Every key reaction, rule and result from the Class 10 Science NCERT syllabus, organised by chapter, in one place. This page grows as we publish Solutions for each chapter — currently covers Chapters 1-2, with more added as they’re completed.
Class 10 Science Key Reactions & Formulas Handbook
Chapter 1: Chemical Reactions and Equations
- Balancing rule: number of atoms of each element must be equal on both sides of the equation (law of conservation of mass)
- Combination reaction: A + B → AB (e.g. CaO + H₂O → Ca(OH)₂)
- Decomposition reaction: AB → A + B, may need heat (thermal), light (photolytic) or electricity (electrolytic) — e.g. 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃ (thermal)
- Displacement reaction: A + BC → AC + B (a more reactive element displaces a less reactive one, e.g. Fe + CuSO₄ → FeSO₄ + Cu)
- Double displacement reaction: AB + CD → AD + CB, often forms a precipitate (e.g. Na₂SO₄ + BaCl₂ → BaSO₄↓ + 2NaCl)
- Oxidation: gain of oxygen / loss of hydrogen; Reduction: loss of oxygen / gain of hydrogen (both happen together in a redox reaction)
- Corrosion: slow attack of metal surface by air/moisture/chemicals (e.g. rusting of iron); Rancidity: oxidation of fats/oils in food causing bad smell/taste
Chapter 2: Acids, Bases and Salts
- Acid + Metal → Salt + H₂↑ (e.g. Zn + H₂SO₄ → ZnSO₄ + H₂)
- Metal carbonate/bicarbonate + Acid → Salt + CO₂↑ + H₂O
- Acid + Base → Salt + Water (neutralisation); ionic form: H⁺ + OH⁻ → H₂O
- Metallic oxide + Acid → Salt + Water | Non-metallic oxide + Base → Salt + Water
- pH scale: 0–14; <7 acidic, =7 neutral, >7 basic
- Chlor-alkali process (making NaOH): 2NaCl + 2H₂O → (electrolysis) → 2NaOH + Cl₂↑ + H₂↑
- Bleaching powder: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
- Plaster of Paris: CaSO₄·2H₂O (gypsum) heated at ~373K → CaSO₄·½H₂O + 1½H₂O
- Common salt formulas: washing soda Na₂CO₃·10H₂O, baking soda NaHCO₃, blue vitriol CuSO₄·5H₂O
More chapters (Metals and Non-metals, Carbon and its Compounds, and beyond) will be appended here as their Solutions are published.
Chapter 3: Metals and Non-metals
- Reactivity series (high to low): K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au
- Metal + O₂ → basic oxide (amphoteric: Al₂O₃, ZnO) | Non-metal + O₂ → acidic oxide
- Displacement: more reactive metal + salt of less reactive metal → new salt + less reactive metal
- Metal + dilute acid → Salt + H₂↑ (only above H in reactivity series)
- Extraction (reactive metals): concentration → oxide (calcination/roasting) → reduction → electrolytic refining
- Aqua regia: 3:1 conc. HCl : conc. HNO₃ — dissolves gold, platinum
- See full Chapter 3 Solutions
Chapter 4: Carbon and its Compounds
- Saturated (alkanes): CₙH₂ₙ⁺₂ | Unsaturated (alkenes): CₙH₂ₙ | (alkynes): CₙH₂ₙ−₂
- Test for unsaturation: bromine water decolourised = unsaturated
- Oxidation: alcohol → carboxylic acid (alkaline KMnO₄)
- See full Chapter 4 Solutions
