Trivia Difficulty Index
Per-topic wrong rates. Two editions: the July 21 league behind table 1, and the June 9 full file.
LearnClash open data
Hard Trivia Questions, Ranked by Real Miss Rates
Hard trivia questions, measured instead of guessed at. Every rate on this page comes from first-encounter answers in LearnClash 1v1 duels: 101,842 answers across 187 topics in the July 21, 2026 league, and 371 first answers behind the 8 selected question rows captured September 9. The two snapshots have different scopes and dates; they do not form a time trend. Sample size on every row.
The 50 hardest trivia topics by wrong rate
In the LearnClash Trivia Difficulty Index, a topic's wrong rate is the share of all recorded answers on that topic that were wrong. It is answer-weighted, so a question that 60 people met counts six times as much as one that 10 people met. The July 21, 2026 league ranks the 187 topics with at least 100 answers. These are the top 50, from Television (media) at 63.6% down to Advanced Physics (science) at 48.6%.
Where a topic has a question with 10 or more answers, its hardest one is listed under the topic name with that question's own wrong rate and sample. Those are anecdotes with small samples, not a ranking. Some topics have no question over the 10-answer line yet, so the cell stays empty rather than showing a number that wouldn't hold.
| # | Topic and its hardest question | Questions | Answers (n) | Wrong rate |
|---|---|---|---|---|
| 1 | Television (media) | 60 | 151 | 63.6% |
| 2 | Culture (anthropology)Hardest: In which country does nodding your head up and down mean no? (100.0% wrong, n=13) | 60 | 381 | 61.9% |
| 3 | Muscle Growth (biology)Hardest: Which amino acid primarily triggers the mTOR pathway for protein synthesis? (70.0% wrong, n=10) | 21 | 125 | 59.2% |
| 4 | Law (subject)Hardest: Which 1966 case required police to inform suspects of their rights? (100.0% wrong, n=10) | 35 | 246 | 58.5% |
| 5 | Pepe the Frog (meme)Hardest: What do Pepe the Frog and friends play a lot in Boy's Club comics? (81.8% wrong, n=11) | 51 | 295 | 58.0% |
| 6 | Numerology (mythology) | 34 | 111 | 57.7% |
| 7 | Colonization of Mars (space exploration) | 41 | 133 | 57.1% |
| 8 | Steve Jobs (businessperson) | 55 | 222 | 56.8% |
| 9 | Jellyfish (animal)Hardest: In which island nation is the famous stingless Jellyfish Lake located? (72.7% wrong, n=11) | 35 | 231 | 55.8% |
| 10 | Mars (planet)Hardest: Which NASA mission completed the first successful flyby of Mars in 1965? (92.3% wrong, n=13) | 82 | 575 | 55.0% |
| 11 | X-Men (comics)Hardest: Before joining the X-Men, what did African villagers worship Storm as? (18.2% wrong, n=11) | 34 | 130 | 54.6% |
| 12 | AC/DC (band)Hardest: Who is the lead guitarist of the rock band AC/DC? (33.3% wrong, n=12) | 57 | 218 | 54.6% |
| 13 | Seven Wonders of the Ancient World (history)Hardest: Which god was depicted by the tallest statue of the ancient world? (94.1% wrong, n=17) | 75 | 600 | 53.5% |
| 14 | Computer Hardware (technology)Hardest: What does SD stand for in SD card? (92.3% wrong, n=13) | 114 | 1,129 | 53.1% |
| 15 | Mechanical Engineering (science)Hardest: In fluid science, which noble gas has the highest boiling point? (90.0% wrong, n=10) | 363 | 1,375 | 52.9% |
| 16 | Movie (film)Hardest: In the film Parasite, what gift of wealth does Min-hyuk give the Kim family? (90.0% wrong, n=20) | 86 | 1,096 | 52.6% |
| 17 | Psychology (science)Hardest: Who is known as the "father of psychology" for opening the first lab? (92.3% wrong, n=13) | 99 | 642 | 52.5% |
| 18 | Disney Movies (film)Hardest: What does Peter Pan first try using to reattach his shadow? (90.0% wrong, n=10) | 29 | 122 | 52.5% |
| 19 | Famous Paintings (art) | 78 | 250 | 52.4% |
| 20 | Famous Quotes (literature)Hardest: What does Augustus Waters call a metaphor in The Fault in Our Stars? (82.4% wrong, n=17) | 25 | 236 | 52.1% |
| 21 | Janis Joplin (musician) | 46 | 104 | 51.9% |
| 22 | Feminism (ideology)Hardest: Which 19th-century feminist activist delivered the famous Ain't I a Woman? speech? (78.6% wrong, n=14) | 218 | 914 | 51.4% |
| 23 | James Dean (actor)Hardest: What Midwestern state did James Dean grow up on a farm in? (72.7% wrong, n=11) | 35 | 111 | 51.4% |
| 24 | Advanced Chemistry (science)Hardest: Which thermodynamic system allows exchange of both matter and energy? (90.0% wrong, n=10) | 145 | 606 | 51.0% |
| 25 | Artificial Intelligence (technology)Hardest: At which college was the conference held that launched artificial intelligence as a field? (100.0% wrong, n=10) | 77 | 769 | 51.0% |
| 26 | Medicine (science)Hardest: What painkiller originally came from chewing willow tree bark? (92.9% wrong, n=14) | 54 | 727 | 50.6% |
| 27 | Extraterrestrial Life (science)Hardest: What is the most numerous type of star in our galaxy? (70.0% wrong, n=10) | 33 | 188 | 50.5% |
| 28 | Brand Logos (design)Hardest: What do the four rings of the Audi logo represent? (76.5% wrong, n=17) | 90 | 976 | 50.4% |
| 29 | Information Technology (technology)Hardest: Who sent signals without wires using early radio technology? (95.5% wrong, n=22) | 54 | 550 | 50.4% |
| 30 | World War II (history)Hardest: What job did Queen Elizabeth II perform during World War II? (85.7% wrong, n=14) | 58 | 382 | 50.3% |
| 31 | Roman Gods (mythology)Hardest: Who guards the hearth fire in Roman homes? (90.5% wrong, n=21) | 62 | 883 | 50.2% |
| 32 | Donald Trump (politician)Hardest: Why did Donald Trump's parents send him to military school? (93.3% wrong, n=15) | 53 | 323 | 50.2% |
| 33 | Astronomy (science)Hardest: What percentage of stars in the sky are binary systems? (93.3% wrong, n=15) | 83 | 1,854 | 50.1% |
| 34 | Opera (art form) | 82 | 186 | 50.0% |
| 35 | Sociology (subject) | 54 | 142 | 50.0% |
| 36 | Rolex (watch brand)Hardest: Which Rolex model allows the wearer to track three different time zones simultaneously? (80.0% wrong, n=10) | 29 | 108 | 50.0% |
| 37 | Art (subject)Hardest: What color is the sky in Edvard Munch's painting The Scream? (70.0% wrong, n=10) | 86 | 301 | 49.8% |
| 38 | Celebrities (pop culture)Hardest: Why did Andy Warhol paint Marilyn Monroe many times? (93.8% wrong, n=16) | 86 | 718 | 49.7% |
| 39 | Porsche History (automobile manufacturer)Hardest: Which Sicilian road race inspired a Porsche model with a removable roof? (60.0% wrong, n=10) | 47 | 173 | 49.7% |
| 40 | Agatha Christie (author)Hardest: What record does Agatha Christie's play The Mousetrap hold in London theater? (50.0% wrong, n=14) | 237 | 690 | 49.7% |
| 41 | Buddhism (religion)Hardest: Which Japanese name is commonly used for the Bodhisattva of Compassion? (100.0% wrong, n=11) | 94 | 699 | 49.6% |
| 42 | Benjamin Franklin (statesman)Hardest: Why was Benjamin Franklin dismissed from his British postmaster role? (80.0% wrong, n=10) | 53 | 335 | 49.6% |
| 43 | Bridgerton (TV series)Hardest: Why did Colin Bridgerton go on a tour of Europe? (50.0% wrong, n=10) | 148 | 484 | 49.4% |
| 44 | The Quran (religious text) | 82 | 209 | 49.3% |
| 45 | Dad Jokes (humor) | 34 | 134 | 49.3% |
| 46 | Marriage Tips and Tricks (relationship advice)Hardest: What type describes most marital disagreements? (93.8% wrong, n=16) | 58 | 856 | 48.9% |
| 47 | God (mythology)Hardest: What did the Norse god Odin sacrifice by hanging on Yggdrasil for nine days? (100.0% wrong, n=12) | 54 | 339 | 48.7% |
| 48 | Perfume (novel) | 39 | 113 | 48.7% |
| 49 | Super Mario 64 (video game)Hardest: How many Power Stars unlock the final Bowser door in Super Mario 64? (94.4% wrong, n=18) | 38 | 411 | 48.7% |
| 50 | Advanced Physics (science)Hardest: Which isotope of hydrogen is the most common? (84.6% wrong, n=13) | 134 | 1,117 | 48.6% |
Full league of 187 topics in the July 21, 2026 CSV. The topic pages behind these rows are playable: pick any topic in the app and the duel draws from the same question pool.
Which selected questions had the lowest correct share?
This table ranks only the editorially selected September examples, each with at least 30 counted first-encounter answers. The lowest correct share in this small selection belongs to "Why do stars twinkle when viewed from Earth?": 9.7% correct across 31 first answers, with 25% as the model baseline for uniform guesses across four options. The 8 below run from 9.7% to 33.3% correct.
Read the rates as measured with the correct answer on screen. Every one of these was answered in a four-option duel round, so the player could recognize the answer instead of recalling it. Asked open-ended at a quiz night, the task changes. These data do not measure the size or direction of that change for each question. Ties on correct share are broken by the larger sample, then by file rank.
| # | Question | Correct answer | Correct | n | Topic |
|---|---|---|---|---|---|
| 1 | Why do stars twinkle when viewed from Earth? | Air turbulence bends their light rays | 9.7% | 31 | Astronomy (science) |
| 2 | Why is Pluto not considered a planet anymore? | It failed to clear its orbit | 20.0% | 30 | Astronomy (science) |
| 3 | Why do we see halos around the Moon sometimes? | Ice crystals refract moonlight | 22.6% | 31 | Astronomy (science) |
| 4 | Which insect is the strongest relative to its body weight? | Dung beetle | 24.6% | 61 | Animals (nature) |
| 5 | Who coined the scientific name 'Dinosauria' in 1842? | Richard Owen | 26.4% | 53 | Dinosaurs (paleontology) |
| 6 | What colors can dogs see besides black and white? | Yellow and blue | 29.7% | 64 | Animals (nature) |
| 7 | What does the Greek name for squirrel mean? | Shadow tail | 31.0% | 71 | Animals (nature) |
| 8 | What did Galileo see on Venus like the Moon? | phases | 33.3% | 30 | Astronomy (science) |
Which wrong answer those players picked instead, and the sources used to check these examples, are on the common misconceptions page. The separate hardest trivia questions bank uses historical examples, not this September selection.
Why these questions are hard
The LearnClash counts describe answers given with multiple-choice options on screen. Wrong options are selected from a larger distractor pool, so two encounters need not show the same choices. A concentrated wrong answer may reflect a familiar story, a knowledge gap or unclear wording. These aggregates cannot distinguish those causes or measure confidence. Before reusing a row, inspect the exact question and answer, its source and its sample size. The current question cut contains reviewed examples chosen from rows where one wrong option led. It is not a ranking of every question in the app; selection and small samples limit interpretation.
Methodology, floors, and downloads
Both datasets are read-only exports of the LearnClash production database. The files linked here are the bytes the tables were rendered from. This page is the canonical home; the Kaggle pages are mirrors of the June difficulty file and the July misconception file.
What a first-encounter answer is
The current counter contract records eligible first SRS encounters through the duel pipeline, excluding timeouts, information-assisted joker answers (50:50, Peek and Crowd) and web-play replays. Double Down remains eligible. Under the current write contract, human-side answers in AI-rival duels can contribute; standalone Solo does not write this question-level counter. Answer keys are content-version scoped, while first-encounter eligibility follows the separate meaning-change history. A content-version change does not necessarily reset that history. This source review describes today's contract, not verified enforcement for every event in the historical files.
The topic league sums recognized answer counts across content versions. The Misconception Index selects current-version counts and excludes rows whose version had to be inferred. The export dates are capture dates for cumulative counts, not observation windows. Per-answer dates, confidence, language-specific groups, option impressions and distinct people across rows are not available. These snapshots cannot establish a time trend or a population estimate; the sample consists of recorded LearnClash app answers; distinct people cannot be counted.
Topic league (table 1)
- Source: 187 topics with at least 100 answers in the LearnClash league of 2026-07-21, 101,842 answers in total. The wrong rate is answer-weighted: wrong answers divided by all answers on the topic.
- Floor: 100 answers per topic; the hardest-question annotation needs 10 answers on that question and is shown with its own n.
- The June 9, 2026 file is the first public edition: all 570 topics, 80,553 answers, overall wrong rate 43.5%, 156 topics flagged qualified_for_league. It is the version mirrored on Kaggle.
Hardest questions (table 2)
- Source: the LearnClash Misconception Index, captured 2026-09-09. The scan read 968 public topic records and hit its 40,000-question cap after 21 of 33 topic-query batches. Of 495 machine-eligible rows, 16 had a wrong option leading; 8 survived editorial review. These selected rows contain 371 counted first-encounter answers.
- Floor: 30 first-encounter answers per question. The September cut excludes ambiguous or unsupported questions and retains exact wording and counters. The curation record documents inclusions and exclusions.
- Ranking: lowest correct share first. This ranks only the selected examples. Small samples make rankings unstable. The sample column gives context; a fixed margin rule cannot establish which questions differ reliably.
Licence and citation
CC BY 4.0. Cite as "LearnClash Trivia Difficulty Index, July 2026, Pluxia GmbH (learnclash.com)" or "LearnClash Misconception Index, September 9, 2026 curated sample, Pluxia GmbH (learnclash.com)", with a link to this page. Aggregates only; neither file contains user-level records.
Misconception Index
Per-question first-encounter shares with the most-picked wrong answer and a p-value per row.
Questions, corrections, or a request for a cut this page doesn't show: admin@learnclash.com. Press facts and logos are on the press page.
Try the hardest topics in a duel
LearnClash is 1v1 trivia on any topic, with a skill-matched opponent and a fact after every answer. The questions above come from the same pool your duels draw from. Free on iOS and Android, in English, German, French and Spanish.
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