---|---|
| Correct answer | |
| Incorrect answer | |
| Left blank |
Thirty questions at four marks each gives a maximum of 120 marks.
With four options and exactly one correct, a blind guess is worth
so guessing at random gains a quarter of a mark on average — very slightly positive, not a penalty. That edge is far too small to be a plan. Eliminating options is what pays: a coin toss between two survivors is worth , six times as much. Leave an item blank only when every option still looks equally possible after a genuine attempt.
Time budget
| Block | Questions | Minutes each | Minutes |
|---|---|---|---|
| IUPAC nomenclature | 6 | 2.0 | 12 |
| Isomer counting and unsaturation | 4 | 2.5 | 10 |
| Stereochemistry | 4 | 2.0 | 8 |
| Intermediates and electronic effects | 5 | 1.5 | 7.5 |
| Resonance, aromaticity and Huckel | 4 | 1.5 | 6 |
| Reaction types and mechanisms | 3 | 1.5 | 4.5 |
| Purification and quantitative analysis | 4 | 3.0 | 12 |
| Total | 30 | 60 |
Sixty minutes for the set, timed in one sitting. Two minutes per question is the running average; the blocks differ because the work differs.
What the paper tests
Six items ask for a name under competing rules, so tracing every path through a skeleton and applying the tie-breaks in order carries the largest single share of the marks. Four ask for an exhaustive count, where the degree of unsaturation is the check that tells you when to stop; four more push that count into three dimensions with chirality, the cis-trans condition and the rule. The middle of the paper is stability reasoning — alpha-hydrogen counts, the intermediates and their shapes, and the cases where induction and resonance answer in opposite directions — followed by aromaticity, where the electron count and the position of a heteroatom lone pair settle everything. The two combustion items at the end are the longest on the paper at about three minutes each, because each one runs percentages, an empirical formula and then a molecular formula; the two hardest parent-chain names come next in length. Everything else should close inside two minutes, and five statement-based or assertion-reason items are scattered through the set to break the rhythm.
What you may use
- A printed periodic table.
- Rough paper and a pencil.
- No calculator. Every arithmetic step is designed to be done by hand, and the awkward-looking ratios cancel.
- No log tables. Nothing on this paper needs a logarithm, so none are provided.
- No molecular model kit. The stereochemistry items are meant to be settled on paper.