Class 10 Science Quick Revision

The 2026-27 Science Paper: Pattern, Syllabus Map and Revision Method

This chapter gives the exact shape of the 2026-27 CBSE Class X Science (086) examination before any content revision begins: marks, sections, unit weights, question types, command words, internal assessment and a revision timetable. It is built from the board's curriculum and sample paper, so every later chapter can be read with marks in mind.

KarmSakha preparation topics covered

• Theory paper design: 80 marks, 3 hours, 39 questions in three sections
• Unit-wise marks and the mapping to Biology, Chemistry and Physics sections
• Core, formative-only and unlisted topics in the 2026-27 curriculum
• Competency mix of 50, 30 and 20 percent and question typologies
• Assertion-reason strategy and case-based question reading
• Command words and the marks-to-points rule
• Internal assessment of 20 marks and the 14 prescribed experiments
• Reported two-phase board scheme and a marks-per-hour revision plan

The 2026-27 Paper at a Glance

The Class X Science (Code 086) examination for the 2026-27 session carries 100 marks in total: an 80-mark theory paper written in 3 hours and 20 marks of internal assessment. Everything you revise in the next eight chapters is ultimately examined through that 80-mark paper, so it pays to know its anatomy before opening any subject chapter. The sample question paper (SQP) for 2026-27 contains 39 questions in three sections, all compulsory, with internal choice in some questions. It also carries a note that the question paper design and assessment pattern have not changed for the 2026-27 session, which means the structure described here is the structure the board has signalled you should prepare for.

The three sections follow the three sciences rather than the five curriculum units. Section A is Biology, Section B is Chemistry and Section C is Physics. Counting question by question in the SQP, Section A holds questions 1 to 16 and carries 30 marks, Section B holds questions 17 to 29 and carries 25 marks, and Section C holds questions 30 to 39 and carries 25 marks. CBSE does not print this as a table; it is a count made from the sample paper, so treat it as the best available picture of the layout rather than a statutory rule. Biology is therefore the single largest block, and, together with Physics, it is one of two sections that combine two curriculum units.

The 39 questions come in five mark-sizes. There are 20 questions of 1 mark, 6 of 2 marks, 7 of 3 marks, 3 case or source-based questions of 4 marks and 3 long questions of 5 marks. Check the arithmetic once, because it is a useful habit for the examination hall: 20 + 12 + 21 + 12 + 15 = 80. The twenty one-mark questions are not all the same kind. Sixteen are ordinary multiple-choice questions and four are assertion-reason questions, with two of the four sitting in Section A and one each in Sections B and C.

Two structural features are easy to miss. First, the long questions are all either/or choices: the SQP places its three 5-mark questions at the end of each section (questions 16, 29 and 39), and in each you answer only one of two alternatives. Second, the three 4-mark questions are built on a passage, data table, graph or situation, and are numbered 15, 28 and 38. Both kinds sit at the end of their sections (the case question is second-last, the 5-mark question last), so a student who runs short of time loses the highest-value questions first. Plan the paper from the back as well as the front.

Unit-wise Weightage and Section Mapping

The curriculum divides the 80 theory marks across five units. Unit I, Chemical Substances: Nature and Behaviour, carries 25 marks. Unit II, World of Living, carries 25 marks. Unit III, Natural Phenomena, carries 12 marks. Unit IV, Effects of Current, carries 13 marks. Unit V, Natural Resources, carries 5 marks. These unit marks are the official figures; they add up as 25 + 25 + 12 + 13 + 5 = 80. They matter more than any chapter-wise guess, because they tell you how many marks are available per unit even when a unit contains several textbook chapters.

The unit weightage and the section layout line up neatly once you see how the units are grouped. Section B (Chemistry, 25 marks) is exactly Unit I. Section C (Physics, 25 marks) is Unit III plus Unit IV, that is 12 + 13. Section A (Biology, 30 marks) is Unit II plus Unit V, that is 25 + 5, because the ecosystem and waste topics of Unit V are biological in treatment and appear in the Biology section. In the sample paper, for instance, food-chain and trophic-level questions sit among the Section A items, alongside digestion, reproduction and control and coordination.

What the curriculum does not publish is a mark count for each textbook chapter inside a unit. Unit I mixes chemical reactions, acids and bases, metals, carbon compounds and (as a reading unit) periodic classification, yet only the 25-mark total is fixed. Do not trust any website that claims a precise chapter-wise mark list for 2026-27 unless it cites the board. The sensible response is to revise by unit, weighting each chapter by its share of the unit, and to use the sample paper only as an illustration of how marks tend to be spread across a unit's sub-topics.

Syllabus Map: Core, Formative-Only and Unlisted Topics

The 2026-27 curriculum contains topics of three different kinds, and mixing them up wastes revision hours. Core topics are listed in the syllabus without any restriction and are examined in the year-end paper. Formative-only topics are in the curriculum for reading and school-level assessment, and the document says they are not part of the year-end examination. Unlisted topics, finally, are ones that older textbooks or guidebooks contain but that the 2026-27 curriculum does not mention at all. A student using last year's guide may spend days on this third category without any benefit.

The curriculum flags three groups as assessed only formatively. The first is Periodic Classification of Elements. The second is Evolution, with its sub-topics: acquired and inherited traits, speciation, evolution and classification, tracing evolutionary relationships, fossils, evolution by stages and human evolution. The third is the cluster of Motor, Electromagnetic Induction and Electric Generator within the magnetic-effects unit. The board supplies a reading-material booklet for these, and a learner may write up a portfolio piece on them for internal assessment. This book still covers them concisely, in chapters 3, 7 and 9, so that you can read them and, where your school asks, attempt school-level questions.

Two topics that appear in older books are absent from the 2026-27 Class X curriculum: Sources of Energy and Sustainable Management of Natural Resources. Unit V now lists only Our Environment, covering the ecosystem, environmental problems, ozone depletion, waste production and solutions, and biodegradable versus non-biodegradable substances. If your coaching notes still contain chapters on coal and petroleum, wind and solar energy, or forest and water management, treat them as optional background rather than examination content for this session.

There is one genuine ambiguity, and it is better to face it than to hide it. The teacher note in the curriculum names Heredity and Evolution as not assessed in the year-end examination. Yet the same curriculum lists Mendel's laws and sex determination under Unit II without a formative flag, and the 2026-27 sample paper tests them: a 4-mark case question on monohybrid and dihybrid pea crosses, and a 1-mark question comparing chromosome numbers in gametes and body cells. This book therefore treats Mendelian heredity as core and Evolution as formative-only. If your school or the board issues a clarification that differs, follow that instruction, since it overrides any book.

Question Types and the Competency Mix

The question paper design fixes how much of the paper tests each level of thinking. About 50 percent of the marks are for demonstrating knowledge and understanding, 30 percent for application of knowledge and concepts, and 20 percent for formulating, analysing, evaluating and creating. The permitted typologies are very-short-answer items including objective types, assertion-reasoning, short-answer, long-answer and source- or case-based integrated assessment questions. About one-third of the paper offers internal choice. In plain terms, roughly half the marks reward a clear recall of a definition, law or diagram, while one mark in five asks you to judge or reason about an unfamiliar situation.

A multiple-choice question in the sample paper is rarely a bare definition. Many are set in a small context: a lab set-up, a food label, a table summarising a process, or a short observation about an animal or a material. The options are built from common mistakes, so every wrong option is an error someone makes. The best method is to cover the options, predict the answer from the stem, and then match your prediction. If you read options first, a well-built distractor plants a false memory. For tables in the stem, check each row independently and reject the whole option when one cell is wrong.

An assertion-reason question gives two statements and four fixed choices. The decision is made in a strict order. First judge the assertion alone as true or false. Then judge the reason alone. Only if both are true do you ask the third question: does the reason actually explain the assertion? Students often tick the option 'R explains A' simply because both statements sound scientific. Test it by trying to put the word 'because' between them. If the sentence feels forced or the reason would be equally true for an unrelated assertion, choose the option that says both are true but R is not the explanation.

Case-based questions of 4 marks carry a passage, data set or diagram. In the sample paper each has part A and part B worth 1 mark each, followed by an either/or sub-part (C or D) worth 2 marks, so you answer three parts in all. The early parts usually test direct reading of the given information; the last part asks you to apply a concept to a changed condition, such as altering a length, a thickness, a current or a cross. The 5-mark questions are either/or and often have multi-part wording such as 'I, II' or 'I to IV', usually with a diagram in one part. They reward structured answers: number your parts, label diagrams, and finish each part before moving to the next. Leave no part blank because each part has its own mark.