CBSE Class 10 Science NCERT Solutions Class 10 Science Chapter 1 to 16 All (2025–2026 Guide)

Mastering the official curriculum using CBSE Class 10 Science NCERT Solutions Class 10 Science Chapter 1 to 16 All is the most reliable strategy to secure a 95+ score in your 2025–2026 board exam 10. In CBSE Science, NCERT textbooks serve as the fundamental benchmark for question design, marking schemes, and conceptual evaluation. This comprehensive guide provides chapter-by-chapter conceptual breakdowns, high-yield chemical equations, derivation formulas, and model board answers across Physics, Chemistry, and Biology.

Key Concepts: Chapter-by-Chapter Overview (Chapters 1 to 16)

The CBSE Class 10 science syllabus is divided into four major conceptual themes: Chemical Substances, World of Living, Natural Phenomena & Effects of Current, and Natural Resources. Below is an in-depth breakdown of the essential concepts, laws, and chemical reactions across all 16 chapters.

Unit 1: Chemical Substances – Nature and Behaviour (Chapters 1 to 5)

• Chapter 1: Chemical Reactions and Equations: Focuses on balancing chemical equations based on the Law of Conservation of Mass. Key reaction types include combination, decomposition (thermal, electrolytic, photolytic), single displacement, and double displacement (precipitation).
  Redox Reaction Example: CuO + H₂ → Cu + H₂O (where CuO is reduced to Cu, and H₂ is oxidized to H₂O). Corrosion and rancidity represent everyday oxidative degradation.
• Chapter 2: Acids, Bases and Salts: Explores the pH scale (pH = −log[H⁺]), neutralization reactions, and universal indicators. Essential industrial compounds include:
  • Bleaching Powder: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
  • Baking Soda (Sodium Hydrogen Carbonate): NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃
  • Plaster of Paris: CaSO₄·2H₂O + Heat (373 K) → CaSO₄·½H₂O + 1½H₂O
• Chapter 3: Metals and Non-metals: Analyzes physical/chemical properties, the reactivity series, and ionic bond formation via electron transfer (e.g., MgCl₂). Metallurgy processes include calcination (heating carbonate ores in limited air) and roasting (heating sulphide ores in excess air), followed by reduction using carbon or the thermite reaction:
  Fe₂O_3(s) + 2Al_(s) → 2Fe_(l) + Al₂O_3(s) + Heat.
• Chapter 4: Carbon and its Compounds: Details the versatile nature of carbon arising from catenation and tetravalency. Key chemical transformations include:
  • Esterification: CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O (in presence of conc. H₂SO₄)
  • Saponification: CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH
  • Cleansing Action of Soap: Formation of hydrophobic hydrocarbon tails oriented inward and hydrophilic ionic heads (–COO⁻Na⁺) facing outward into water, trapping oily dirt in micelles.
• Chapter 5: Periodic Classification of Elements: Compares early classification attempts (Dobereiner's Triads, Newlands' Law of Octaves, Mendeleev's Periodic Law) with the Modern Periodic Law based on atomic number (Z). Periodic trends across a period (left to right) and down a group:
  • Atomic Radius: Decreases across a period (increased nuclear pull); increases down a group (addition of new shells).
  • Metallic Character: Decreases across a period; increases down a group.

Unit 2: World of Living (Chapters 6 to 9)

• Chapter 6: Life Processes: Covers fundamental physiological mechanisms:
  1. Autotrophic Nutrition: 6CO₂ + 12H₂O + Sunlight + Chlorophyll → C₆H₁₂O₆ + 6O₂ + 6H₂O.
  2. Respiration: Breakdown of glucose in cytoplasm to pyruvate (3-carbon), followed by aerobic breakdown in mitochondria (producing CO₂, H₂O, and 38 ATP) or anaerobic pathways (producing lactic acid in muscle cells or ethanol + CO₂ in yeast).
  3. Transportation: Double circulation in the human heart (pulmonary and systemic loops) preventing the mixing of oxygenated and deoxygenated blood; xylem (unidirectional water transport via transpiration pull) and phloem (bidirectional translocation of sucrose using ATP).
  4. Excretion: Ultrafiltration and selective reabsorption in the nephron (Bowman's capsule, glomerulus, and tubular regions).
• Chapter 7: Control and Coordination: Explains electrical impulses through neurons (dendrite → cell body → axon → synapse via neurotransmitters), reflex arcs bypassing conscious brain processing, and endocrine regulation (insulin, thyroxine, adrenaline, growth hormone). Plant tropisms (phototropism, geotropism, hydrotropism) are mediated by plant hormones such as auxin, gibberellin, cytokinin, and abscisic acid.
• Chapter 8: How do Organisms Reproduce?: Analyzes asexual reproduction (binary/multiple fission, fragmentation, budding, spore formation, vegetative propagation) versus sexual reproduction. Covers the anatomy of angiosperm flowers (pollination, pollen tube growth, double fertilization) and human reproductive systems, along with mechanical, chemical, and surgical contraception methods.
• Chapter 9: Heredity and Evolution: Examines Gregor Mendel's experiments:
  • Monohybrid Cross: Inheritance of one trait yields an F₂ phenotypic ratio of 3:1 and genotypic ratio of 1:2:1.
  • Dihybrid Cross: Independent assortment of two traits yields an F₂ ratio of 9:3:3:1.
  • Sex Determination: Human sex is determined by paternal contribution (XY yields male, XX yields female).

Unit 3: Natural Phenomena & Effects of Current (Chapters 10 to 13)

• Chapter 10: Light – Reflection and Refraction:
  Mirror Formula: 1/f = 1/v + 1/u with magnification m = −v/u = h'/h.
  Lens Formula: 1/f = 1/v − 1/u with magnification m = +v/u = h'/h.
  Power of a Lens: P = 1/f(in metres), expressed in Dioptres (D).
  Snell's Law of Refraction: sin i / sin r = constant (n21).
• Chapter 11: The Human Eye and the Colourful World: Explains eye accommodation and refractive defects:
  • Myopia (Near-sightedness): Image forms in front of the retina; corrected using a concave lens.
  • Hypermetropia (Far-sightedness): Image forms behind the retina; corrected using a convex lens.
  • Presbyopia: Loss of ciliary muscle flexibility; corrected using bifocal lenses.
  • Phenomena: Atmospheric refraction causes the twinkling of stars and advanced sunrise/delayed sunset; Tyndall scattering causes the blue appearance of the clear sky.
• Chapter 12: Electricity:
  Ohm's Law: V = I × R.
  Resistance & Resistivity: R = ρ × (l / A).
  Series Combination: Rs = R1 + R2 + R3 (current I remains constant).
  Parallel Combination: 1/Rp = 1/R1 + 1/R2 + 1/R3 (potential difference V remains constant).
  Joule's Law of Heating: H = I2Rt.
  Electric Power: P = VI = I2R = V2/R (1 kWh = 3.6 × 10⁶ J).
• Chapter 13: Magnetic Effects of Electric Current: Covers magnetic field lines around straight conductors, loops, and solenoids. Key rules include:
  • Right-Hand Thumb Rule: Direction of magnetic field around a current-carrying conductor.
  • Fleming's Left-Hand Rule: Direction of force acting on a current-carrying conductor placed in a magnetic field (applied in electric motors).
  • Electromagnetic Induction & Fleming's Right-Hand Rule: Generation of induced current in a moving conductor within a magnetic field.
  • Domestic Wiring: Live wire (red/brown), neutral wire (black/blue), and earth wire (green/yellow) connected with proper earthing and safety fuses.

Unit 4: Natural Resources and Environment (Chapters 14 to 16)

• Chapter 14: Sources of Energy: Distinguishes conventional energy (fossil fuels, thermal, hydro) from non-conventional alternatives (solar cells, wind energy, biomass/biogas, nuclear fission/fusion, tidal and geothermal energy).
• Chapter 15: Our Environment: Explains food chains, trophic levels, Lindeman's 10% Energy Law (only 10% of energy transfers to the next trophic level), biological magnification (accumulation of non-biodegradable pesticides up the food chain), and the depletion of the stratospheric ozone layer by chlorofluorocarbons (CFCs).
• Chapter 16: Sustainable Management of Natural Resources: Outlines the 5 R's principle (Refuse, Reduce, Reuse, Repurpose, Recycle), traditional water harvesting systems (such as Khadins and Ahars), and community-driven forest conservation movements (e.g., the Chipko Movement and Arabari forest rejuvenation).

Important CBSE Questions with Answers

Question 1 (Chemistry - 3 Marks)

A compound 'X' on heating with excess concentrated sulphuric acid at 443 K gives an unsaturated compound 'Y'. 'X' also reacts with sodium metal to evolve a colourless gas 'Z'. Identify X, Y, and Z, and write the balanced chemical equations involved.

Answer:

1. Identification:
   • Compound X is Ethanol (C₂H₅OH).
   • Compound Y is Ethene (CH₂=CH₂).
   • Gas Z is Hydrogen gas (H₂).
2. Chemical Equations:
   • Dehydration reaction:
     C2H5OH → CH2=CH2 + H2O (in presence of hot conc. H₂SO₄ at 443 K).
   • Reaction with sodium:
     2C2H5OH + 2Na → 2C2H5ONa + H2↑ (Sodium ethoxide and hydrogen gas).

Question 2 (Biology - 3 Marks)

Why is double circulation necessary in human beings? Trace the pathway of blood flow through the heart chambers.

Answer:

• Significance: Double circulation completely separates oxygenated and deoxygenated blood. This ensures high circulatory efficiency and rapid delivery of oxygen to sustain the high energy demands needed to maintain constant body temperature (warm-blooded physiology).
• Pathway:
  1. Deoxygenated blood from body tissues enters the Right Atrium via the vena cava.
  2. The right atrium contracts, pushing blood into the Right Ventricle.
  3. The right ventricle pumps blood to the lungs through the Pulmonary Artery for oxygenation.
  4. Oxygenated blood returns to the Left Atrium via the Pulmonary Veins.
  5. The left atrium contracts, passing blood to the thick-walled Left Ventricle, which pumps oxygenated blood to the entire body via the Aorta.

Question 3 (Physics - 3 Marks)

A concave lens has a focal length of 15 cm. At what distance should an object be placed from the lens so that it forms an image at 10 cm from the lens? Also, calculate the magnification produced.

Answer:

• Given:
  • Focal length of concave lens, f = −15 cm
  • Image distance (concave lens forms virtual image on same side), v = −10 cm
  • Object distance, u = ?
• Applying Lens Formula:
  1/f = 1/v − 1/u ⇒ 1/u = 1/v − 1/f
1/u = (1 / −10) − (1 / −15) = −1/10 + 1/15
1/u = (−3 + 2) / 30 = −1/30
u = −30 cm
  The object must be placed at a distance of 30 cm in front of the lens.
• Magnification:
  m = v / u = (−10 cm) / (−30 cm) = +1/3 = +0.33
  The positive sign indicates a virtual and erect image diminished to one-third of the object size.

Question 4 (Environmental Science - 2 Marks)

If 20,000 J of energy is trapped by producers in an ecosystem, calculate the amount of energy available to tertiary consumers according to Lindeman's 10% law.

Answer:

1. Producers (Trophic Level 1): 20,000 J
2. Primary Consumers / Herbivores (Trophic Level 2): 10% of 20,000 J = 2,000 J
3. Secondary Consumers / Small Carnivores (Trophic Level 3): 10% of 2,000 J = 200 J
4. Tertiary Consumers / Top Carnivores (Trophic Level 4): 10% of 200 J = 20 J

Thus, only 20 J of energy is available to the tertiary consumers.

How to Prepare for This Topic

Maximizing your performance in the Class 10 Science board examination requires a methodical, topic-targeted study regimen:

1. Prioritize High-Weightage Chapters: Allocate structured revision slots to Chemical Reactions, Acids, Bases & Salts, Carbon & its Compounds, Life Processes, Light, and Electricity.
2. Memorize and Practice Chemical Equations: Keep a dedicated formula notebook for state symbols (s, l, g, aq), reaction catalysts, temperature conditions, and color changes (e.g., green FeSO₄ crystals turning reddish-brown Fe₂O₃).
3. Master Standard Ray Diagrams and Circuits: Practice drawing ray diagrams for all 6 object positions of concave mirrors/convex lenses and 2 positions of convex mirrors/concave lenses using a sharp pencil and ruler. Practice circuit schematics with proper ammeter (series) and voltmeter (parallel) placements.
4. Write Structured Answers for Biology: Use labeled flowcharts for cycles (e.g., cardiac cycle, reflex arc, menstrual cycle, urine formation) to capture full presentation marks.
5. Implement Timed Numerical Practice: Dedicate 30 minutes daily to solving sign convention-based numericals in Light and series-parallel resistance networks in Electricity.

Where to Practice More

Solving chapter-wise questions and full-length mock tests under real exam conditions is crucial for mastering time management and question presentation. Access curated chapter tests, CBSE sample papers, and blueprint-aligned practice papers at Theorify QPTool to evaluate your preparation, identify weak areas, and score top marks in your Class 10 board exams.