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CBSE Class 10 Science syllabus 2026-27: units, marks, chapters and what is not examined
This guide sets out what the CBSE Class 10 Science (subject code 086) syllabus for 2026-27 actually contains, taken straight from CBSE's own curriculum document and the NCERT textbook. It covers the five units and their marks, the 13 NCERT chapters, the topics CBSE says will not be examined in the board paper, the practical work, and how the 80-mark paper is laid out. Every number names its document and page, listed at the end. Page numbers are PDF pages.
The official curriculum is a 9-page PDF on cbseacademic.nic.in: CBSE Science curriculum, Class X, 2026-27.
The marks at a glance
The year-end (board) theory paper is 3 hours and 80 marks; internal assessment at school adds 20 marks, for a total of 100 (curriculum, page 4).
| Unit | Name in the curriculum | Theory marks |
|---|---|---|
| I | Chemical Substances: Nature and Behaviour | 25 |
| II | World of Living | 25 |
| III | Natural Phenomena | 12 |
| IV | Effects of Current | 13 |
| V | Natural Resources | 5 |
| Total | 80 |
Source: curriculum, page 4 ("Course structure, Class X (2026-27)").
Units I and II (chemistry, and biology apart from the environment chapter) carry 50 of the 80 theory marks; the two physics units, III and IV, carry 25; Unit V, the environment, carries 5.
The 13 NCERT chapters, unit by unit
The prescribed textbook is NCERT's Science, Textbook for Class X (curriculum, page 8). The current edition (Reprint 2026-27) has 13 chapters (NCERT contents page, PDF page 11). The curriculum does not number chapters; we have placed each chapter under the unit whose topics it covers.
| Unit | NCERT chapters (chapter number, title, start page in the book) |
|---|---|
| I Chemical Substances (25) | 1 Chemical Reactions and Equations (p. 1); 2 Acids, Bases and Salts (p. 17); 3 Metals and Non-metals (p. 37); 4 Carbon and its Compounds (p. 58) |
| II World of Living (25) | 5 Life Processes (p. 79); 6 Control and Coordination (p. 100); 7 How do Organisms Reproduce? (p. 113); 8 Heredity (p. 128) |
| III Natural Phenomena (12) | 9 Light: Reflection and Refraction (p. 134); 10 The Human Eye and the Colourful World (p. 161) |
| IV Effects of Current (13) | 11 Electricity (p. 171); 12 Magnetic Effects of Electric Current (p. 195) |
| V Natural Resources (5) | 13 Our Environment (p. 208) |
What each unit covers
These are the topics the curriculum lists (pages 4 to 6), in brief.
- Unit I, Chemical Substances. Chemical reactions and balanced equations, and the types of reaction (combination, decomposition, displacement, double displacement, precipitation, endothermic and exothermic, oxidation and reduction). Acids, bases and salts, including indicators, neutralisation, the pH scale, and how baking soda, washing soda, bleaching powder, plaster of Paris and sodium hydroxide are made and used. Metals and non-metals, the reactivity series, ionic compounds, basic metallurgy and corrosion. Carbon compounds: covalent bonds, the versatile nature of carbon, homologous series, naming, chemical properties, ethanol and ethanoic acid (properties and uses only), soaps and detergents.
- Unit II, World of Living. How plants and animals get nutrition, respire, move materials around and remove wastes. Control and coordination: tropic movements and plant hormones; the nervous system; voluntary, involuntary and reflex action; animal hormones. Reproduction in plants and animals, reproductive health and family planning. Heredity: Mendel's contribution and laws of inheritance, with a brief introduction to sex determination.
- Unit III, Natural Phenomena. Reflection by spherical mirrors and the mirror formula, refraction and refractive index, spherical lenses and the lens formula, magnification and the power of a lens. The human eye, defects of vision and their correction, refraction through a prism, dispersion and scattering of light.
- Unit IV, Effects of Current. Electric current and potential difference, Ohm's law, resistance and resistivity, resistors in series and in parallel, the heating effect of current, electric power and how P, V, I and R are linked. Magnetic effects: magnetic field and field lines, the field of a straight conductor, a coil and a solenoid, the force on a current-carrying conductor and Fleming's left-hand rule, direct and alternating current, and domestic circuits.
- Unit V, Natural Resources. Our environment: ecosystems, environmental problems, ozone depletion, waste and its solutions, and biodegradable and non-biodegradable substances.
What is not in the board paper
The unit lists in the curriculum name these topics; the Note for Teachers on the same page is worded more widely (see "One line to read with care" below). The curriculum does not list any chapter as deleted or added for 2026-27.
Taught, but assessed only at school ("formatively"), not in the board paper:
- Periodic Classification of Elements: Döbereiner's triads, Newlands' octaves, Mendeléev's table and the modern periodic table (page 4).
- The evolution topics: acquired and inherited traits, speciation, fossils, evolution and classification, tracing evolutionary relationships, evolution by stages and human evolution (page 5).
- The electric motor, electromagnetic induction and the electric generator (page 6).
The current NCERT book has no chapter on periodic classification or on evolution; the curriculum says the relevant NCERT material is enclosed with it for reference (pages 4-6).
Left out of what is examined, inside topics that are examined:
- Information in the boxes of the NCERT textbook is not assessed in the year-end exam (page 6, note 3).
- Why the sun looks reddish at dawn and dusk is excluded (page 6).
- The derivations of the mirror formula and the lens formula are not required (page 5).
- The definition of pH in terms of logarithms is not required (page 4).
- For ethanol and ethanoic acid, only their properties and uses (page 5).
One line to read with care. The curriculum's "Note for Teachers" (page 6) says: "The topics Periodic Classification of Elements; Heredity and Evolution; and Electric Effects of Electric Current will not be assessed in the year-end examination." It adds that learners may be asked to read these topics and write a brief note for their Portfolio, which can earn Periodic Assessment or Portfolio credit. The note's names are wider than the unit lists on pages 4 to 6, which keep Heredity (Mendel's laws) and the magnetic effects of current, and mark only Periodic Classification, the Evolution topics, and the motor, electromagnetic induction and generator as formative only. The 2026-27 sample paper also asks Mendel's crosses (Q15, 4 marks) and the magnetic field of a current (Q36, Q38). Our reading, not CBSE's, is that the note is shorthand for those three formative-only blocks. Until CBSE clarifies, prepare heredity and the magnetic effects, and ask your teacher how your school reads the note.
Internal assessment: the other 20 marks
The curriculum splits the 20 school marks into four parts of 5 each (page 9):
| Part | Marks |
|---|---|
| Periodic assessment | 5 |
| Multiple assessment | 5 |
| Portfolio | 5 |
| Subject enrichment (practical work) | 5 |
| Total | 20 |
The curriculum lists 14 practical experiments, done alongside the theory (pages 7-8). Among them:
- the pH of everyday samples;
- reaction types;
- a reactivity order of four metals;
- Ohm's law and resistors in series and parallel;
- a stomata leaf peel;
- carbon dioxide in respiration;
- acetic acid;
- soap in hard and soft water;
- focal lengths;
- the glass slab and the prism;
- fission and budding slides;
- the parts of a dicot embryo.
The prescribed books also include the NCERT Laboratory Manual, NCERT Exemplar Problems, CBSE's Assessment of Practical Skills in Science and CBSE's Reading Material for 2026-27 (page 8).
How the 80-mark paper is built
The curriculum's question paper design (page 9) splits the theory marks by skill, and the 2026-27 sample paper shows the layout.
- By skill: 50% knowledge and understanding, 30% applying knowledge, 20% analysing, evaluating and creating. Internal choice of about 33% (curriculum, page 9).
- Question types: very short answer and objective questions, assertion-reason, short answer, long answer, and source-based, case-based or passage-based questions (curriculum, page 9).
- The sample paper has 39 questions in three sections: Section A Biology, Section B Chemistry, Section C Physics (sample paper, page 1). Section A carries 30 marks (Q1-Q16), Section B 25 (Q17-Q29) and Section C 25 (Q30-Q39), which matches the unit marks above: Biology is Units II and V (25 + 5), Chemistry is Unit I, Physics is Units III and IV (12 + 13).
- Across the sample paper there are 20 one-mark questions (4 of them assertion-reason), 6 two-mark, 7 three-mark, 3 four-mark and 3 five-mark questions.
Our section-by-section guide to the 2026-27 Science sample paper goes through each question type and how the marking scheme gives marks.
FAQ
How many chapters are there in Class 10 Science for 2026-27? The NCERT textbook (Reprint 2026-27) has 13 chapters, from Chemical Reactions and Equations to Our Environment (NCERT contents, PDF page 11).
How many marks is the Class 10 Science board paper? 80 marks in 3 hours, plus 20 marks of internal assessment at school, 100 in all (curriculum, page 4).
Is the Periodic Table in the Class 10 board exam? No. Periodic Classification of Elements is taught but assessed only at school, not in the board paper (curriculum, page 4).
Is Heredity in the 2026-27 board exam? Unit II lists heredity and Mendel's laws as part of the syllabus (curriculum, page 5) and the sample paper asks them (Q15). The evolution topics are assessed only at school. The teachers' note on page 6 is worded more widely, so check with your teacher.
Has any chapter been deleted for 2026-27? The curriculum does not list deleted chapters. It names topics that will not be examined in the board paper; they are listed above.
Practise
- Timed: the free Class 10 revision papers include two Science papers, marked in your browser (shorter than the real paper; our own questions, still waiting for teacher review).
- Chapter by chapter: the Class 10 worksheets and the practice page (pick Class 10), in English, Hindi and Marathi.
- Chapter guides: Chemical Reactions and Equations and Electricity.
- Practice questions with answers, chapter by chapter: Life Processes, Acids, Bases and Salts, Metals and Non-metals, Carbon and its Compounds and Light: Reflection and Refraction.
Where CMDLearn fits
CMDLearn is building an AI tutor for Classes 1 to 10 that explains a step and checks the child's working, but leaves the writing to the child. It is still in development, and no child uses it yet. If you would like to hear when there is something to try, you can join the waitlist.
Sources
All opened and read on 21 October 2026. Page numbers are PDF pages.
- CBSE, Science (Subject Code 086), Class X (2026-27), curriculum: page 4 (course structure, unit marks, Unit I, periodic classification formative, pH logarithm not required), page 5 (Units I-III topics, evolution formative, mirror and lens derivations not required), page 6 (Units III-V, motor and generator formative, sunrise/sunset excluded, note for teachers, boxed text), pages 7-8 (practicals, prescribed books), page 9 (question paper design, internal assessment). cbseacademic.nic.in/web_material/CurriculumMain27/SecPart1/Science_SecP1_2026-27.pdf
- CBSE, Science (086) Sample Question Paper, Class X, 2026-27: page 1 (39 questions, three sections), pages 1-15 (question marks; Q15, Q36, Q38). cbseacademic.nic.in/web_material/SQP/ClassX_2026_27/Science-SQP.pdf
- CBSE, Science (086) Marking Scheme, Class X, 2026-27. cbseacademic.nic.in/web_material/SQP/ClassX_2026_27/Science-MS.pdf
- NCERT, Science, Textbook for Class X (Reprint 2026-27), front matter, contents (PDF page 11). ncert.nic.in/textbook/pdf/jesc1ps.pdf
Every number and syllabus fact on this page is from the documents above. The grouping of chapters under units, the summaries and the FAQ wording are ours. Always follow your school and the official CBSE notices.
Practise this class: Class 10 worksheets, chapter by chapter · free practice, marked instantly · timed revision papers