CBSE Class 10 Science Important Chapters 2027 (From Board Papers)
Most important chapters for CBSE Class 10 Science boards 2027, with marks per chapter from 8 real board papers (2023–2026) and which chapters repeat. Free…
Short answer: in recent CBSE Class 10 Science board papers, the chapters carrying the most marks are Light – Reflection & Refraction (about 11.2 marks per paper), Electricity (about 9.0 marks per paper), Carbon & its Compounds (about 7.2 marks per paper). Together these three make up about 36% of the chapter-tagged marks in the 80-mark theory paper. The table below is calculated from 8 real CBSE board papers (2023–2026), not guessed.
Chapter-wise weightage: Class 10 Science
| # | Chapter | Avg marks per paper | Share |
|---|---|---|---|
| 1 | Light – Reflection & Refraction | 11.2 | 15% |
| 2 | Electricity | 9.0 | 12% |
| 3 | Carbon & its Compounds | 7.2 | 10% |
| 4 | Acids, Bases & Salts | 6.5 | 9% |
| 5 | Life Processes | 6.1 | 8% |
| 6 | How do Organisms Reproduce | 6.0 | 8% |
| 7 | Metals & Non-metals | 5.0 | 7% |
| 8 | Chemical Reactions & Equations | 4.4 | 6% |
| 9 | Heredity | 4.4 | 6% |
| 10 | Magnetic Effects of Current | 4.4 | 6% |
| 11 | Human Eye & Colourful World | 4.1 | 5% |
| 12 | Our Environment | 3.8 | 5% |
| 13 | Control & Coordination | 3.2 | 4% |
Method: each question in the 2023–2026 board papers (two sets per year) is tagged to its NCERT chapter. Marks are added up per paper and averaged. Tagging is automated, so treat each figure as roughly ±1 mark. Full methodology.
Which chapters to revise first
Must-do: about 10% of the paper or more each
Light – Reflection & Refraction, Electricity. Revise these first and solve every previous year question on them.
High value: 5–10% each
Carbon & its Compounds, Acids, Bases & Salts, Life Processes, How do Organisms Reproduce, Metals & Non-metals, Chemical Reactions & Equations, Heredity, Magnetic Effects of Current, Human Eye & Colourful World. Cover these thoroughly after the must-do chapters.
Lower weightage: under 5% each
Our Environment, Control & Coordination. Don't skip them: they still add up and often carry quick one-mark questions.
Do questions repeat in Class 10 Science?
Comparing all 339 Class 10 Science board questions from 2022–2026, 3 were asked again, in near-identical form, in a different board year, most often from Light – Reflection & Refraction. Exact repeats are rare here, so focus on understanding concepts rather than memorising old answers.
The most repeated questions, with the years they appeared, are listed on the CBSE Class 10 Science previous year papers page.
192 CBSE board papers split into single questions with official answers, chapter-wise practice and unlimited mock papers. 100% free: no ads, no paid plan, no hidden charges.
How to use this list
- Start with the must-do chapters. Read the NCERT chapter, then solve its previous year board questions and check them against the marking scheme.
- Don't drop any chapter. Weightage is an average: any chapter can carry a long question in your paper.
- Finish with full papers. In the last 6 weeks, take full timed board-pattern papers. BoardPrep's free mock generator makes a new one each time, with an answer key.