Board Exam Session 2026-27

Tamil Nadu Board Class 12 Science Chapter Weightage 2026-27

Complete Board Exam Mark Distribution for TNBSE Class 12 Science Subjects

Physics • Chemistry • Biology/Mathematics • Chapter-wise Marks • 70-80 Theory + 20-30 Internal

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4 Core Subjects 70-80 Theory Marks 20-30 Internal Marks 35% Passing Criteria

Chapter-wise Weightage for Science Board Exams 2026-27

Detailed mark distribution for each subject to help you prioritize your board exam preparation. Use this to plan your study schedule effectively.

Physics - Chapter Weightage (80 Marks)

Unit	Topics Covered	Marks	Weightage
Electrostatics	Electric Charges and Fields - Coulomb's Law, Gauss's Law Electric Potential and Capacitance - Capacitors, Dielectrics	15	18.75%
Current Electricity	Ohm's Law, Kirchhoff's Laws, Wheatstone Bridge Potentiometer and its Applications	14	17.5%
Magnetic Effects	Biot-Savart Law, Ampere's Law, Lorentz Force Magnetic Properties of Materials	12	15%
Electromagnetic Induction	Faraday's Law, Lenz's Law, Self and Mutual Induction AC Circuits, Transformers	12	15%
Optics	Ray Optics - Reflection, Refraction, Lenses Wave Optics - Interference, Diffraction, Polarization	12	15%
Modern Physics	Photoelectric Effect, Atoms, Nuclei Semiconductor Electronics - Diodes, Transistors	15	18.75%
Total		80	100%

Internal Assessment: 20 marks (Periodic Tests - 10, Notebook - 5, Practical - 5)

Chemistry - Chapter Weightage (70 Marks)

Unit	Topics Covered	Marks	Weightage
Physical Chemistry	Solutions, Electrochemistry, Chemical Kinetics Thermodynamics - Laws, Enthalpy, Entropy	22	31.4%
Inorganic Chemistry	p-Block Elements, d-Block and f-Block Elements Coordination Compounds - Nomenclature, Isomerism	18	25.7%
Organic Chemistry	Haloalkanes, Alcohols, Aldehydes, Ketones Carboxylic Acids, Amines, Biomolecules, Polymers	20	28.6%
Environmental Chemistry	Environmental Pollution, Green Chemistry Waste Management - Recycling, Biodegradation	10	14.3%
Total		70	100%

Internal Assessment: 30 marks (Periodic Tests - 10, Notebook - 5, Practical - 10, Project - 5)

Biology - Chapter Weightage (70 Marks)

Unit	Topics Covered	Marks	Weightage
Plant Physiology	Photosynthesis, Respiration in Plants Plant Growth and Development, Mineral Nutrition	18	25.7%
Animal Physiology	Digestion, Breathing, Circulation, Excretion Neural Control, Chemical Coordination	22	31.4%
Genetics & Evolution	Mendelian Genetics, Molecular Basis of Inheritance Evolution, Genetic Disorders	15	21.4%
Ecology & Environment	Organisms and Populations, Ecosystem, Biodiversity Environmental Issues, Sustainable Development	15	21.4%
Total		70	100%

Internal Assessment: 30 marks (Periodic Tests - 10, Notebook - 5, Practical - 10, Project - 5)

Mathematics - Chapter Weightage (80 Marks)

Unit	Topics Covered	Marks	Weightage
Calculus	Continuity and Differentiability Application of Derivatives, Integrals Application of Integrals, Differential Equations	25	31.25%
Vectors and 3D Geometry	Vectors - Algebra, Dot and Cross Product Three Dimensional Geometry - Lines, Planes Linear Programming - Graphical Method	15	18.75%
Probability	Conditional Probability, Bayes' Theorem Random Variables and Probability Distributions	15	18.75%
Relations and Functions	Relations and Functions - Types, Composition Inverse Trigonometric Functions - Properties Matrices and Determinants - Operations	15	18.75%
Statistics	Measures of Central Tendency, Dispersion Correlation and Regression Analysis Index Numbers and Time Series	10	12.5%
Total		80	100%

Internal Assessment: 20 marks (Periodic Tests - 10, Notebook - 5, Subject Enrichment - 5)

Smart Board Exam Preparation Tips Based on Weightage

Focus on High-Weightage Topics

Prioritize units with higher marks like Electrostatics and Modern Physics in Physics (15 marks each), Physical Chemistry in Chemistry (22 marks), and Animal Physiology in Biology (22 marks).

Balance Subjects Effectively

Allocate study time proportionally to the weightage of each subject. Physics and Mathematics need more problem-solving time.

Internal Assessment Matters

Don't ignore the 20-30 internal marks. Submit notebooks on time, participate in periodic tests, and complete practical work diligently for maximum marks.

Practice Competitive Exam Questions

Solve JEE/NEET level questions from high-weightage chapters. This helps in both board exams and competitive exams.

Frequently Asked Questions About Chapter Weightage

How is the chapter weightage useful for board exam preparation?

Chapter weightage helps students prioritize their study time effectively for board exams. By knowing which chapters carry more marks, you can allocate more time to high-weightage topics while still covering all units. This strategic approach ensures better board exam results with efficient preparation.

Does the chapter weightage change every year?

The chapter weightage is generally consistent year to year, but it's advisable to check the official TNBSE website for any updates. Minor changes may occur based on curriculum revisions.

What is the passing criteria for Class 12 Science board exams?

Students must secure a minimum of 35% marks in each subject to pass the board examination. This applies to both theory and internal assessment components combined. Failure in any subject requires supplementary examination.

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