Science Class 10 — Complete Notes NCERT

Chapter 1: Chemical Reactions and Equations

Chemical equation:

Reactants → Products
2H₂ + O₂ → 2H₂O

Types of chemical reactions:

| Type | Example | |---|---| | Combination | A + B → AB | | Decomposition | AB → A + B | | Displacement | A + BC → AC + B | | Double Displacement | AB + CD → AD + CB | | Oxidation | 2Mg + O₂ → 2MgO | | Reduction | CuO + H₂ → Cu + H₂O | | Endothermic | absorbs heat | | Exothermic | releases heat | | Precipitation | AgNO₃ + NaCl → AgCl↓ + NaNO₃ |

Balancing equations — atoms of each element must be equal on both sides.

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Chapter 2: Acids, Bases and Salts

| Property | Acid | Base | |---|---|---| | pH | < 7 | > 7 | | Litmus | Turns red | Turns blue | | Taste | Sour | Bitter, soapy | | Examples | HCl, H₂SO₄, CH₃COOH | NaOH, Ca(OH)₂, NH₄OH |

Neutralization: Acid + Base → Salt + Water

HCl + NaOH → NaCl + H₂O

pH scale: 0 to 14 (7 = neutral)

Important salts:

| Salt | Formula | Use | |---|---|---| | Baking soda | NaHCO₃ | Baking, antacid | | Washing soda | Na₂CO₃·10H₂O | Cleaning | | Bleaching powder | Ca(OCl)Cl | Disinfectant | | Plaster of Paris | CaSO₄·½H₂O | Casts, moulds | | Common salt | NaCl | Food |

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Chapter 3: Metals and Non-metals

Properties of Metals vs Non-metals:

| Property | Metals | Non-metals | |---|---|---| | Lustre | Shiny | Dull | | Hardness | Usually hard | Usually soft (except diamond) | | Malleability | Yes | No (brittle) | | Conductivity | Good | Poor (except graphite) | | Melting point | Usually high | Usually low |

Reactivity series (most to least reactive):

K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Ag > Au

Extraction of metals:

• Most reactive (K, Na, Ca): electrolysis
• Medium reactive (Zn, Fe): roasting/reduction
• Least reactive (Au, Ag): found free in nature

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Chapter 6: Life Processes

Nutrition

• Autotrophic — prepare own food (plants, algae)
• Heterotrophic — depend on others (animals, fungi)

Human digestive system:

Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Anus

• Mouth: salivary amylase (starch → maltose)
• Stomach: pepsin, HCl (protein digestion)
• Small intestine: main absorption site, villi increase area
• Liver: bile production (fat emulsification)

Respiration

Aerobic:   C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP (energy)
Anaerobic: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + 2 ATP (yeast)
                    → 2C₃H₆O₃ + 2 ATP (muscle — lactic acid)

Human respiratory system: Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli

Breathing rate: ~16-20 times/minute Diaphragm contracts → thoracic cavity expands → air enters (inspiration)

Transportation

Blood components:

| Component | Function | |---|---| | RBC | Carry O₂ (haemoglobin) | | WBC | Immunity | | Platelets | Clotting | | Plasma | Transport nutrients, CO₂, hormones |

Human heart — 4 chambers (2 auricles + 2 ventricles), double circulation

• Pulmonary circulation: heart ↔ lungs
• Systemic circulation: heart ↔ body

Blood pressure: systolic/diastolic (normal: 120/80 mmHg)

Excretion

Kidneys (urine) → Ureters → Urinary bladder → Urethra

Nephron = functional unit of kidney
Filtration → Reabsorption → Secretion → Urine

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Chapter 12: Electricity

Ohm's Law: V = IR

Resistors in series:

R_total = R₁ + R₂ + R₃
Same current through all
Different voltage across each

Resistors in parallel:

1/R_total = 1/R₁ + 1/R₂ + 1/R₃
Same voltage across all
Current divides

Electric power:

P = VI = I²R = V²/R  (Watts)
Energy E = P × t      (Joules or kWh)
1 kWh = 3.6 × 10⁶ J  (1 unit of electricity)

Heating effect (Joule's law):

H = I²Rt  (heat produced)
Used in: electric heater, bulb, fuse

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Chapter 13: Magnetic Effects of Electric Current

Magnetic field of straight conductor — circular lines, direction by right-hand thumb rule

Solenoid — coil of wire, acts like a bar magnet when current flows

Electromagnet — iron core + solenoid; magnetism can be switched on/off

Electric motor — converts electrical energy to mechanical energy

• Principle: current-carrying conductor in magnetic field experiences force (F = BIL)
• Split ring commutator maintains rotation

Electromagnetic induction — changing magnetic field induces EMF (Faraday's law)

EMF ε = -N × dΦ/dt  (N = turns, Φ = magnetic flux)

Generator (Dynamo) — converts mechanical energy to electrical

• AC generator: slip rings
• DC generator: commutator

Transformer:

Vs/Vp = Ns/Np = Ip/Is
Step-up: Ns > Np, Vs > Vp
Step-down: Ns < Np, Vs < Vp

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Chapter 9: Heredity and Evolution

Mendel's Laws:

1. Law of Segregation — two alleles separate during gamete formation
2. Law of Independent Assortment — traits inherited independently

Monohybrid cross (Tt × Tt):

Genotype ratio: 1TT : 2Tt : 1tt
Phenotype ratio: 3 Tall : 1 Short

Sex determination in humans:

Female: XX (egg = X only)
Male:   XY (sperm = X or Y)
→ Sex of child determined by father's sperm

Evolution — change in inherited traits over generations

• Natural selection — Darwin's theory
• Acquired traits are NOT inherited (Lamarck was wrong)
• Variations arise due to mutations, sexual reproduction