USNCO Past Papers & Solutions
US National Chemistry Olympiad
USNCO local and national exam past papers with answer keys and worked solutions covering the full ACS syllabus.
- Eligibility
- US high-school students
- Format
- Local exam: 60 multiple-choice · National exam: multiple-choice, free-response and a lab practical
- Duration
- Local: 110 minutes · National: three parts across the day
- Scoring
- Section scores combined; top performers invited to the study camp
USNCO runs in stages: a local multiple-choice exam that most students take at school, a national exam with written and practical components, and a study camp that selects the US IChO team. The local exam rewards broad, fast recall and clean stoichiometry; the national exam rewards depth. Because the ACS publishes past exams with answer keys going back many years, past-paper practice is unusually effective here — the topic distribution barely moves between years.
Past papers by year
Each year page lists the official paper source (paper Local and paper National), the answer key location, difficulty notes and how to review your solutions.
Stuck on a USNCO question?
Send us the question number. A mentor who has sat and medalled in USNCO will reply with a step-by-step walkthrough and the faster competition method.
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What the paper tests
Stoichiometry
Thermodynamics
Kinetics & equilibrium
Electrochemistry
Organic & structure
Laboratory practice
Where it leads: National exam top scorers are invited to the USNCO study camp and IChO team selection. See our coaching programme.
Book personalised USNCO classes
Past papers show you the gap; a mentor closes it. Our USNCO mentors are medal winners who walk through every solution 1-to-1, then set targeted practice on the archetypes you lost marks on.
Want the full USNCO paper pack and score guide?
Tell us your target and we will send the USNCO paper list, the official scoring rules and a preparation plan built around the questions you keep losing marks on.
Free to ask. No spam, ever — we only reply about your question.
Frequently asked questions
- Where can I get USNCO past exams?
- The American Chemical Society publishes past local and national exams with answer keys on its Chemistry Olympiad pages. We link there and add worked explanations for the questions students most often miss.
- How should I use the local exam archive?
- Sit them timed, 60 questions in 110 minutes, and log every miss by topic. After four papers the pattern is usually obvious and revision becomes targeted rather than general.