In short: CBSE Class 10 Science carries 80 marks (theory) + 20 marks (internal assessment) = 100 marks total. The paper is divided into three sections: Physics (~25-27 marks), Chemistry (~25-27 marks), and Biology (~25-27 marks). High-weightage chapters include Chemical Reactions & Equations, Life Processes, Electricity, and Light — Reflection & Refraction. Biology relies heavily on diagrams, Physics on numericals, and Chemistry on equations and reactions. Mastering these four chapters alone covers ~40% of the theory paper.
Science is the subject where most Class 10 students feel the most pressure. The syllabus is vast — 13 chapters spanning Physics, Chemistry, and Biology — and the exam tests everything from numerical problem-solving to diagram labeling to chemical equation balancing.
But here is the good news: the weightage is not equal across chapters. Some chapters consistently carry more marks than others. Understanding this distribution lets you prioritize your preparation and maximize your score.
CBSE Class 10 Science — Unit-Wise Marks Distribution 2027
| Unit No. | Unit Name | Marks |
|---|---|---|
| I | Chemical Substances — Nature and Behaviour | 25 |
| II | World of Living | 23 |
| III | Natural Phenomena | 12 |
| IV | Effects of Current | 13 |
| V | Natural Resources | 07 |
| Total (Theory) | 80 | |
| Internal Assessment | 20 | |
| Grand Total | 100 |
Section-Wise Breakdown: Physics, Chemistry, Biology
Chemistry Section (~25-27 Marks)
| Chapter | Topics | Expected Marks | Importance |
|---|---|---|---|
| Ch 1: Chemical Reactions and Equations | Types of reactions, balancing equations, corrosion, rancidity | 7-8 | Very High |
| Ch 2: Acids, Bases and Salts | pH scale, indicators, neutralization, salt preparation, Plaster of Paris, Baking Soda | 6-8 | Very High |
| Ch 3: Metals and Non-metals | Reactivity series, extraction, ionic bonding, corrosion | 6-8 | High |
| Ch 4: Carbon and its Compounds | Organic chemistry basics, homologous series, functional groups, soap and detergent | 5-7 | High |
| Ch 5: Periodic Classification | Modern periodic table, trends in properties, Mendeleev vs Modern table | 3-4 | Moderate |
Chemistry strategy: Chapter 1 and 2 together can carry 13-16 marks. These are the most predictable chapters. Learn to balance equations correctly and know the properties of acids, bases, and salts. Practice writing chemical equations with state symbols.
Key reactions to memorize:
- Combination, Decomposition, Displacement, Double displacement, Redox
- Reactions of metals with acids, water, and oxygen
- Saponification reaction
- Esterification reaction
Biology Section (~23-25 Marks)
| Chapter | Topics | Expected Marks | Importance |
|---|---|---|---|
| Ch 6: Life Processes | Nutrition, respiration, transportation, excretion in plants and animals | 8-10 | Very High |
| Ch 7: Control and Coordination | Nervous system, hormones, plant hormones, reflex arc | 4-6 | High |
| Ch 8: How Do Organisms Reproduce | Asexual/sexual reproduction, reproductive systems, contraception | 5-7 | High |
| Ch 9: Heredity and Evolution | Mendel's laws, inheritance, evolution, speciation | 4-6 | High |
| Ch 15: Our Environment | Ecosystem, food chains, food webs, ozone depletion, waste management | 2-3 | Low-Moderate |
| Ch 16: Sustainable Management of Natural Resources | (May or may not appear based on syllabus scope) | 1-2 | Low |
Biology strategy: Life Processes is the single most important biology chapter — it alone can carry 8-10 marks. Draw neat, labeled diagrams. In biology, diagrams are worth 2-3 marks each. Practice drawing: human digestive system, human heart, nephron, human brain, male and female reproductive system.
Important diagrams to practice:
| Diagram | Chapter | Expected Marks |
|---|---|---|
| Human digestive system | Life Processes | 2-3 marks |
| Human heart (cross-section) | Life Processes | 2-3 marks |
| Nephron structure | Life Processes | 2 marks |
| Human brain (parts labeled) | Control and Coordination | 2 marks |
| Reflex arc | Control and Coordination | 2 marks |
| Male reproductive system | Reproduction | 2 marks |
| Female reproductive system | Reproduction | 2 marks |
Physics Section (~25-27 Marks)
| Chapter | Topics | Expected Marks | Importance |
|---|---|---|---|
| Ch 10: Light — Reflection and Refraction | Laws of reflection, mirror formula, refraction, lens formula, power of lens | 7-8 | Very High |
| Ch 11: Human Eye and Colourful World | Defects of vision, prism dispersion, scattering of light, atmospheric refraction | 3-4 | Moderate |
| Ch 12: Electricity | Ohm's law, resistance, series/parallel circuits, power, energy | 8-10 | Very High |
| Ch 13: Magnetic Effects of Electric Current | Magnetic field, solenoid, electromagnetic induction, Fleming's rules, electric motor, generator | 4-6 | High |
| Ch 14: Sources of Energy | Conventional/non-conventional energy, solar, wind, nuclear | 2-3 | Low |
Physics strategy: Electricity and Light together carry 15-18 marks (nearly 20% of the paper). These chapters are numerical-heavy. Practice at least 30-40 numerical problems from each chapter. Know all formulas and their applications.
Critical Physics formulas:
| Formula | Chapter | Usage |
|---|---|---|
| V = IR (Ohm's law) | Electricity | Most fundamental |
| R = ρl/A (Resistivity) | Electricity | Material resistance |
| P = VI = I²R = V²/R | Electricity | Power problems |
| H = I²Rt (Joule's heating) | Electricity | Heat generation |
| 1/v - 1/u = 1/f (Mirror formula) | Light | Mirror problems |
| 1/v - 1/u = 1/f (Lens formula) | Light | Lens problems |
| m = v/u (Magnification, mirror) | Light | Image size |
| m = v/u (Magnification, lens) | Light | Image size |
| P = 1/f (Power of lens, f in meters) | Light | Lens power |
| n = sin i / sin r (Snell's law) | Light | Refraction |
CBSE Class 10 Science Paper Pattern 2027
| Question Type | Number of Questions | Marks per Question | Total Marks |
|---|---|---|---|
| MCQ (Multiple Choice) | 20 | 1 | 20 |
| Very Short Answer | 5 | 2 | 10 |
| Short Answer (SA-I) | 6 | 3 | 18 |
| Long Answer (LA) | 4 | 5 | 20 |
| Case-based / Source-based | 3 | 4 (1+1+2) | 12 |
| Total | 38 | 80 |
Questions are spread across Physics, Chemistry, and Biology roughly equally.
Practice CBSE Science on Padhaao
AI tutor with 10 learning modes · Quiz, Flashcards, Exam Practice & more · 3 free chapters daily
High-Priority Chapters — Score Maximum with Focused Study
| Priority | Chapter | Section | Expected Marks | Scoring Difficulty |
|---|---|---|---|---|
| 1 | Electricity | Physics | 8-10 | Moderate (numericals need practice) |
| 2 | Chemical Reactions and Equations | Chemistry | 7-8 | Easy (pattern-based) |
| 3 | Life Processes | Biology | 8-10 | Moderate (diagrams + concepts) |
| 4 | Light — Reflection and Refraction | Physics | 7-8 | Moderate (formula-based numericals) |
| 5 | Acids, Bases and Salts | Chemistry | 6-8 | Easy-Moderate |
| 6 | How Do Organisms Reproduce | Biology | 5-7 | Moderate (diagrams important) |
| 7 | Metals and Non-metals | Chemistry | 6-8 | Moderate (reactivity series) |
| 8 | Control and Coordination | Biology | 4-6 | Moderate |
Top 4 chapters alone: ~30-36 marks (38-45% of theory paper)
Previous Year Analysis — Most Repeated Question Types
| Question Type | Frequency (Last 5 Years) | Typical Marks |
|---|---|---|
| Circuit diagram numericals (Electricity) | Every year | 3-5 marks |
| Balance chemical equations | Every year | 2-3 marks |
| Diagram: Human digestive system / heart | Every year | 2-3 marks |
| Mirror/Lens formula numericals | Every year | 3-5 marks |
| Mendel's experiment explanation | Every year | 3-5 marks |
| Reactivity series applications | Every year | 2-3 marks |
| Carbon compound reactions (esterification, saponification) | 4/5 years | 2-3 marks |
| Fleming's Left/Right Hand Rule | 4/5 years | 2-3 marks |
| Reflex arc diagram and explanation | 4/5 years | 2-3 marks |
| Food chain / food web | 4/5 years | 2-3 marks |
Internal Assessment Breakdown (20 Marks)
| Component | Marks |
|---|---|
| Periodic Tests | 05 |
| Practical / Laboratory work | 05 |
| Portfolio (classwork, homework, assignments) | 05 |
| Subject Enrichment (practical file, lab record, projects) | 05 |
| Total Internal Assessment | 20 |
Practical Component Tips
| Practical | What To Know | Marks Impact |
|---|---|---|
| pH of various solutions | Testing with litmus, pH paper | Appears in both practical and theory |
| Resistors in series/parallel | Circuit setup, readings, calculations | Direct theory marks (Electricity) |
| Focal length of concave mirror/lens | Using candle + screen method | Mirror/Lens formula based questions |
| Observing stomata under microscope | Diagram of stomata, function | Life Processes related |
| Homology and analogy specimens | Identifying similar/different structures | Heredity and Evolution |
Section-Wise Preparation Tips
Physics Tips
- Practice numericals daily: At least 5 problems from Electricity and 5 from Light every day
- Memorize formulas: Make a formula sheet and revise it every morning
- Draw circuit diagrams neatly: Use ruler for straight lines, proper symbols for battery, resistor, ammeter, voltmeter
- Understand sign conventions: For mirrors and lenses, sign convention errors are the #1 reason for wrong answers
Chemistry Tips
- Learn to balance equations first: This is the foundation for the entire chemistry section
- Write state symbols: (s), (l), (g), (aq) — examiners specifically check for these
- Make a reaction chart: For each chapter, list all important reactions on one page
- pH scale: Memorize the pH values of common substances (lemon juice, blood, NaOH, etc.)
Biology Tips
- Diagrams are non-negotiable: Practice drawing and labeling at least 10 key diagrams
- NCERT is everything: In biology, NCERT textbook is the single source of truth — read it line by line
- Difference tables: Make comparison tables (arteries vs veins, mitosis vs meiosis, etc.)
- Flowcharts: Mendel's cross experiments, reflex arc pathway, food chain sequences
Month-Wise Study Strategy
| Month | Focus | Target |
|---|---|---|
| October | Chemistry (Ch 1-5) — all reactions, equations, pH | Complete chemistry section |
| November | Biology (Ch 6-9) — life processes, reproduction, heredity | Complete core biology |
| December | Physics (Ch 10-12) — Light and Electricity + numericals | Complete high-weightage physics |
| January | Physics (Ch 13-14) + Biology (Ch 15-16) + Revision | Complete remaining chapters |
| February | Sample papers, previous year papers, practical preparation | Full paper practice |
| March | Final revision — formulas, diagrams, reactions, weak areas | 1 paper per day minimum |
Frequently Asked Questions
Which section is easiest in CBSE Class 10 Science?
Chemistry is generally considered the most predictable and scoring section. The reactions and concepts follow patterns that repeat every year. Biology requires diagram practice and NCERT reading but is conceptually straightforward. Physics requires the most practice due to numericals.
How to score 70+ in Science?
Focus on (1) Electricity and Light numericals (practice 50+ problems each), (2) all chemical reactions and equations, (3) biology diagrams (draw each at least 5 times), (4) solve 10+ previous year papers. Score well in internal assessment (aim for 18-20/20). This gives you 70+ (50+ in theory + 18-20 internal).
Is NCERT enough for Class 10 Science?
Yes, NCERT is more than enough. CBSE explicitly states that all questions are from NCERT syllabus. Do not waste time on reference books for theory. Use reference books (like Lakhmir Singh, S.Chand) only for extra numerical practice in Physics.
Do we need to memorize all chemical equations?
You need to memorize approximately 25-30 key chemical equations across all chemistry chapters. These include: combination reactions, decomposition, displacement, double displacement, thermal decomposition, electrolysis of water, reactions of metals, and organic reactions. Make a single sheet with all equations and revise daily in the last month.
How important are diagrams in Science?
Very important. In biology alone, diagrams can carry 10-15 marks. A well-drawn, neatly labeled diagram gets full marks even if your written explanation is average. Always use a pencil for diagrams, label all parts, and give a title.
How many numericals come in the exam?
Typically 4-6 numerical questions from Physics (Electricity + Light + occasionally Magnetic Effects) for a total of 12-18 marks. These are the questions that differentiate students who score 60 from those who score 75+. Practice is the only way.
Start Practicing on Padhaao
Chapter-wise weightage tells you what to study. Padhaao helps you actually study it — with practice questions for every chapter, numerical problems with step-by-step solutions, diagram explanations, and CBSE-aligned mock tests. Start with the high-weightage chapters: Electricity, Chemical Reactions, Life Processes, and Light.
₹21/mo (annual plan)
Padhaao covers every CBSE Science chapter
1,005 chapters across all subjects. 2.5 crore+ students. Pro from ₹21/month (annual plan).
Practice CBSE Science chapters with AI
Every chapter from your syllabus. 10 learning modes. 3 free every day.
Start Science