Chat on WhatsAppCBSE gives the Class 10 Science chapter wise weightage for 2026-27 only by unit: 25, 25, 12, 13 and 5 marks of the 80-mark board paper. It does not print marks per chapter. So I counted every question in four official papers: the 2026-27 sample paper, the 2026 main exam, the May 2026 second exam and the 2025 paper. Life Processes had the highest average, 8 marks. Our Environment got exactly 5 in all four.
The unit totals never moved in four papers. The chapters inside a unit moved by as much as 7 marks, so one year's paper is a poor guide to what you can skip.
TL;DR
- By my count, the four-paper chapter averages run from 5 marks (Human Eye, Our Environment) to 8 (Life Processes).
- Light and Human Eye share 12 marks, but Human Eye got 1 mark in the 2025 set I counted and 8 in the May 2026 second-exam set.
- All four papers had the same mix of 39 questions: 16 MCQs, 4 assertion-reason, 6 two-mark, 7 three-mark, 3 case-based and 3 long answers.
- Heredity is still in the board paper. Evolution is for school assessment only.
What is the official CBSE Class 10 Science weightage for 2026-27?
The CBSE Science (086) curriculum for 2026-27 sets an 80-mark theory paper of 3 hours plus 20 marks of internal assessment. The 80 marks are split by unit:
- Unit I, Chemical Substances (Nature and Behaviour): 25 marks, Chapters 1 to 4.
- Unit II, World of Living: 25 marks, Chapters 5 to 8.
- Unit III, Natural Phenomena: 12 marks, Chapters 9 and 10.
- Unit IV, Effects of Current: 13 marks, Chapters 11 and 12.
- Unit V, Natural Resources: 5 marks, Chapter 13.
Chapter numbers follow the NCERT Class X textbook, which CBSE prescribes. About 33% of the paper has internal choice.
These five unit totals are CBSE's only official content weightage, and they are the same as in 2025-26.
What is the CBSE Class 10 Science chapter wise weightage for 2026-27?
Method: I put every question and sub-part of four official papers under one NCERT chapter, using the marks printed against it (for sample paper Q27, the sub-part marks in CBSE's marking scheme), and counted the first option wherever there is an internal choice. The papers are the CBSE sample paper 2026-27, the 2026 main exam (set 31/2/1), the May 2026 second exam (set 31/7/1) and the 2025 exam (set 31/1/1). CBSE prints several sets for each exam (15 Science sets in the 2026 main exam alone). I counted one set from each, so another set of the same exam can split chapters differently. Every paper added up to 80 and matched CBSE's unit marks exactly.
Marks per chapter in each paper, then the four-paper average:
- Ch 1, Chemical Reactions and Equations: sample paper 7, 2026 main 5, May 2026 6, 2025 4; average 5.5.
- Ch 2, Acids, Bases and Salts: sample paper 4, 2026 main 7, May 2026 7, 2025 6; average 6.0.
- Ch 3, Metals and Non-metals: sample paper 7, 2026 main 7, May 2026 6, 2025 10; average 7.5.
- Ch 4, Carbon and its Compounds: sample paper 7, 2026 main 6, May 2026 6, 2025 5; average 6.0.
- Ch 5, Life Processes: sample paper 11, 2026 main 6, May 2026 7, 2025 8; average 8.0.
- Ch 6, Control and Coordination: sample paper 5, 2026 main 7, May 2026 7, 2025 4; average 5.75.
- Ch 7, How do Organisms Reproduce: sample paper 4, 2026 main 6, May 2026 4, 2025 8; average 5.5.
- Ch 8, Heredity: sample paper 5, 2026 main 6, May 2026 7, 2025 5; average 5.75.
- Ch 9, Light (Reflection and Refraction): sample paper 7, 2026 main 6, May 2026 4, 2025 11; average 7.0.
- Ch 10, The Human Eye and the Colourful World: sample paper 5, 2026 main 6, May 2026 8, 2025 1; average 5.0.
- Ch 11, Electricity: sample paper 6, 2026 main 7, May 2026 7, 2025 9; average 7.25.
- Ch 12, Magnetic Effects of Electric Current: sample paper 7, 2026 main 6, May 2026 6, 2025 4; average 5.75.
- Ch 13, Our Environment: sample paper 5, 2026 main 5, May 2026 5, 2025 5; average 5.0.
Source: CBSE question papers (cbse.gov.in) and CBSE Academic sample paper 2026-27 (cbseacademic.nic.in), Gradehunt count.
A few questions sit between two chapters. I put corrosion in Metals and Non-metals, fuse or earth wire questions in Magnetic Effects, and the 2025 lens-power long answer, which also asks about an eye defect, in Light. Moving the corrosion, fuse or chromosome items changes a chapter by 3 marks at most and no unit total. These are past-paper counts, not a CBSE blueprint or a forecast.
Life Processes (8.0), Metals and Non-metals (7.5), Electricity (7.25) and Light (7.0) had the highest averages.
Which chapters change the most from paper to paper?
Unit III swings the most. Light and Human Eye always add up to 12, but the split moves:
- Light ranged from 4 marks (May 2026 second-exam set) to 11 (2025 set).
- Human Eye ranged from 1 mark (2025 set) to 8 (May 2026 second-exam set).
- Life Processes ranged from 6 to 11, the widest spread in Biology.
Our Environment is the opposite: 5 marks every time, always from 1, 2 or 3-mark questions. Electricity got only 1 mark from MCQs and assertion-reason in four papers, while 12 of its 29 marks came from 3-mark short answers on circuits, resistivity and a V-I graph.
Light, Human Eye and Life Processes moved by 5 to 7 marks between papers. Our Environment stayed at 5.
Which chapters gave the 5-mark and case-based questions?
Each paper has three 5-mark long answers and three 4-mark case-based questions, one of each per subject. Across the four papers:
- The 12 long answers came from 10 chapters. Two chapters had two each: Carbon and its Compounds, and How do Organisms Reproduce.
- Three chapters never had a 5-mark question: Acids, Bases and Salts; Heredity; Our Environment.
- The Chemistry case-based question was on Acids, Bases and Salts in all three board-exam sets counted: chlor-alkali, bleaching powder, washing soda, baking soda and Plaster of Paris.
Source: CBSE question papers (cbse.gov.in) and CBSE Academic sample paper 2026-27 (cbseacademic.nic.in), Gradehunt count.
Long answers were spread over 10 chapters, and Acids, Bases and Salts held the Chemistry case study in every board paper counted.
How many questions of each type are in the Science paper?
The mix was identical in all four papers:
- 16 MCQs and 4 assertion-reason questions of 1 mark each (20 marks).
- 6 very short answers of 2 marks (12 marks).
- 7 short answers of 3 marks (21 marks).
- 3 case-based questions of 4 marks (12 marks).
- 3 long answers of 5 marks (15 marks).
The 2025 paper grouped these by type. The 2026 papers and the 2026-27 sample paper group them by subject: Biology, Chemistry and Physics. The 2026 board papers also told students to answer each section in its own part of the answer book.
Expect 39 questions for 80 marks, 20 of them one-mark objective questions.
Is Heredity removed from CBSE Class 10 Science 2026-27?
No. The 2026-27 course content still lists Mendel's laws and sex determination, and the sample paper has 5 marks of Heredity. The confusion comes from the curriculum's Note for Teachers, which names "Heredity and Evolution" among topics that "will not be assessed in the year-end examination". The course content and the sample paper say otherwise.
Three blocks are in the 2026-27 syllabus for school assessment only: Periodic Classification of Elements, Evolution, and the electric motor, electromagnetic induction and generator. None was in the 2025-26 board syllabus, and none of the four papers asked them. Our post on internal assessment marks for Class 10 covers them.
Heredity stays in the 80-mark paper, with 5 to 7 marks in each of the four papers.
Does the second board exam follow the same weightage?
In 2026, yes, by my count. CBSE's circular for the 2026 second exam put it on the syllabus of the first exam, and the May 2026 paper had the same 39-question mix and unit marks. For who can sit it, see how the two board exams work in 2027.
The May 2026 paper kept the 25/25/12/13/5 unit split.
How I would use these numbers before 22 February 2027
CBSE's date sheet puts Science (086) on Monday 22 February 2027, 10:30 AM to 1:30 PM. This is the order I would follow:
- Revise Units I and II first. They carry 50 of the 80 marks.
- Treat Light and Human Eye as one 12-mark block. Each has taken 8 or more marks in at least one of these papers.
- In lens and mirror numericals, fix the sign convention first. One wrong sign carries through every later step.
- Practise circuit and resistivity numericals as 3-mark answers.
- Practise case-based questions on chlor-alkali products, washing soda, baking soda and Plaster of Paris.
- Finish Our Environment early. It gave exactly 5 marks every time.
- Solve full papers in 3 hours from our CBSE Class 10 Science past papers with solutions or CBSE's question papers page.
If you want full papers checked before 22 February, the Gradehunt CBSE Class 10 Science test series has full papers you write by hand and upload. Subject experts check them within 48 hours of upload.
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- 10 November 2026: first published.
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Frequently Asked Questions
Q1.What is the chapter wise weightage of CBSE Class 10 Science 2026-27?
By my count of four official papers, chapters averaged 5 to 8 marks of 80, led by Life Processes (8) and lowest for Human Eye and Our Environment (5). CBSE itself gives only unit marks: 25, 25, 12, 13 and 5. Treat the chapter figures as a guide from the sample paper 2026-27, the 2026 main exam, the May 2026 second exam and 2025, not a fixed blueprint.
Q2.Which chapter has the highest weightage in Class 10 Science?
Life Processes, with an average of 8 marks across the four papers I counted. Metals and Non-metals (7.5), Electricity (7.25) and Light (7.0) come next. Life Processes also swung the most in Biology, from 6 marks in the 2026 main-exam set to 11 in the sample paper.
Q3.Is Heredity removed from CBSE Class 10 Science 2026-27?
No. The 2026-27 course content keeps Mendel's laws and sex determination, and the sample paper has 5 marks from the Heredity chapter, including a 4-mark case study on Mendel's crosses. Evolution, Periodic Classification and the motor and generator topics are for school assessment only. A note in the curriculum mentions Heredity too, but the sample paper shows it is still in the board paper.
Q4.How many MCQs are there in the Class 10 Science paper?
16 MCQs plus 4 assertion-reason questions, so 20 one-mark questions worth 20 of the 80 marks. All four papers I counted had exactly this mix. Life Processes had the most of them: 13 of the 80 one-mark questions across the four papers.
Q5.Is there an official CBSE chapter wise blueprint for Class 10 Science?
No. The 2026-27 curriculum gives marks by unit only. Any chapter wise figure is someone's count of past papers. Ours shows the method and names the four papers, so you can check a chapter yourself against the CBSE question papers.
Q6.When is the CBSE Class 10 Science board exam in 2027?
Monday 22 February 2027, 10:30 AM to 1:30 PM, as per CBSE's date sheet released on 6 November 2026. Class 10 exams run from 16 February to 9 March 2027, so Science falls six days after the first paper.
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