How often do CBSE Class 10 board questions actually repeat?
We mapped every question in years of official CBSE Class 10 board papers — all sets — to the concept it tests. The short answer: in recent board exams, roughly 4 out of 5 Science and Social Science concepts had already appeared in earlier years’ papers. In the 2025 papers, the concept repeat rate was 81% in Science and 79% in Social Science. English sits lower (~58%) because its reading and writing sections change texts each year even when the question formats stay fixed.
“Repeat” here means the same tested concept — not identical wording or numbers. Every number on this page comes from the open dataset at the bottom; the methodology and its limits are spelled out there too.
Concept repeat rate by year
Share of each year’s exam concepts that had appeared in at least one earlier year of the paper corpus.
| Subject | Year | Questions analysed | Concepts tested | Repeat rate |
|---|---|---|---|---|
| English | 2019 | 160 | 36 | 61% |
| English | 2020 | 43 | 21 | 24% |
| English | 2022 | 32 | 8 | 100% |
| English | 2023 | 98 | 28 | 46% |
| English | 2024 | 124 | 36 | 53% |
| English | 2025 | 125 | 33 | 58% |
| Science | 2019 | 173 | 55 | 56% |
| Science | 2020 | 148 | 50 | 58% |
| Science | 2023 | 242 | 57 | 79% |
| Science | 2024 | 232 | 58 | 79% |
| Science | 2025 | 245 | 58 | 81% |
| Social Science | 2019 | 117 | 30 | 80% |
| Social Science | 2020 | 233 | 50 | 82% |
| Social Science | 2022 | 64 | 25 | 56% |
| Social Science | 2023 | 197 | 54 | 74% |
| Social Science | 2024 | 215 | 45 | 80% |
| Social Science | 2025 | 248 | 56 | 79% |
Years where a subject’s corpus was too thin to measure repeats meaningfully are omitted; 2026 is excluded as partial. Mathematics is analysed separately below — see the methodology note.
Practice exactly these repeating concepts
This analysis powers ClearSteps’ chapter-wise PYQ practice — the same corpus, organised so you drill the concepts with the highest repeat probability first.
Mathematics: the question types that keep coming back
For Maths we cluster questions into archetypes — our own descriptions of the question type. These are the archetypes that appeared in the most exam years:
| Question archetype | Years appeared | Which years |
|---|---|---|
| Prove: parallelogram circumscribing a circle is a rhombus | 4 of 6 | 2020, 2022, 2023, 2024 |
| Find HCF and LCM of two or three numbers using prime factorisation | 3 of 5 | 2023, 2024, 2025 |
| Find LCM of numbers expressed as products of prime factors (in index form) | 3 of 5 | 2023, 2024, 2025 |
| Bell/clock tolling together — find time using LCM | 3 of 5 | 2023, 2024, 2025 |
| Find HCF of given concrete numbers (direct computation) | 3 of 5 | 2020, 2024, 2025 |
| Find LCM given HCF, using the product property HCF × LCM = product of numbers | 3 of 5 | 2020, 2023, 2024 |
| Find unknown exponent x in prime factorisation given LCM | 3 of 5 | 2024, 2025, 2026 |
| Compute HCF × LCM product for two given numbers | 3 of 5 | 2023, 2024, 2025 |
| Prove: tan θ/(1–cot θ) + cot θ/(1–tan θ) = 1 + sec θ cosec θ | 2 of 5 | 2023, 2024 |
| Simplify ratio/expression involving tan²A and cot²A to simplest form | 2 of 5 | 2020, 2023 |
| Prove: (sin³A – 2sinA)/(2cosA – cos³A) = tan A | 2 of 5 | 2023, 2024 |
| Find HCF of two numbers given their ratio and LCM (or vice versa) | 2 of 5 | 2023, 2025 |
The standout: the “prove a parallelogram circumscribing a circle is a rhombus” proof appeared in 4 of the 6 corpus years. Real Numbers (HCF/LCM) archetypes appeared in 3 consecutive years, 2023–2025.
Chapter-wise: where the repeated marks live
Science
| Chapter | Concepts tracked | Total appearances | Avg marks / question |
|---|---|---|---|
| Metals and Non-metals | 6 | 131 | 2.5 |
| Life Processes | 6 | 130 | 2.2 |
| Chemical Reactions and Equations | 6 | 127 | 2.0 |
| Light - Reflection and Refraction | 5 | 126 | 2.6 |
| Electricity | 6 | 113 | 2.7 |
| Our Environment | 5 | 104 | 1.8 |
| How do Organisms Reproduce? | 5 | 103 | 2.4 |
| Carbon and its Compounds | 6 | 90 | 2.8 |
Social Science
| Chapter | Concepts tracked | Total appearances | Avg marks / question |
|---|---|---|---|
| Sectors of the Indian Economy | 3 | 84 | 2.0 |
| The Rise of Nationalism in Europe | 3 | 79 | 2.3 |
| Print Culture and the Modern World | 2 | 74 | 2.0 |
| Money and Credit | 3 | 72 | 2.0 |
| Political Parties | 3 | 67 | 2.3 |
| Development | 3 | 66 | 1.3 |
| Globalisation and the Indian Economy | 3 | 64 | 3.0 |
| Gender, Religion and Caste | 3 | 60 | 2.0 |
English
| Chapter | Concepts tracked | Total appearances | Avg marks / question |
|---|---|---|---|
| Reading Comprehension | 8 | 123 | 8.4 |
| Writing Skills | 4 | 117 | 7.8 |
| Grammar | 12 | 87 | 4.5 |
| First Flight — Prose | 6 | 82 | 6.8 |
| First Flight — Poetry | 6 | 41 | 5.2 |
| Writing Skills — Long Compositions | 4 | 38 | 8.8 |
| Footprints Without Feet | 4 | 28 | 6.3 |
| Literature Reader — Prose | 3 | 22 | 7.7 |
The individual concepts that appear most
Science
- Ohm's law and V-I characteristics — in 74% of papers analysed
- Asexual reproduction (fission, budding, vegetative) — in 77% of papers analysed
- Physical and chemical properties of metals vs non-metals — in 74% of papers analysed
- Mirror formula and magnification — in 71% of papers analysed
- Combination reactions — in 41% of papers analysed
Social Science
- Democracy and social outcomes (dignity, freedom) — in 81% of papers analysed
- Pre-modern world and trade routes — in 77% of papers analysed
- History of print technology — in 61% of papers analysed
- Formal vs informal sources of credit — in 84% of papers analysed
- Primary, secondary and tertiary sectors — in 65% of papers analysed
English
- Analytical paragraph (data/process/situation) — in 97% of papers analysed
- Formal letter writing — in 90% of papers analysed
- Factual passage MCQ (multiple choice) — in 97% of papers analysed
- Inference-based short answer questions — in 57% of papers analysed
- From the Diary of Anne Frank: character analysis — in 47% of papers analysed
Methodology, limits, and the open dataset
- Source: official CBSE Class 10 board papers (all available sets per year) in the ClearSteps corpus.
- Every question is mapped to the concept it tests; concepts map to NCERT chapters.
- A concept counts as repeated in a year if it appeared in any earlier corpus year — so the earliest years are baselines, not low-repeat years.
- Mathematics concept-level rollups are excluded on purpose: our verification found Class 11/12 concepts mixed into that subject’s aggregate, so Maths is represented only by question archetypes individually verified as Class 10 content. We publish what survives verification, not everything we computed.
- Repeat rate measures the tested idea, not verbatim wording — CBSE varies numbers, contexts, and phrasing.
- No CBSE question text is reproduced here or in the dataset; archetype labels are our own analytical descriptions.
Free to reuse with attribution to ClearSteps. Journalists and researchers: the dataset includes per-year sample sizes so you can judge robustness yourself.