CBSE Class 12 Chemistry Important Topics 2027
Every topic ranked by how often and how recently it was asked in 5 board + 2 official sample papers (2022–2026). Blue = board paper, green = sample paper.
Top 10 most important topics
| # | Topic | Chapter | Asked in | Importance |
|---|---|---|---|---|
| 1 | Carbohydrates: classification, structure of glucose/fructose and reactions | Biomolecules | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★★ |
| 2 | Werner's theory, ligands, coordination number and IUPAC nomenclature | Coordination Compounds | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★☆ |
| 3 | Rate of reaction, rate law, order and molecularity | Chemical Kinetics | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025 | ★★★★☆ |
| 4 | Conductance, molar conductivity and Kohlrausch's law | Electrochemistry | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★☆ |
| 5 | Nernst equation and its applications (cell EMF, equilibrium constant, delta G) | Electrochemistry | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| 6 | Colligative properties: relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure | Solutions | Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| 7 | Classification, nomenclature and preparation of amines | Amines | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| 8 | Proteins: amino acids, peptide bond, structure levels and denaturation | Biomolecules | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| 9 | Physical properties and comparison of acidity of alcohols and phenols | Alcohols, Phenols and Ethers | Board 2023Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| 10 | Nucleophilic substitution: SN1 and SN2 mechanisms | Haloalkanes and Haloarenes | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
Chapter-wise important topics
Solutions · Physical Chemistry
| Colligative properties: relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure asked 9× | Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| Determination of molar mass, van't Hoff factor and abnormal molar mass asked 6× | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★☆☆☆ |
| Raoult's law and ideal / non-ideal solutions (positive and negative deviations) asked 5× | Board 2023Board 2024Board 2025Board 2026 | ★☆☆☆☆ |
| Solubility of gases in liquids and Henry's law asked 4× | Board 2023Sample 2025 | ★☆☆☆☆ |
| Types of solutions and expressing concentration (molarity, molality, mole fraction, ppm) asked 2× | Board 2026Sample 2026 | ★☆☆☆☆ |
Electrochemistry · Physical Chemistry
| Conductance, molar conductivity and Kohlrausch's law asked 10× | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★☆ |
| Nernst equation and its applications (cell EMF, equilibrium constant, delta G) asked 12× | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| Batteries, fuel cells and corrosion asked 5× | Board 2024Sample 2026 | ★☆☆☆☆ |
| Galvanic cells, electrode potential and standard cell EMF asked 4× | Board 2023Board 2025Board 2026Sample 2025 | ★☆☆☆☆ |
| Electrolysis, products of electrolysis and Faraday's laws asked 1× | Sample 2025 | ★☆☆☆☆ |
Chemical Kinetics · Physical Chemistry
| Rate of reaction, rate law, order and molecularity asked 14× | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025 | ★★★★☆ |
| Temperature dependence of rate, Arrhenius equation and activation energy asked 5× | Board 2024Board 2025Board 2026Sample 2026 | ★★☆☆☆ |
| Integrated rate equations for zero and first order reactions asked 4× | Board 2022Board 2023Sample 2025Sample 2026 | ★☆☆☆☆ |
| Half-life of a reaction asked 3× | Board 2026Sample 2025 | ★☆☆☆☆ |
| Collision theory and effect of catalyst asked 1× | Board 2023 | ★☆☆☆☆ |
d- and f-Block Elements · Inorganic Chemistry
| General trends in transition elements (atomic/ionic radii, variable oxidation states) asked 10× | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025 | ★★★☆☆ |
| Preparation and properties of KMnO4 and K2Cr2O7 asked 5× | Board 2023Board 2025Board 2026Sample 2026 | ★★☆☆☆ |
| Colour, magnetic properties, catalytic behaviour and complex formation asked 4× | Board 2022Board 2025Sample 2025Sample 2026 | ★☆☆☆☆ |
| Actinoids and general comparison with lanthanoids asked 2× | Sample 2025Sample 2026 | ★☆☆☆☆ |
| Lanthanoids: lanthanoid contraction and its consequences asked 3× | Board 2023Board 2024Board 2026 | ★☆☆☆☆ |
Coordination Compounds · Inorganic Chemistry
| Werner's theory, ligands, coordination number and IUPAC nomenclature asked 14× | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★☆ |
| Valence bond theory, hybridisation and magnetic behaviour asked 7× | Board 2022Board 2024Board 2025Board 2026Sample 2025 | ★★☆☆☆ |
| Crystal field theory: splitting in octahedral/tetrahedral fields, colour and CFSE asked 6× | Board 2023Board 2024Board 2025Board 2026Sample 2025 | ★★☆☆☆ |
| Stability, bonding and importance/applications of coordination compounds asked 3× | Board 2026Sample 2026 | ★☆☆☆☆ |
| Isomerism (structural and stereo) in coordination compounds asked 1× | Board 2023 | ★☆☆☆☆ |
Haloalkanes and Haloarenes · Organic Chemistry
| Nucleophilic substitution: SN1 and SN2 mechanisms asked 8× | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| Nomenclature, nature of C-X bond and methods of preparation asked 6× | Board 2023Board 2024Board 2025Sample 2026 | ★★☆☆☆ |
| Physical properties of haloalkanes and haloarenes asked 4× | Board 2025Sample 2025 | ★☆☆☆☆ |
| Reactions of haloarenes (nucleophilic and electrophilic substitution) asked 3× | Board 2024Board 2025Board 2026 | ★☆☆☆☆ |
| Optical isomerism / chirality and uses of polyhalogen compounds asked 1× | Board 2026 | ★☆☆☆☆ |
Alcohols, Phenols and Ethers · Organic Chemistry
| Physical properties and comparison of acidity of alcohols and phenols asked 8× | Board 2023Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| Reactions of alcohols (dehydration, oxidation, esterification, with HX) asked 8× | Board 2023Board 2024Board 2026Sample 2025 | ★★☆☆☆ |
| Nomenclature and preparation of alcohols, phenols and ethers asked 2× | Sample 2026 | ★☆☆☆☆ |
| Reactions of phenols (electrophilic substitution, Kolbe's, Reimer-Tiemann) asked 3× | Board 2023Board 2025Board 2026 | ★☆☆☆☆ |
| Ethers: Williamson synthesis and chemical reactions asked 2× | Board 2024Sample 2026 | ★☆☆☆☆ |
Aldehydes, Ketones and Carboxylic Acids · Organic Chemistry
| Named reactions: aldol condensation, Cannizzaro, HVZ, Clemmensen/Wolff-Kishner asked 8× | Board 2022Board 2023Board 2024Board 2026Sample 2025Sample 2026 | ★★☆☆☆ |
| Carboxylic acids: preparation, acidic strength and chemical reactions asked 7× | Board 2023Board 2024Board 2025Sample 2025Sample 2026 | ★★☆☆☆ |
| Distinguishing tests (Tollens', Fehling's, iodoform) and relative reactivity asked 7× | Board 2022Board 2023Board 2025Board 2026Sample 2026 | ★★☆☆☆ |
| Nucleophilic addition reactions and their mechanism asked 6× | Board 2022Board 2024Board 2025Board 2026Sample 2025 | ★★☆☆☆ |
| Nomenclature and preparation of aldehydes and ketones asked 3× | Board 2022Sample 2025Sample 2026 | ★☆☆☆☆ |
Amines · Organic Chemistry
| Classification, nomenclature and preparation of amines asked 11× | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| Basic character of amines and comparison of basicity asked 7× | Board 2022Board 2023Board 2024Board 2025Sample 2025 | ★★☆☆☆ |
| Chemical reactions (acylation, carbylamine, reaction with nitrous acid) asked 8× | Board 2022Board 2023Board 2024Board 2026Sample 2026 | ★★☆☆☆ |
| Distinction of primary, secondary and tertiary amines (Hinsberg test) asked 3× | Board 2024Sample 2025Sample 2026 | ★☆☆☆☆ |
| Diazonium salts: preparation, properties and synthetic importance asked 2× | Board 2024Board 2025 | ★☆☆☆☆ |
Biomolecules · Organic Chemistry
| Carbohydrates: classification, structure of glucose/fructose and reactions asked 16× | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★★ |
| Proteins: amino acids, peptide bond, structure levels and denaturation asked 9× | Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★☆☆ |
| Nucleic acids: structure and functions of DNA and RNA asked 1× | Board 2024 | ★☆☆☆☆ |
Importance = how often a topic was asked × how recent, with extra weight for the latest official sample paper.