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CBSE Class 10 · Science

Class 10 Science Quick Revision Notes: All Chapters

13 chapters per CBSE 2025-26 syllabus. Equations rendered with MathJax.

  • 13 Chapters
  • 80 Theory Marks
  • 20 Practical
  • 3h Exam Duration

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Prepared by: Muhammad Jaisal · Learnify Academy, Bahrain

Exam Pattern & Strategy

80 marks theory + 20 practical. Removed chapters: 5, 14, 16 (Periodic Classification, Sources of Energy, Natural Resources). Focus on NCERT.

  • 20 MCQs × 1
  • 6 SA × 2
  • 7 SA × 3
  • 3 LA × 5

Exam Tip

Attempt MCQs first, then short answers, then long answers. Always balance equations with state symbols (s, l, g, aq).

Chemical Reactions and Equations

Balancing · Types · Exo/Endothermic · Redox · Corrosion

Key Points

  • Chemical equations must be balanced – atoms conserved. State symbols: (s), (l), (g), (aq).
  • Law of Conservation of Mass: total mass of reactants = total mass of products.
  • Oxidation = gain of O / loss of H. Reduction = loss of O / gain of H. Redox reactions: both occur.
  • Rancidity: oxidation of fats in food – prevented by antioxidants, airtight containers, nitrogen flushing.

Reaction Types

  • Combination: \( \text{CaO}(s) + \text{H}_2\text{O}(l) \rightarrow \text{Ca(OH)}_2(aq) + \text{Heat} \)
  • Endothermic Decomposition: \( 2\text{FeSO}_4(s) \xrightarrow{\Delta} \text{Fe}_2\text{O}_3(s) + \text{SO}_2(g) + \text{SO}_3(g) \)
  • Displacement: \( \text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s) \)
  • Double Displacement (Precipitation): \( \text{KCl}(aq) + \text{AgNO}_3(aq) \rightarrow \text{AgCl}(s)\downarrow + \text{KNO}_3(aq) \)

Law of Conservation of Mass: \( \sum m_{\text{reactants}} = \sum m_{\text{products}} \)

Acids, Bases and Salts

pH scale · Indicators · Important salts · Chlor-alkali

Key Points

  • Arrhenius: Acid → H⁺ in water; Base → OH⁻ in water. pH < 7 acidic, pH = 7 neutral, pH > 7 basic.
  • Indicators: Blue litmus → red in acid; red litmus → blue in base. Phenolphthalein: colourless in acid, pink in base.
  • Chlor-alkali process: \( 2\text{NaCl}(aq) + 2\text{H}_2\text{O}(l) \xrightarrow{\text{electrolysis}} 2\text{NaOH}(aq) + \text{Cl}_2(g) + \text{H}_2(g) \). Products: NaOH, Cl₂, H₂.
  • Key salts: NaHCO₃ (baking soda), Na₂CO₃·10H₂O (washing soda), CaOCl₂ (bleaching powder), CaSO₄·½H₂O (Plaster of Paris).
  • Acid + Base → Salt + Water: \( \text{NaOH}(aq) + \text{HCl}(aq) \rightarrow \text{NaCl}(aq) + \text{H}_2\text{O}(l) \)
  • Baking Soda Heated: \( 2\text{NaHCO}_3(s) \xrightarrow{\Delta} \text{Na}_2\text{CO}_3(s) + \text{H}_2\text{O}(g) + \text{CO}_2(g)\uparrow \)

Metals and Non-metals

Reactivity series · Extraction · Corrosion · Thermite

Key Points

  • Metals: lustrous, malleable, ductile, good conductors, form basic oxides. Non-metals: dull, brittle, poor conductors, form acidic oxides.
  • Reactivity series (most to least): K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au.
  • Extraction: Highly reactive → electrolytic reduction; moderately reactive → carbon reduction; less reactive → native state.
  • Thermite reaction: \( \text{Fe}_2\text{O}_3(s) + 2\text{Al}(s) \rightarrow \text{Al}_2\text{O}_3(s) + 2\text{Fe}(l) + \text{Heat} \) – used for welding.

Carbon and its Compounds

Catenation · Homologous series · Functional groups · Soaps & detergents

Key Points

  • Catenation: carbon’s ability to bond with itself, forming long chains. Tetravalency: forms 4 covalent bonds.
  • Homologous series: compounds with same functional group, differing by –CH₂–. Alkanes: CₙH₂ₙ₊₂; Alkenes: CₙH₂ₙ; Alkynes: CₙH₂ₙ₋₂.
  • Esterification: \( \text{C}_2\text{H}_5\text{OH} + \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O} \). Saponification: fat/oil + NaOH → soap + glycerol.
  • Substitution (UV light): \( \text{CH}_4(g) + \text{Cl}_2(g) \xrightarrow{h\nu} \text{CH}_3\text{Cl}(g) + \text{HCl}(g) \)
  • Addition (Hydrogenation): \( \text{CH}_2{=}\text{CH}_2(g) + \text{H}_2(g) \xrightarrow{\text{Ni}} \text{CH}_3\text{CH}_3(g) \)

Life Processes

Photosynthesis · Respiration · Nutrition · Circulation · Excretion

Key Equations

  • Photosynthesis: \( 6\text{CO}_2 + 6\text{H}_2\text{O} \xrightarrow{\text{Sunlight + Chlorophyll}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \)
  • Aerobic Respiration: \( \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{Energy (ATP)} \)
  • Anaerobic in Yeast: \( \text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_2\text{H}_5\text{OH} + 2\text{CO}_2 + \text{Energy} \)
  • Xylem: transports water and minerals upward. Phloem: transports food (sucrose) bidirectionally.
  • Nephron: ultrafiltration in Bowman’s capsule → selective reabsorption → urine formation.

Control and Coordination

Reflex arc · Nervous system · Hormones · Plant hormones

  • Reflex arc: Stimulus → Receptor → Sensory neuron → Relay neuron (spinal cord) → Motor neuron → Effector → Response (does NOT involve brain).
  • Brain: Cerebrum (thinking, memory), Cerebellum (balance), Medulla oblongata (involuntary actions).
  • Hormones: Insulin (lowers blood glucose), Glucagon (raises blood glucose), Adrenaline (fight or flight), Thyroxine (regulates metabolism).
  • Plant hormones: Auxins (phototropism), Gibberellins (stem elongation), Cytokinins (cell division), Abscisic acid (stomatal closure).

How do Organisms Reproduce?

Asexual · Sexual in plants · Sexual in humans · Contraception

  • Asexual: binary fission (amoeba), budding (yeast), spore formation (rhizopus), regeneration (planaria), vegetative propagation (potato).
  • Sexual reproduction in plants: flower → pollination → fertilization (pollen tube) → zygote → seed → fruit.
  • Male: testes produce sperm; Female: ovaries release ovum. Fertilization in fallopian tube → zygote → embryo implants in uterus.
  • Contraception: barrier (condom), chemical (pills), IUD (copper-T), surgical (vasectomy/tubectomy).

Heredity and Evolution

Mendel’s laws · Punnett squares · Sex determination · Natural selection

  • Mendel’s monohybrid cross F₂ ratio: 3 dominant : 1 recessive. Dihybrid cross F₂ ratio: 9:3:3:1.
  • Sex determination in humans: Female XX, Male XY. Father determines sex of child (X → girl, Y → boy).
  • Homologous structures (same origin, different functions) indicate common ancestry. Analogous structures (different origin, similar function) indicate convergent evolution.
  • Natural selection (Darwin): favourable variations increase survival and reproduction → gradual evolution.

Light – Reflection and Refraction

Mirror & lens formula · Magnification · Snell’s law

  • \( m = -\frac{v}{u} \): Mirror: \( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \)
  • \( m = \frac{v}{u} \): Lens: \( \frac{1}{f} = \frac{1}{v} – \frac{1}{u} \)
  • Refractive index \( n = \frac{c}{v} \): Snell’s Law: \( n_1 \sin\theta_1 = n_2 \sin\theta_2 \)
  • Lens Power: \( P = \frac{1}{f(\text{m})} \) (Diopters)
  • Concave mirror: real, inverted images (object beyond F); virtual, erect, magnified (object between F and P).
  • Convex lens: converges light; concave lens diverges light.
  • Dispersion: white light splits into VIBGYOR by prism – red deviates least, violet most.

Human Eye and the Colourful World

Eye structure · Vision defects · Atmospheric refraction · Tyndall effect

  • Myopia (short-sight): concave lens correction. Hypermetropia (long-sight): convex lens correction.
  • Power of accommodation: ability of eye lens to change focal length to see near/far objects.
  • Blue sky: Rayleigh scattering ∝ 1/λ⁴ – blue light scattered most. Red sunrise/sunset: longer path, blue scattered away.
  • Stars twinkle due to atmospheric refraction; planets do not twinkle (extended sources).

Electricity

Ohm’s law · Resistance · Series & parallel · Power · Joule’s law

  • Ohm’s Law: \( V = IR \)
  • Resistivity (ρ in Ω·m): \( R = \rho \frac{l}{A} \)
  • Electric power: \( P = VI = I^2R = \frac{V^2}{R} \)
  • Joule’s law of heating: \( H = I^2Rt \)
  • Parallel: \( \frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \cdots \): Series: \( R_s = R_1 + R_2 + \cdots \)

Magnetic Effects of Electric Current

Oersted · Fleming’s rules · Motor · Generator · Domestic circuits

  • Fleming’s Left-Hand Rule (motor): Forefinger = Field, Middle finger = Current, Thumb = Motion/Force.
  • Fleming’s Right-Hand Rule (generator): Forefinger = Field, Thumb = Motion, Middle finger = Induced Current.
  • Electric motor: converts electrical → mechanical energy. Generator: converts mechanical → electrical energy.
  • Domestic circuits: Live (220 V), Neutral (0 V), Earth (safety). Appliances connected in parallel.

Force on current-carrying conductor: \( F = BIl \)

Our Environment

Ecosystem · Food chains · 10% energy rule · Biomagnification · Ozone

  • 10% energy rule: only ~10% of energy transfers from one trophic level to the next; 90% lost as heat.
  • Biomagnification: non-biodegradable chemicals (DDT) increase in concentration at higher trophic levels.
  • Ozone layer (stratosphere) absorbs harmful UV radiation. CFCs cause ozone depletion → ozone hole.
  • 3 R’s: Reduce, Reuse, Recycle – sustainable waste management.

Quick Revision Tips & Exam Strategy

Last-minute pointers to maximise your score

  • Formulas Cheat Sheet Mirror: \(1/f=1/v+1/u\), Lens: \(1/f=1/v-1/u\), Ohm’s \(V=IR\), Power \(P=VI\).
  • Attempt Order MCQs first → 2-mark → 3-mark → 5-mark with diagrams.
  • Balance Equations Always include state symbols. Double-check coefficients.
  • Label Diagrams Human eye, nephron, ray diagrams – labels earn full marks.
  • Mirror vs Lens Mirror: \(m=-v/u\); Lens: \(m=v/u\). Formula signs differ.
  • High-Yield Topics Chemical equations, Life processes, Electricity numericals, Reflection, Heredity.