Assam HS (12th) Chemistry Syllabus 2025-26 PDF (Out): AHSEC Unit-wise Topics, Marks Distribution

Assam AHSEC Chemistry Syllabus 2026: Titles & Marks Distribution

The mark distribution for each unit has been mentioned in the table given below for the Chemistry syllabus.

Detailed AHSEC Chemistry Syllabus 2026: Unit-Wise

Students can check out the following Assam HS syllabus 2026 for the Chemistry subject. The Assam AHSEC board has prescribed the syllabus in detail, and candidates need to prepare thoroughly to score well in the board examination. The following syllabus is as per the latest academic year 2026. Check out the sections below.

Unit 1: Solutions

Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid solutions, Raoult's law, colligative properties - relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties, abnormal molecular mass, Van't Hoff factor.

Unit 2: Electrochemistry

• Redox reactions, EMF of a cell, standard electrode potential,

• Nernst equation and its application to chemical cells,

• Relation between Gibbs energy change and EMF of a cell, conductance in electrolytic solutions, specific and molar conductivity, variations of conductivity with concentration.

• Kohlrausch's Law, electrolysis and the law of electrolysis (elementary idea), dry electrolytic cells and Galvanic cells, lead accumulator, fuel cells, corrosion.

Unit 3: Chemical Kinetics

Rate of a reaction (Average and instantaneous), factors affecting rate of reaction: concentration, temperature, catalyst; order and molecularity of a reaction, rate law and specific rate constant, integrated rate equations and half-life (only for zero and first order reactions), concept of collision theory (elementary idea, no mathematical treatment), activation energy, Arrhenius equation.

Unit 4: d and f Block Elements

General introduction, electronic configuration, occurrence and characteristics of transition metals, general trends in properties of the first-row transition metals – metallic character, ionisation enthalpy, oxidation states, ionic radii, colour, catalytic property, magnetic properties, interstitial compounds, alloy formation, preparation and properties of K2Cr2O7 and KMnO4.

• Lanthanoids - Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction and its consequences.

• Actinoids - Electronic configuration, oxidation states and comparison with lanthanoids.

Unit 5: Coordination Compounds

Coordination compounds - Introduction, ligands, coordination number, colour, magnetic properties and shapes, IUPAC nomenclature of mononuclear coordination compounds. Bonding, Werner's theory, VBT, and CFT; structure and stereoisomerism, importance of coordination compounds (in qualitative analysis, extraction of metals and biological systems).

Unit 6: Haloalkanes and Haloarenes

• Haloalkanes: Nomenclature, nature of C–X bond, physical and chemical properties, optical rotation mechanism of substitution reactions.

• Haloarenes: Nature of C–X bond, substitution reactions (Directive influence of halogen in monosubstituted compounds only).

• Uses and environmental effects of dichloromethane, trichloromethane, tetrachloromethane, iodoform, freons, DDT.

Unit 7: Alcohols, Phenols and Ethers

• Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration, uses with special reference to methanol and ethanol.

• Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of phenol, electrophilic substitution reactions, uses of phenols.

• Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses.

Unit 8: Aldehydes, Ketones and Carboxylic Acids

• Aldehydes and Ketones: Nomenclature, nature of the carbonyl group, methods of preparation, physical and chemical properties, mechanism of nucleophilic addition, reactivity of alpha hydrogen in aldehydes, uses.

• Carboxylic Acids: Nomenclature, acidic nature, methods of preparation, physical and chemical properties; uses.

Unit 9: Amines

• Amines: Nomenclature, classification, structure, methods of preparation, physical and chemical properties, uses, identification of primary, secondary and tertiary amines.

• Diazonium salts: Preparation, chemical reactions and importance in synthetic organic chemistry.

Unit 10: Biomolecules

• Carbohydrates - Classification (aldoses and ketoses), monosaccharides (glucose and fructose), D-L configuration oligosaccharides (sucrose, lactose, maltose), polysaccharides (starch, cellulose, glycogen); Importance of carbohydrates.

• Proteins - Elementary idea of - amino acids, peptide bond, polypeptides, proteins, structure of proteins - primary, secondary, tertiary structure and quaternary structures (qualitative idea only), denaturation of proteins, enzymes. Hormones - Elementary idea, excluding structure.

• Vitamins - Classification and functions.

• Nucleic Acids: DNA and RNA.

Assam HS Chemistry Practical Exam Marks Distribution 2026

Detailed AHSEC Assam Chemistry Practical Exam Syllabus 2026