NCERT Science (Class 6–10) Cheatsheet

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Matter & Materials

CLASS 6–9

What is Matter?

DefinitionAnything that occupies space and has mass

ClassificationElement, Compound, Mixture

StatesSolid, Liquid, Gas (and Plasma)

PropertiesMass, Volume, Density, Shape, Compressibility

Properties of Matter

ParticlesVery small, continuously moving, attract each other

Kinetic energyIncreases with temperature

Intermolecular forceStrongest in solids, weakest in gases

Space between particlesLeast in solids, most in gases

States of Matter — Comparison

Property	Solid	Liquid	Gas
Shape	Fixed, definite shape	No fixed shape (takes container)	No fixed shape (fills container)
Volume	Fixed volume	Fixed volume	No fixed volume
Compressibility	Negligible	Very low	High
Rigidity/Fluidity	Rigid	Fluid	Fluid
Density	High	Lower than solid	Very low
Intermolecular space	Very less	More than solid	Very large
Intermolecular force	Strongest	Weaker than solid	Weakest
Kinetic energy	Least	More than solid	Maximum
Diffusion	Negligible	Moderate	Maximum
Example	Ice, Iron, Wood	Water, Milk, Oil	Oxygen, CO₂, Steam

Phase Changes (State Transitions)

Process	Description	Heat Absorbed/Released	Example
Melting	Solid → Liquid	Absorbed (endothermic)	Ice → Water
Freezing	Liquid → Solid	Released (exothermic)	Water → Ice
Evaporation	Liquid → Gas (surface)	Absorbed (endothermic)	Water → Steam
Boiling	Liquid → Gas (bulk)	Absorbed (endothermic)	Water → Steam at 100°C
Condensation	Gas → Liquid	Released (exothermic)	Steam → Water drops
Sublimation	Solid → Gas (direct)	Absorbed (endothermic)	Camphor, Naphthalene, Dry ice
Deposition	Gas → Solid (direct)	Released (exothermic)	Frost formation

Latent Heat

DefinitionHeat energy absorbed/released during phase change without temperature change

Latent heat of fusionHeat required to melt 1 kg solid at its melting point (Lf)

Latent heat of vaporizationHeat required to vaporize 1 kg liquid at its boiling point (Lv)

Lf of ice3.34 × 10⁵ J/kg (334 kJ/kg)

Lv of water22.6 × 10⁵ J/kg (2260 kJ/kg)

FormulaQ = m × L (Q = heat, m = mass, L = latent heat)

Evaporation vs Boiling

Feature	Evaporation	Boiling
Process	Surface phenomenon	Bulk phenomenon
Temperature	Occurs at any temperature	Occurs at boiling point
Bubbles	No bubbles formed	Bubbles formed throughout
Energy supply	Slow process, heat from surroundings	Requires continuous heat supply
Cooling effect	Produces cooling (e.g., sweating)	No cooling effect
Rate depends on	Surface area, temperature, wind, humidity	External pressure

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Key concept: During phase change (melting, boiling), temperature remains constant even though heat is being supplied. This is because the heat energy is used to break intermolecular bonds (latent heat) rather than increasing kinetic energy of particles.

Changes Around Us — Physical vs Chemical

Feature	Physical Change	Chemical Change
Definition	Change in form/appearance only	New substance(s) formed
Reversibility	Usually reversible	Usually irreversible
Composition	No change in chemical composition	Change in chemical composition
New substance	No new substance formed	One or more new substances formed
Energy change	Little or no energy change	Energy absorbed or released
Example	Melting ice, dissolving sugar, tearing paper	Burning paper, rusting iron, digestion

Pure Substances — Elements, Compounds & Mixtures

Type	Definition	Composition	Example	Separation
Element	Simplest form, made of one type of atom	Single type of atom	Iron (Fe), Gold (Au), Oxygen (O₂)	Cannot be separated further
Compound	Made of two or more elements chemically combined	Fixed ratio by mass	Water (H₂O), NaCl, CO₂	Chemical methods only
Mixture	Two or more substances physically mixed	Variable ratio	Salt water, Air, Sand + Iron	Physical methods

Types of Mixtures

Mixture Type	Homogeneous	Heterogeneous	Examples
Solution (solid-liquid)	✓ Yes	—	Sugar in water, salt in water
Suspension	—	✓ Yes	Muddy water, chalk-water, sand-water
Colloid	✓ Appears homogeneous	✓ Heterogeneous at micro level	Milk, fog, smoke, jelly, ink
Alloy (solid-solid)	✓ Yes	—	Brass, Bronze, Steel
Gas-gas	✓ Yes	—	Air

Tyndall Effect & Colloids

Tyndall effectScattering of light by colloidal particles

True solutionNo Tyndall effect (particles too small)

ColloidShows Tyndall effect

SuspensionShows Tyndall effect

Brownian motionRandom zigzag movement of colloidal particles

ExamplesSunlight through dusty room, headlight in fog, forest canopy light

Separation Techniques

FiltrationSeparate insoluble solid from liquid (mixture of sand + water)

EvaporationSeparate volatile component from non-volatile (salt from water)

DistillationSeparate two miscible liquids with different boiling points

Fractional distillationSeparate miscible liquids with close boiling points (fractionating column)

CentrifugationSeparate denser particles from lighter ones by spinning (cream from milk)

ChromatographySeparate mixture solutes based on different solubilities in same solvent

Magnetic separationSeparate magnetic from non-magnetic (iron from sand)

SublimationSeparate sublimable from non-sublimable (camphor + salt)

DecantationPour off liquid from settled solid (muddy water)

SedimentationHeavier particles settle at bottom naturally

Atoms & Molecules — Dalton's Atomic Theory

Postulate 1All matter is made of very tiny particles called atoms

Postulate 2Atoms are indivisible particles which cannot be created or destroyed in a chemical reaction

Postulate 3Atoms of a given element are identical in mass and chemical properties

Postulate 4Atoms of different elements differ in mass and chemical properties

Postulate 5Atoms combine in simple whole number ratios to form compounds

Postulate 6The relative number and kinds of atoms are constant in a given compound

Atomic Mass & Mole Concept

Atomic mass unit (u)1/12th mass of a C-12 atom; 1u = 1.66 × 10⁻²⁴ g

Molecular massSum of atomic masses of all atoms in a molecule

Formula unit massSum of atomic masses in an ionic compound formula unit

Mole (n)Amount of substance containing 6.022 × 10²³ particles

Avogadro's number (Nₐ)6.022 × 10²³ particles per mole

Molar mass (M)Mass of 1 mole of substance in grams = molecular mass in u

Formulan = given mass / molar mass = N (particles) / Nₐ

Chemical Formulae Rules

ValencyCombining capacity of an element

Crossover methodWrite symbols → exchange valencies → simplify

Polyatomic ionGroup of atoms acting as single unit (SO₄²⁻, NO₃⁻, CO₃²⁻, NH₄⁺)

Example: CaCl₂Ca (valency 2) + Cl (valency 1) → CaCl₂

Example: Al₂(SO₄)₃Al³⁺ + SO₄²⁻ → crossover → Al₂(SO₄)₃

Common valenciesH=1, O=2, N=3, C=4, Na/K=1, Mg/Ca=2, Al=3

Balancing Chemical Equations

Law of conservation of massMass can neither be created nor destroyed (Lavoisier)

Step 1Write the word equation

Step 2Write symbols/formulae of reactants and products

Step 3Count atoms of each element on both sides

Step 4Balance by adjusting coefficients (never change subscripts)

Step 5Verify atom count is equal on both sides

Step 6Make coefficients simplest whole numbers

ExampleFe + H₂O → Fe₃O₄ + H₂ → 3Fe + 4H₂O → Fe₃O₄ + 4H₂

Structure of Atom — Atomic Models

Model	Scientist	Key Points	Limitation
Plum Pudding	J.J. Thomson (1897)	Atom = sphere of +ve charge with electrons embedded like plums	Could not explain Rutherford's scattering experiment
Nuclear	Ernest Rutherford (1911)	All +ve charge & mass in tiny nucleus; electrons orbit around it	Could not explain stability of atom (electron should spiral into nucleus)
Bohr Model	Niels Bohr (1913)	Electrons revolve in fixed energy levels (shells K, L, M, N); no radiation during revolution	Worked only for hydrogen; could not explain spectra of multi-electron atoms

Subatomic Particles

Particle	Symbol	Charge	Mass (u)	Location
Proton	p⁺	+1.6 × 10⁻¹⁹ C	1.0073 u	Nucleus
Neutron	n⁰	0	1.0087 u	Nucleus
Electron	e⁻	-1.6 × 10⁻¹⁹ C	0.00055 u (negligible)	Shells around nucleus

Atomic Number, Mass Number & Isotopes

Atomic number (Z)Number of protons = number of electrons (neutral atom)

Mass number (A)Number of protons + number of neutrons (A = Z + N)

NotationX^A_Z (e.g., ¹⁴₆C → Carbon-14, Z=6, A=14)

IsotopesSame Z (same element), different A (different neutrons)

IsobarsSame A (same mass number), different Z (different elements)

IsotonesSame number of neutrons, different Z and A

Isotope examples¹H, ²H (deuterium), ³H (tritium); ¹²C, ¹⁴C; ³⁵Cl, ³⁷Cl

Electronic Configuration & Valency

Element (Z)	K (2)	L (8)	M (18)	N (32)	Valency
Hydrogen (1)	1	—	—	—	1
Helium (2)	2	—	—	—	0 (duplet complete)
Carbon (6)	2	4	—	—	4
Nitrogen (7)	2	5	—	—	3
Oxygen (8)	2	6	—	—	2
Neon (10)	2	8	—	—	0 (octet complete)
Sodium (11)	2	8	1	—	1
Magnesium (12)	2	8	2	—	2
Aluminium (13)	2	8	3	—	3
Silicon (14)	2	8	4	—	4
Sulphur (16)	2	8	6	—	2
Chlorine (17)	2	8	7	—	1
Argon (18)	2	8	8	—	0 (octet complete)
Potassium (19)	2	8	8	1	1
Calcium (20)	2	8	8	2	2

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Remember: The 2n² rule gives maximum electrons in a shell: K=2, L=8, M=18, N=32. Atoms tend to achieve duplet (2e⁻ in K shell, like He) or octet (8e⁻ in outermost shell, like Ne) configuration for stability. Valency = 8 − valence electrons (for groups 1-2, 13-17).

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Physics

CLASS 9–10

Motion — Fundamental Quantities

Quantity	Type	SI Unit	Definition	Scalar/Vector
Distance	Scalar	metre (m)	Total path length travelled	Scalar
Displacement	Vector	metre (m)	Shortest distance between initial and final position (with direction)	Vector
Speed	Scalar	m/s	Distance travelled per unit time (speed = distance/time)	Scalar
Velocity	Vector	m/s	Displacement per unit time (velocity = displacement/time)	Vector
Acceleration	Vector	m/s²	Rate of change of velocity (a = Δv/Δt)	Vector
Time	Scalar	second (s)	Duration of an event	Scalar

Types of Motion

Uniform motionObject covers equal distances in equal intervals of time (constant velocity, a = 0)

Non-uniform motionObject covers unequal distances in equal intervals (velocity changes)

Uniform circular motionMotion in a circle with constant speed (velocity changes due to direction change)

Acceleration in UCMa = v²/r (directed towards centre, centripetal acceleration)

Example of UCMEarth around Sun, hands of clock, stone tied to string whirled

Speed & Velocity Conversions

km/h to m/sMultiply by 5/18 (e.g., 72 km/h = 20 m/s)

m/s to km/hMultiply by 18/5 (e.g., 10 m/s = 36 km/h)

Average speedTotal distance / Total time

Average velocityTotal displacement / Total time

Uniform speedConstant speed, no acceleration

Non-uniform speedVarying speed, acceleration present

Equations of Motion (Uniform Acceleration)

Equation	Variables	When to Use	Missing Variable
v = u + at	v = final velocity, u = initial velocity, a = acceleration, t = time	When time is known, need final velocity	Distance (s)
s = ut + ½at²	s = displacement	When initial velocity, time, acceleration known	Final velocity (v)
v² = u² + 2as	—	When distance and time not needed	Time (t)
s = ½(u + v)t	—	When initial & final velocity and time known	Acceleration (a)
s = vt - ½at²	—	Alternative form using final velocity	Initial velocity (u)

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Important: These equations apply ONLY to uniformly accelerated motion (constant acceleration). For free fall under gravity: use g = 9.8 m/s² (approx. 10 m/s²). Equations become: v = u + gt, h = ut + ½gt², v² = u² + 2gh.

Distance–Time & Velocity–Time Graphs

Graph Shape	Interpretation	Information Derived
D-T: Straight line (slope)	Uniform speed	Speed = slope of line (Δs/Δt)
D-T: Curved line (parabola)	Acceleration	Slope increasing = speeding up
D-T: Flat horizontal	Body at rest	Speed = 0
V-T: Straight line (slope)	Uniform acceleration	Acceleration = slope (Δv/Δt)
V-T: Flat horizontal	Uniform velocity (a = 0)	No acceleration
V-T: Area under curve	Displacement	Total area = total displacement
D-T graph below time axis	Body returning to start	Can have negative displacement

Force & Newton's Laws of Motion

Law	Statement	Formula	Example
1st Law (Inertia)	A body continues in its state of rest or uniform motion unless acted upon by an unbalanced external force	No formula (defines inertia)	Passenger falls forward when bus stops suddenly
2nd Law	The rate of change of momentum is directly proportional to the applied force and takes place in the direction of force	F = ma; F = dp/dt	Pushing a cart — heavier cart needs more force
3rd Law	Every action has an equal and opposite reaction	F(action) = -F(reaction)	Rocket propulsion, walking, recoil of gun

Momentum & Impulse

Linear momentum (p)p = m × v (mass × velocity); SI unit: kg·m/s

Vector natureMomentum is a vector — has magnitude AND direction

Conservation lawTotal momentum of isolated system remains constant (before = after collision)

Impulse (J)J = F × Δt = Δp (change in momentum); SI unit: N·s

Newton's 2nd lawF = Δp/Δt = mΔv/Δt = ma

Impulse applicationCatching a ball (pull hands back to increase Δt, reduce F)

Conservation of Momentum — Collision

LawTotal momentum before collision = Total momentum after collision

Formulam₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

Elastic collisionBoth momentum AND kinetic energy are conserved

Inelastic collisionOnly momentum is conserved; KE is NOT conserved

Perfectly inelasticObjects stick together after collision: m₁u₁ + m₂u₂ = (m₁+m₂)v

Recoil velocityGun recoil: m₁v₁ + m₂v₂ = 0 → v₁ = -(m₂v₂)/m₁

Gravitation — Universal Law & Related Concepts

Universal Law of GravitationF = G(m₁m₂)/r² — every object attracts every other object

G (Gravitational constant)6.674 × 10⁻¹¹ N·m²/kg² (Henry Cavendish)

g (Acceleration due to gravity)g = GM/R² ≈ 9.8 m/s² on Earth surface

Value of g variesDecreases with altitude, depth; varies with latitude (equator > poles)

g on Moon≈ 1/6 of g on Earth (1.67 m/s²)

MassAmount of matter in body; constant everywhere; scalar; SI unit: kg

WeightForce of gravity on body (W = mg); varies with g; vector; SI unit: Newton

Free fallAll objects fall with same acceleration g (vacuum — no air resistance)

WeightlessnessApparent loss of weight (during free fall, in orbiting spacecraft)

Thrust, Pressure & Buoyancy

ThrustForce acting perpendicular to surface; SI unit: Newton

PressureThrust / Area (P = F/A); SI unit: Pascal (Pa) = N/m²

Atmospheric pressure≈ 1.01 × 10⁵ Pa (1 atm)

Pressure in fluidsIncreases with depth; P = P₀ + ρgh

Buoyant forceUpward force exerted by fluid on immersed object

Archimedes' PrincipleBuoyant force = Weight of fluid displaced by object

Floating conditionObject floats when density < fluid density

Relative densityDensity of substance / Density of water (no unit)

Work, Energy & Power

Work (W)W = F × s × cos θ; SI unit: Joule (J) = N·m

Work doneZero when F ⊥ displacement (θ = 90°) or s = 0

Kinetic energy (KE)KE = ½mv² (energy of a moving body)

Potential energy (PE)PE = mgh (energy due to position/height)

Conservation of energyEnergy can neither be created nor destroyed; only transformed

Power (P)P = W/t; SI unit: Watt (W) = J/s

1 Horsepower1 HP = 746 W

Commercial unit of energy1 kWh = 3.6 × 10⁶ J (1 unit of electricity)

Sound — Production, Propagation & Properties

Property	Definition	Unit / Values	Notes
Sound production	By vibrating objects	—	Needs a vibrating source and a medium
Propagation	Longitudinal wave — compression and rarefaction	Medium needed (solid/liquid/gas)	Cannot travel through vacuum
Speed of sound	Distance travelled per unit time	~344 m/s in air at 20°C	Fastest in solids > liquids > gases
Frequency (f)	Number of oscillations per second	Hertz (Hz)	Audible range: 20 Hz – 20 kHz
Amplitude (A)	Maximum displacement from mean position	Metre (m)	Larger amplitude = louder sound
Wavelength (λ)	Distance between two consecutive compressions/rarefactions	Metre (m)	λ = v/f
Time period (T)	Time for one complete oscillation	Second (s)	T = 1/f
Pitch	How high or low a sound appears	—	Determined by frequency; higher freq = higher pitch
Timbre (quality)	Characteristic that distinguishes two sounds of same pitch & loudness	—	Depends on waveform of sound wave
Loudness	Perceived intensity of sound	Decibel (dB)	Proportional to amplitude²
Infrasonic	Sound below 20 Hz	Hz	Rhinoceros, elephants, earthquakes (< 20 Hz)
Ultrasonic	Sound above 20 kHz	Hz	Bats, dolphins, dolphins, medical ultrasound

Reflection & Echo of Sound

Reflection lawAngle of incidence = Angle of reflection (for sound)

EchoRepeated sound heard due to reflection from a distant surface

Minimum distance for echo17.2 m (to hear distinct echo, time gap ≥ 0.1 s)

Calculation2d = v × t → d = (344 × 0.1)/2 = 17.2 m

ReverberationProlonged sound due to multiple reflections (reduced by sound-absorbing materials)

SONARSound Navigation And Ranging — uses ultrasonic sound to detect objects underwater

Human Ear — Structure & Function

Outer earPinna collects sound → Auditory canal

Eardrum (tympanum)Vibrates when sound hits it; thin membrane

Middle earThree tiny bones (hammer, anvil, stirrup) amplify vibrations

Inner earCochlea converts vibrations to electrical signals

Auditory nerveCarries signals to brain for interpretation

Eustachian tubeEqualizes pressure on both sides of eardrum

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Ultrasound applications: (1) Echocardiography — image of heart, (2) Ultrasonography — image of internal organs, (3) Breaking kidney stones (lithotripsy), (4) Cleaning delicate instruments, (5) Detecting flaws in metals, (6) SONAR for depth measurement and submarine detection.

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Chemistry

CLASS 10

Chemical Reactions & Equations — Types

Type	Definition	General Form	Example
Combination	Two or more substances combine to form a single product	A + B → AB	2Mg + O₂ → 2MgO
Decomposition	A single compound breaks down into two or more simpler substances	AB → A + B	2H₂O → 2H₂ + O₂ (electrolysis)
Displacement	A more reactive element displaces a less reactive element from its compound	A + BC → AC + B	Fe + CuSO₄ → FeSO₄ + Cu
Double displacement	Exchange of ions between two reactants to form new compounds	AB + CD → AD + CB	Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
Oxidation	Gain of oxygen OR loss of hydrogen (oxidizing agent gets reduced)	—	Cu → CuO; H₂S → S
Reduction	Gain of hydrogen OR loss of oxygen (reducing agent gets oxidized)	—	CuO + H₂ → Cu + H₂O
Redox reaction	Both oxidation and reduction occur simultaneously	—	ZnO + C → Zn + CO
Exothermic	Releases heat energy (ΔH < 0)	—	C + O₂ → CO₂ + Heat
Endothermic	Absorbs heat energy (ΔH > 0)	—	CaCO₃ + Heat → CaO + CO₂

Indicators of Chemical Reactions

Change in coloure.g., Iron (grey) + CuSO₄ (blue) → Cu (reddish-brown) + FeSO₄ (green)

Change in temperatureHeat evolved (exothermic) or absorbed (endothermic)

Formation of precipitateInsoluble solid formed (e.g., BaSO₄ in double displacement)

Evolution of gasBubbles produced (e.g., Zn + H₂SO₄ → ZnSO₄ + H₂↑)

Change in stateSolid → liquid, liquid → gas, etc.

Acids, Bases & Salts — Key Concepts

Concept	Acids	Bases
Definition	Substance that produces H⁺ (hydronium H₃O⁺) ions in aqueous solution	Substance that produces OH⁻ ions in aqueous solution
Taste	Sour	Bitter & soapy
Nature	Turn blue litmus → red	Turn red litmus → blue
pH range	0 to 7 (< 7 acidic)	7 to 14 (> 7 basic)
Reaction with metals	H₂ gas evolved (e.g., Zn + H₂SO₄ → ZnSO₄ + H₂)	No H₂ evolved (except with amphoteric metals)
Strong examples	HCl, H₂SO₄, HNO₃	NaOH, KOH, Ca(OH)₂
Weak examples	CH₃COOH (acetic acid), H₂CO₃	NH₄OH (ammonium hydroxide), Mg(OH)₂
Neutralization	Acid + Base → Salt + Water	Base + Acid → Salt + Water

pH Scale — Important Values

pH Value	Substance	Nature
0	1M Hydrochloric acid (HCl)	Strongly acidic
1	Battery acid, Gastric juice	Strongly acidic
2	Lemon juice, Vinegar	Strongly acidic
3	Orange juice, Soft drinks	Acidic
4	Tomato juice, Beer	Acidic
5	Black coffee, Bananas	Weakly acidic
6	Milk, Urine	Weakly acidic
7	Pure water, Saliva	Neutral
8	Sea water, Egg white	Weakly basic
9	Baking soda, Antacid	Weakly basic
10	Milk of magnesia	Basic
11	Ammonia solution	Basic
12	Soapy water	Basic
13	Bleach, Oven cleaner	Strongly basic
14	1M Sodium hydroxide (NaOH)	Strongly basic

Important Chemical Compounds & Their Uses

Compound	Chemical Formula	Common Name	Use
Sodium hydroxide	NaOH	Caustic soda	Soap, paper, drain cleaner
Sodium chloride	NaCl	Common salt	Food, preservative, NaOH & Cl₂ manufacture
Sodium carbonate	Na₂CO₃	Washing soda	Glass, soap, cleaning agent
Sodium bicarbonate	NaHCO₃	Baking soda	Baking, antacid, fire extinguisher
Calcium carbonate	CaCO₃	Limestone/Chalk	Cement, agriculture, antacid
Calcium oxide	CaO	Quicklime	Cement manufacture, soil treatment
Calcium hydroxide	Ca(OH)₂	Slaked lime	Whitewash, sewage treatment
Bleaching powder	Ca(OCl)₂	Bleaching powder	Bleaching cotton/linen, disinfecting water

Preparation of Important Compounds

Bleaching powderCa(OH)₂ + Cl₂ → Ca(OCl)₂ + H₂O (Action of Cl₂ on dry slaked lime)

Baking sodaNaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃ (Solvay process)

Washing sodaNaHCO₃ + heat → Na₂CO₃ + H₂O + CO₂ (Heating baking soda, then recrystallize)

Plaster of ParisCaSO₄·½H₂O (from heating gypsum CaSO₄·2H₂O at 373K)

POP settingCaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O (gypsum — hardens on adding water)

Metals vs Non-metals — Comparison

Property	Metals	Non-metals
Physical state	Solid (except Hg - liquid)	Solid, Liquid, Gas (Bromine = liquid)
Lustre	Metallic shine	Non-lustrous (except I₂, diamond)
Malleability	Can be beaten into thin sheets	Non-malleable (brittle)
Ductility	Can be drawn into wires	Non-ductile
Heat conduction	Good conductors	Poor conductors (except graphite)
Electrical conduction	Good conductors	Poor conductors (except graphite)
Density	Generally high	Generally low
Melting/Boiling point	High	Low
Sonority	Sonorous (ringing sound)	Non-sonorous
Hardness	Generally hard (Na, K exceptions)	Generally soft (diamond exception)

Reactivity Series of Metals

Metal	Reactivity	Reaction with Water	Reaction with Dilute Acid	Extraction
K (Potassium)	Most reactive	Violent	Violent, H₂	Electrolysis
Na (Sodium)	Very reactive	Vigorous	Vigorous, H₂	Electrolysis
Ca (Calcium)	Very reactive	Moderate	Moderate, H₂	Electrolysis
Mg (Magnesium)	Reactive	Slow (hot water)	Brisk, H₂	Electrolysis
Al (Aluminium)	Reactive	Slow	Moderate, H₂	Electrolysis
Zn (Zinc)	Moderately reactive	Very slow	Moderate, H₂	Reduction with C
Fe (Iron)	Moderately reactive	No reaction (cold)	Slow, H₂	Reduction with C/CO
Pb (Lead)	Less reactive	No reaction	Very slow	Reduction with C/CO
Cu (Copper)	Low reactivity	No reaction	No reaction with dilute	Roasting (in nature)
Ag (Silver)	Very low	No reaction	No reaction	In free state
Au (Gold)	Least reactive	No reaction	No reaction	In free state

Corrosion & Its Prevention

CorrosionSlow eating away of metals by action of air, moisture, acids

Rusting of iron4Fe + 3O₂ + 2nH₂O → 2Fe₂O₃·nH₂O (hydrated ferric oxide, brown)

Conditions for rustingPresence of both air (O₂) AND water (moisture)

Prevention: PaintingCoating with paint prevents contact with air/moisture

Prevention: Greasing/OilingForms a protective layer (machinery, tools)

Prevention: GalvanizationCoating iron with zinc (zinc gets oxidized first)

Prevention: AlloyingStainless steel (Fe + Cr + Ni) resists corrosion

Prevention: AnodizingThick oxide layer on Al (decorative + protective)

Important Alloys

Alloy	Composition	Uses
Brass	Cu (60-80%) + Zn	Decorative items, plumbing, musical instruments
Bronze	Cu (88%) + Sn (12%)	Statues, coins, medals, bells
Stainless steel	Fe + C + Cr (10%) + Ni	Utensils, surgical instruments
Solder	Pb + Sn (low melting)	Soldering electrical wires
Amalgam	Any metal + Hg	Dental fillings (Ag-Sn amalgam)

Carbon & Its Compounds — Covalent Bonding

Carbon atomic number6; Electronic config: 2, 4; Valency: 4

Bonding natureCarbon forms covalent bonds (sharing of electrons)

TetravalencyCarbon can share 4 electrons (forms 4 covalent bonds)

CatenationUnique ability to form bonds with other carbon atoms (long chains, rings, branches)

Reason for versatilitySmall size, tetravalency + catenation = millions of compounds

Allotropes of CarbonDiamond (hard, 3D network), Graphite (soft, layers), Fullerene (C₆₀, buckyballs)

Hydrocarbons — Classification

Type	Bond	General Formula	Suffix	Example	Characteristics
Alkane	Single (C–C)	CₙH₂ₙ₊₂	-ane	CH₄ (methane), C₂H₆ (ethane), C₃H₈ (propane)	Saturated hydrocarbons
Alkene	Double (C=C)	CₙH₂ₙ	-ene	C₂H₄ (ethene), C₃H₆ (propene)	Unsaturated hydrocarbons
Alkyne	Triple (C≡C)	CₙH₂ₙ₋₂	-yne	C₂H₂ (ethyne/acetylene), C₃H₄ (propyne)	Unsaturated hydrocarbons
Cyclic	Ring structure	CₙH₂ₙ	cyclo-	Cyclohexane (C₆H₁₂)	Cycloalkanes
Aromatic	Benzene ring	C₆H₆	-benzene	Benzene, Toluene	Delocalized electrons

Isomers & Functional Groups

IsomerismSame molecular formula but different structural arrangement

Isomer exampleC₄H₁₀ → Butane (straight chain) vs Isobutane (branched chain)

Homologous seriesSame functional group, successive members differ by -CH₂

General formulaSame for all members of a series

Gradation in propertiesMelting point, boiling point increase with molecular mass

Important Functional Groups

Functional Group	Formula	Prefix/Suffix	Example
Alcohol	—OH (hydroxyl)	-ol	CH₃OH (methanol), C₂H₅OH (ethanol)
Aldehyde	—CHO (aldehyde)	-al	HCHO (methanal), CH₃CHO (ethanal)
Ketone	—CO— (carbonyl)	-one	CH₃COCH₃ (propanone/acetone)
Carboxylic acid	—COOH (carboxyl)	-oic acid	HCOOH (formic acid), CH₃COOH (acetic acid)
Ester	—COO—	-oate	CH₃COOC₂H₅ (ethyl ethanoate)
Halogen	—X (Cl, Br, I)	chloro/bromo/iodo-	CH₃Cl (chloromethane)

Ethanol (C₂H₅OH) — Properties & Reactions

Physical stateColourless liquid with pleasant smell; boiling point 78°C

SolubilitySoluble in water in all proportions

Reaction with Na2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑ (sodium ethoxide)

DehydrationC₂H₅OH → (conc. H₂SO₄, 443K) → CH₂=CH₂ + H₂O (ethene)

OxidationCH₃CH₂OH → (alk. KMnO₄) → CH₃COOH (acetic acid)

CombustionC₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + Heat (good fuel)

Ethanoic Acid (CH₃COOH) & Soap

Common nameAcetic acid; 5-8% solution = Vinegar

Ester reactionAcid + Alcohol → Ester + Water (esterification, H₂SO₄ catalyst)

SaponificationEster + NaOH → Sodium salt of acid + Alcohol (soap making)

Soap moleculeHas hydrophilic (ionic head) + hydrophobic (carbon chain tail)

Micelle formationIn water, soap molecules cluster: tails inward (oil), heads outward (water)

Soap problemForms scum in hard water (reacts with Ca²⁺/Mg²⁺); detergents don't

Detergent advantageWorks in hard water; is a sodium salt of sulfonic acid

Periodic Classification of Elements

Feature	Mendeleev's Periodic Table (1869)	Modern Periodic Table (1913+)
Basis	Atomic mass	Atomic number (Z = number of protons)
Elements arranged	In order of increasing atomic mass	In order of increasing atomic number
Gaps/Corrections	Left gaps for undiscovered elements	No gaps; all known elements placed correctly
Position of H	Uncertain (group 1 or 7)	Group 1 (alkali metals) — same electronic config
Isotopes	Different positions (same mass)	Same position (same atomic number)
Noble gases	Not included (not discovered)	Group 18 added (all inert gases)
Periods	7 periods	7 periods
Groups	8 groups + 0 group	18 groups (IUPAC numbering)

Modern Periodic Table — Periodic Trends

Trend	Across a Period (L→R)	Down a Group (T→B)
Atomic size (radius)	Decreases (increased nuclear charge pulls electrons closer)	Increases (new shells added)
Valency	Increases from 1 to 4, then decreases from 4 to 0	Remains same (same valence electrons)
Metallic character	Decreases (metals → non-metals → metalloids → non-metals → noble gas)	Increases (less attraction on valence electrons)
Non-metallic character	Increases	Decreases
Ionization energy	Increases (harder to remove electron)	Decreases (outermost electron farther from nucleus)
Electron affinity	Generally increases	Generally decreases
Electronegativity	Increases (more tendency to gain electrons)	Decreases
Reactivity (metals)	Decreases (lose electrons less easily)	Increases (lose electrons more easily)
Reactivity (non-metals)	Increases (gain electrons more easily)	Decreases (gain electrons less easily)

⚠️

Modern Periodic Law: Properties of elements are a periodic function of their atomic numbers. When elements are arranged in increasing order of atomic number, elements with similar properties repeat at regular intervals. The Modern Periodic Table has 7 periods and 18 groups. Lanthanides (57-71) and Actinides (89-103) are placed separately at the bottom.

Groups of Modern Periodic Table & Their Characteristics

Group	Elements	Valence Electrons	Key Characteristics
Group 1 (Alkali metals)	Li, Na, K, Rb, Cs, Fr	1	Highly reactive, soft, low melting point, react vigorously with water, form +1 ions
Group 2 (Alkaline earth)	Be, Mg, Ca, Sr, Ba, Ra	2	Reactive but less than Grp 1, harder, higher melting point, form +2 ions
Group 13 (Boron family)	B, Al, Ga, In, Tl	3	Metallic character increases down group; Boron is metalloid; Al is most useful
Group 14 (Carbon family)	C, Si, Ge, Sn, Pb	4	Carbon — basis of organic chemistry; Si — semiconductors; Sn, Pb — metals
Group 15 (Pnictogens)	N, P, As, Sb, Bi	5	N₂ forms 78% of atmosphere; reactivity decreases down group; form -3 and +5 ions
Group 16 (Chalcogens)	O, S, Se, Te, Po	6	O₂ essential for respiration; form -2 ions; metallic character increases down group
Group 17 (Halogens)	F, Cl, Br, I, At	7	Highly reactive non-metals; toxic; form -1 ions; Cl₂ used as disinfectant
Group 18 (Noble gases)	He, Ne, Ar, Kr, Xe, Rn	8 (2 for He)	Completely filled outermost shell; inert/low reactivity; used in neon signs, balloons

🧬

Biology

CLASS 6–10

Nutrition — Modes & Types

Type	Definition	Organism Example	Process
Autotrophic	Organisms make their own food from simple inorganic substances (CO₂ + H₂O)	Green plants, Algae, Cyanobacteria	Photosynthesis (using chlorophyll + sunlight)
Heterotrophic	Organisms depend on other organisms for food	Animals, Fungi, Most bacteria	Various — holozoic, saprophytic, parasitic
Holozoic	Ingestion of solid organic food, digestion, absorption, assimilation, egestion	Humans, Amoeba, Dog	Ingestion → Digestion → Absorption → Assimilation → Egestion
Saprophytic	Feed on dead & decaying organic matter	Fungi (mushrooms, bread mould), Bacteria	Secrete enzymes on food, absorb digested nutrients
Parasitic	Live on/in a host and derive nutrition from it	Tapeworm, Cuscuta (amarbel), Lice	Absorb nutrients directly from host body
Symbiotic	Two organisms live together and both benefit	Lichen (algae + fungi), Rhizobium + leguminous roots	Mutual exchange of nutrients

Photosynthesis — Process Details

Equation6CO₂ + 6H₂O → (sunlight + chlorophyll) → C₆H₁₂O₆ + 6O₂

SiteChloroplast (leaf mesophyll cells)

PigmentChlorophyll (green pigment) — absorbs mainly red and blue light

Raw materialsCO₂ (stomata) + H₂O (roots → xylem)

ProductsGlucose (C₆H₁₂O₆) + Oxygen (O₂)

Light reactionOccurs in thylakoid membranes; H₂O splits → H⁺ + O₂; ATP & NADPH formed

Dark reaction (Calvin cycle)Occurs in stroma; CO₂ fixed using ATP & NADPH to form glucose

Starch testIodine solution → blue-black colour indicates starch (product of photosynthesis)

Human Digestive System

Organ	Enzyme/Action	Substrate → Product	Notes
Mouth	Salivary amylase (ptyalin)	Starch → Maltose	Mechanical chewing + chemical breakdown
Stomach	Pepsin + HCl	Proteins → Peptides	HCl kills bacteria, activates pepsin; mucus protects lining
Liver	Bile (no enzyme)	Emulsifies fats	Bile breaks large fat globules into smaller droplets
Pancreas	Trypsin, Amylase, Lipase	Proteins → Peptides; Starch → Maltose; Fats → Fatty acids + Glycerol	Released into duodenum
Small intestine	Intestinal juices (maltase, sucrase, lactase, peptidase, lipase)	Maltose → Glucose; Sucrose → Glucose + Fructose; Peptides → Amino acids	Main site of digestion & absorption; villi increase surface area
Large intestine	Absorption of water	Remaining waste → Faeces	Hosts symbiotic bacteria (Vitamin K, B₁₂)
Rectum	Storage	Faeces expelled via anus	Egestion (defecation)

Nutrition in Amoeba (Holozoic)

Step 1Ingestion — Pseudopodia (false feet) engulf food particle forming food vacuole

Step 2Digestion — Complex food breaks down into simpler substances inside food vacuole

Step 3Absorption — Digested nutrients diffuse into cytoplasm

Step 4Assimilation — Nutrients used for energy, growth, repair

Step 5Egestion — Undigested waste expelled by rupturing cell membrane

Living World — Classification (5 Kingdoms)

Kingdom	Cell Type	Nuclear Membrane	Mode of Nutrition	Example
Monera	Prokaryotic (no nucleus)	Absent	Autotrophic/Heterotrophic	Bacteria, Cyanobacteria, Mycoplasma
Protista	Eukaryotic	Present	Autotrophic/Heterotrophic	Amoeba, Paramecium, Euglena, Diatoms
Fungi	Eukaryotic	Present	Heterotrophic (saprophytic)	Mushroom, Yeast, Mould, Penicillium
Plantae	Eukaryotic	Present	Autotrophic	Mosses, Ferns, Conifers, Flowering plants
Animalia	Eukaryotic	Present	Heterotrophic	Insects, Fish, Birds, Reptiles, Mammals

Binomial Nomenclature

Proposed byCarl Linnaeus

SystemTwo-part name: Genus (capitalized) + Species (lowercase)

FormatPrinted in italics; handwritten with underline (e.g., Homo sapiens or Homo sapiens)

RulesUniversally accepted, unique name, Latin or Latinized, no two organisms share same name

ExamplesHomo sapiens (human), Panthera tigris (tiger), Mangifera indica (mango)

HierarchyKingdom → Phylum → Class → Order → Family → Genus → Species

Cell — The Fundamental Unit of Life

Organelle	Function	Present In
Cell membrane (plasma membrane)	Controls entry/exit of substances; selectively permeable; protects cell	Both plant & animal
Cell wall	Provides rigidity & structural support; made of cellulose	Only plant cells
Nucleus	Contains DNA (genetic material); controls cell activities; has nucleolus	Both (absent in RBCs, some cells)
Mitochondria	Powerhouse of cell; produces ATP (energy) through cellular respiration	Both
Endoplasmic reticulum (ER)	Rough ER (ribosomes) — protein synthesis; Smooth ER — lipid synthesis	Both
Golgi apparatus	Packaging, modification & transport of proteins; forms lysosomes	Both
Ribosomes	Site of protein synthesis (translate mRNA to proteins)	Both
Lysosomes	Suicide bags — contain digestive enzymes; break down worn-out cell parts	Both
Vacuole	Storage (water, food, waste); large central vacuole in plants, small in animals	Both
Chloroplast	Site of photosynthesis; contains chlorophyll pigment	Only plant cells
Plastids	Chloroplasts (green), Chromoplasts (coloured), Leucoplasts (colourless storage)	Only plant cells

Cell Division

Feature	Mitosis	Meiosis
Divisions	One	Two successive divisions
Daughter cells	2 (diploid, 2n)	4 (haploid, n)
Chromosome number	Same as parent (2n)	Half of parent (n)
Purpose	Growth, repair, asexual reproduction	Gamete formation (sexual reproduction)
Occurrence	Somatic (body) cells	Germ cells (testes, ovaries)
Genetic variation	No (clones)	Yes (crossing over, independent assortment)
Stages	Prophase, Metaphase, Anaphase, Telophase	Meiosis I (reductional) + Meiosis II (equational)

Plant Cell vs Animal Cell

Feature	Plant Cell	Animal Cell
Cell wall	Present (cellulose)	Absent
Shape	Fixed (rectangular)	Irregular/round
Plastids	Present	Absent
Chloroplast	Present	Absent
Large central vacuole	Present	Small or multiple vacuoles
Centrosome/Centrioles	Absent	Present
Lysosomes	Rare	Present
Nutrition	Autotrophic	Heterotrophic

Tissues — Plant & Animal

Type	Plant Tissues	Animal Tissues
Meristematic / Stem cells	Meristematic — actively dividing, undifferentiated, small cells, dense cytoplasm	Stem cells — found in bone marrow, can differentiate into any cell type
Protective	Epidermis (covers leaves, stem, roots); Cork (suberin-coated, dead)	Squamous epithelium (skin), Stratified squamous (oesophagus)
Connective / Supportive	Parenchyma (storage), Collenchyma (flexible support), Sclerenchyma (hard, lignified, dead)	Connective tissue proper, Bone, Cartilage, Blood, Tendon, Ligament
Muscular	—	Striated (skeletal), Unstriated (smooth), Cardiac (heart)
Conducting / Nervous	Xylem (water & minerals upward), Phloem (food upward & downward)	Nervous tissue — neurons (brain, spinal cord, nerves)
Complex permanent	Xylem: tracheids, vessels, fibres, parenchyma; Phloem: sieve tubes, companion cells	Blood: RBCs, WBCs, platelets, plasma

Life Processes — Respiration

Feature	Aerobic Respiration	Anaerobic Respiration
Oxygen	Required	Not required
Products	CO₂ + H₂O + Energy (38 ATP)	CO₂ + Ethanol + Energy (2 ATP) OR Lactic acid + Energy
Site	Cytoplasm + Mitochondria	Cytoplasm only
Efficiency	High (complete oxidation)	Low (incomplete breakdown)
Equation	C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP	C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + 2 ATP (yeast)
Example	Most living organisms	Yeast (fermentation), muscles during heavy exercise (lactic acid)

Transportation in Plants

XylemTransports water and dissolved minerals from roots to all plant parts (one-directional, upward)

PhloemTransports food (sucrose, amino acids) from leaves to all parts (bidirectional)

TranspirationLoss of water vapour from leaves through stomata; creates pull for upward water movement

Transpiration pullMain driving force for water ascent in xylem (cohesion-tension theory)

Root pressurePushes water upward from roots (active transport in root hair cells)

Capillary actionWater rises in narrow xylem vessels due to adhesion and surface tension

Transportation in Humans

Blood componentsPlasma (55%) + RBCs + WBCs + Platelets

RBCsTransport O₂ (haemoglobin) and CO₂; biconcave, no nucleus; life: 120 days

WBCsFight infection (phagocytosis, antibody production); nucleated; life: few days

PlateletsHelp in blood clotting (thromboplastin → thrombin → fibrin)

Blood vesselsArteries (away from heart, thick walls), Veins (to heart, valves), Capillaries (exchange)

Heart4 chambers (2 atria + 2 ventricles); double circulation; pumps blood

Double circulationPulmonary (heart ↔ lungs) + Systemic (heart ↔ body)

Lymphatic systemLymph (tissue fluid) returns proteins & extracellular fluid to blood

Excretion in Humans

Organ	Waste Removed	Process / Notes
Kidneys	Urea, Uric acid, Excess water, Salts	Nephrons filter blood → urine (1.5 L/day); reabsorption of useful substances
Lungs	CO₂ + Water vapour	Exhaled during breathing
Skin	Water, Salts, Urea (sweat)	Sweat glands; also regulates body temperature
Liver	Bile pigments (bilirubin)	Excreted via bile into intestine → faeces
Large intestine	Undigested solid waste	Egestion (defecation) via rectum and anus

Control & Coordination — Nervous System

Component	Parts	Function
Central Nervous System (CNS)	Brain (cerebrum, cerebellum, medulla) + Spinal cord	Controls all body activities; processes information
Peripheral Nervous System (PNS)	Cranial nerves (12 pairs) + Spinal nerves (31 pairs)	Connects CNS to body organs and limbs
Autonomic Nervous System	Sympathetic (fight or flight) + Parasympathetic (rest & digest)	Controls involuntary functions (heartbeat, digestion)

Parts of Human Brain

CerebrumLargest part; thinking, memory, reasoning, consciousness, voluntary actions

CerebellumCoordinates body movements, posture, balance (behind cerebrum)

Medulla oblongataControls involuntary actions: breathing, heartbeat, blood pressure, coughing, sneezing

HypothalamusMaintains body temperature, hunger, thirst; link between nervous & endocrine systems

PonsRegulates breathing rate; connects cerebrum with cerebellum and medulla

Neuron — Structure & Types

DendriteReceives signals from other neurons (input)

Cell body (cyton)Contains nucleus, cytoplasm; processes signals

AxonLong fibre that transmits signals away from cell body (output)

SynapseGap between two neurons; chemical neurotransmitters carry signals across

Sensory neuronCarries impulses FROM sense organs TO CNS (afferent)

Motor neuronCarries impulses FROM CNS TO effectors/muscles (efferent)

Reflex actionSudden, involuntary response; mediated by spinal cord (reflex arc)

Endocrine Glands — Hormones & Functions

Gland	Hormone(s)	Function	Disorder
Pituitary	Growth hormone (GH), TSH, FSH, LH, ACTH, ADH	Master gland; controls other glands; growth & development	Dwarfism (less GH), Gigantism (excess GH)
Thyroid	Thyroxine (T₄), Triiodothyronine (T₃)	Regulates metabolism, body temperature, growth	Goitre (iodine deficiency), Hypothyroidism, Hyperthyroidism
Adrenal (medulla)	Adrenaline (epinephrine)	Fight-or-flight response; increases heart rate, BP, blood sugar	Addison's disease
Adrenal (cortex)	Cortisol, Aldosterone	Stress response, immune regulation, salt-water balance	Addison's disease, Cushing's syndrome
Pancreas (Islets)	Insulin (β-cells), Glucagon (α-cells)	Insulin lowers blood glucose; Glucagon raises blood glucose	Diabetes mellitus (insufficient insulin)
Testes	Testosterone	Male sex hormone; sperm production, secondary sexual characters	—
Ovaries	Estrogen, Progesterone	Female sex hormones; menstruation, pregnancy, secondary sexual characters	PCOS, infertility
Pineal	Melatonin	Regulates sleep-wake cycle (circadian rhythm)	Sleep disorders
Parathyroid	Parathyroid hormone (PTH)	Regulates calcium and phosphorus levels in blood	Tetany (low PTH)

How Do Organisms Reproduce — Asexual Reproduction

Method	Description	Organism Example	Key Feature
Binary fission	Parent cell divides into two equal daughter cells	Amoeba, Paramecium, Bacteria	Simplest; cell splits along any plane (Amoeba) or transverse (Paramecium)
Multiple fission	Parent cell divides into many daughter cells simultaneously	Plasmodium (malaria parasite)	Cyst formation protects during unfavourable conditions
Budding	Small bud develops on parent body, detaches to form new organism	Yeast, Hydra	Bud may remain attached temporarily (colonies in Hydra)
Fragmentation	Body breaks into fragments, each grows into new organism	Spirogyra (algae), Planaria (flatworm)	Each fragment regenerates missing parts
Spore formation	Spores produced in sporangia; dispersed, germinate into new organism	Rhizopus (bread mould), Ferns, Mushrooms	Spores are asexual reproductive units, covered by thick wall
Vegetative propagation	New plant grows from vegetative parts (root, stem, leaf)	Potato (tuber), Rose (cutting), Bryophyllum (leaf buds)	Genetically identical to parent; used in agriculture
Tissue culture	Growing new plants from tissue/explant on nutrient medium	Orchids, Banana, Sugarcane	Produces disease-free, large numbers of plants quickly

Sexual Reproduction in Flowering Plants

Flower partsSepals (protection), Petals (attract pollinators), Stamens (male — anther + filament), Pistil/Carpel (female — stigma + style + ovary)

PollinationTransfer of pollen from anther to stigma

Self-pollinationPollen from same flower or same plant (e.g., pea, wheat)

Cross-pollinationPollen from different plant of same species (e.g., rose, sunflower)

Agents of pollinationWind, Water, Insects (bees, butterflies), Birds, Bats

FertilizationPollen tube grows → male gamete fuses with female gamete in ovule → zygote formed

Post-fertilizationZygote → Embryo; Ovule → Seed; Ovary → Fruit; Ovary wall → Pericarp (fruit wall)

Seed dispersalWind (light seeds, wings), Water (coconut), Animals (hooks, fleshy fruits), Explosion (bursting pods)

Human Reproductive System

Feature	Male	Female
Gonads	Testes (outside body, scrotum)	Ovaries (inside abdominal cavity)
Gametes	Sperm (motile, microscopic, head + tail)	Ovum/Egg (larger, non-motile, cytoplasm-rich)
Production	Millions daily after puberty	One egg per month (ovulation, ~28-day cycle)
Ducts	Vas deferens → Urethra	Fallopian tubes (oviducts) → Uterus → Vagina
Glands	Prostate gland, Seminal vesicles	—
Fertilization site	— (sperm deposited in vagina)	Fallopian tube (ampulla region)
Implantation	—	Embryo implants in thickened uterine wall (endometrium)
Placenta	-	Provides nutrition, O2, removes waste; acts as barrier

Heredity & Evolution — Mendel's Laws

Law	Statement	Monohybrid Cross Example
Law of Dominance	When organisms with contrasting characters are crossed, the F1 generation shows only one parent character (dominant); the other (recessive) is hidden	TT (tall) × tt (short) → All Tt (tall) in F1
Law of Segregation	Alleles (gene pairs) separate during gamete formation so each gamete receives only one allele	Tt → gametes T and t (separate)
Law of Independent Assortment	Genes for different traits are inherited independently (applies to dihybrid cross)	Round Yellow (RRYY) × Wrinkled Green (rryy) → F2: 9:3:3:1 ratio

Genetic Terminology

GeneUnit of heredity; segment of DNA that codes for a protein

AlleleAlternative forms of a gene (e.g., T = tall, t = short)

GenotypeGenetic makeup of an organism (e.g., TT, Tt, tt)

PhenotypeObservable/physical expression of genotype (e.g., tall, short)

HomozygousBoth alleles same: TT (homozygous dominant) or tt (homozygous recessive)

HeterozygousTwo different alleles: Tt (one dominant, one recessive)

Dominant alleleExpressed in both homozygous and heterozygous conditions (T)

Recessive alleleExpressed only in homozygous condition (tt)

Sex determinationXX = Female; XY = Male (in humans, father determines sex of child)

Evolution — Key Theories

Lamarck (Use & Disuse)Inheritance of acquired characteristics; organs develop with use, degenerate with disuse

Lamarck exampleGiraffe neck → long from stretching to reach leaves (incorrect theory)

Darwin (Natural Selection)Survival of the fittest; organisms with favourable variations survive and reproduce

Darwin exampleFinches on Galapagos — different beak shapes for different food sources

SpeciationFormation of new species due to genetic variation + natural selection + geographical isolation

Homologous organsSame basic structure, different functions (e.g., forelimbs of human, bat, whale — common ancestor)

Analogous organsDifferent structure, similar functions (e.g., wings of insect, bat, bird — different origins)

FossilsPreserved remains/traces; help study evolution (older layers = simpler organisms)

Natural Resources — Biogeochemical Cycles

Cycle	Key Reservoirs	Key Processes	Human Impact
Water cycle	Oceans, Atmosphere, Groundwater	Evaporation, Condensation, Precipitation, Percolation, Transpiration	Deforestation reduces transpiration; pollution contaminates water bodies
Nitrogen cycle	Atmosphere (78% N₂), Soil, Living organisms	Nitrogen fixation (bacteria), Nitrification, Assimilation, Ammonification, Denitrification	Excessive fertilizers → eutrophication; industrial N₂O emissions
Carbon cycle	Atmosphere (CO₂), Oceans, Fossil fuels, Biomass	Photosynthesis, Respiration, Combustion, Decomposition, Formation of fossil fuels	Burning fossil fuels → increased CO₂ → global warming → climate change
Oxygen cycle	Atmosphere (21% O₂), Biosphere	Photosynthesis (produces), Respiration (consumes), Combustion	Deforestation reduces O₂ production

Fossil Fuels

CoalFormed from compressed plant material over millions of years; carbon-rich; used in power plants

PetroleumFormed from dead marine organisms; crude oil; refined into petrol, diesel, kerosene, LPG, bitumen

Natural gasFound above petroleum deposits; mainly methane (CH₄); CNG (Compressed Natural Gas) cleaner fuel

Non-renewableTake millions of years to form; limited reserves; being depleted rapidly

Environmental concernBurning fossil fuels releases CO₂, SO₂, NO₂ → air pollution, acid rain, greenhouse effect

Our Environment — Ecosystem

EcosystemCommunity of living organisms interacting with each other and with their physical environment

Biotic componentsProducers (autotrophs), Consumers (herbivores, carnivores, omnivores), Decomposers

Abiotic componentsSunlight, Temperature, Water, Air, Soil, Minerals

Food chainLinear sequence: Producer → Primary consumer → Secondary consumer → Tertiary consumer

Food webInterconnected network of food chains; more complex, more stable

Energy flowUnidirectional; only 10% energy transferred to next trophic level (10% law)

Biological magnificationConcentration of harmful chemicals increases at each trophic level (DDT example)

Environmental Issues

Issue	Cause	Effects	Solutions
Ozone depletion	CFCs (chlorofluorocarbons) from refrigerants, aerosols	UV rays reach Earth → skin cancer, cataracts, crop damage	Montreal Protocol (1987) — phase out CFCs; use ozone-friendly alternatives
Global warming	Greenhouse gases (CO₂, CH₄, N₂O, CFCs)	Rising temperatures, melting glaciers, rising sea levels, extreme weather	Reduce fossil fuel use, afforestation, renewable energy, carbon capture
Deforestation	Cutting forests for agriculture, urbanization, timber	Soil erosion, loss of biodiversity, climate change, disrupted water cycle	Afforestation, sustainable forestry, wildlife sanctuaries
Water pollution	Industrial effluents, sewage, fertilizers, pesticides	Eutrophication, loss of aquatic life, spread of diseases	Sewage treatment, reduce chemical fertilizers, strict regulations
Air pollution	Vehicle exhaust, industries, burning crop residue	Respiratory diseases, acid rain, smog, visibility reduction	CNG vehicles, pollution controls, public transport, tree belts
Waste management	Excessive plastic, e-waste, solid waste	Land pollution, groundwater contamination, disease spread	3R: Reduce, Reuse, Recycle; composting; proper disposal

💡

Ozone layer: Found in the stratosphere (15-35 km above Earth). Ozone (O₃) absorbs harmful UV-B radiation from the Sun. Ozone depletion is most severe over Antarctica (ozone hole). The Montreal Protocol (1987) has successfully phased out most CFCs, and the ozone layer is gradually recovering.

Nephron — Structural & Functional Unit of Kidney

Bowman's capsuleCup-shaped structure; receives filtrate from blood via glomerulus (network of capillaries)

Glomerular filtrationHigh blood pressure in glomerulus forces water, glucose, urea, salts into Bowman's capsule (ultrafiltration)

Proximal convoluted tubuleSelective reabsorption of glucose, amino acids, Na⁺, water back into blood

Loop of HenleReabsorption of water and NaCl; concentrates urine (longer loop = more concentrated urine)

Distal convoluted tubuleFurther reabsorption of Na⁺, water; secretion of K⁺, H⁺ into filtrate

Collecting ductFinal water reabsorption (controlled by ADH hormone from pituitary)

Urine formationFiltration → Reabsorption → Secretion → Urine (contains water, urea, uric acid, excess salts)

DialysisArtificial kidney machine; filters blood of urea when kidneys fail (uses dialysis membrane)

Respiration in Organisms — Pathway of Air

Nostrils → Nasal cavityAir is filtered, moistened, and warmed (hairs, mucus, blood vessels)

Pharynx → LarynxPassage; epiglottis prevents food from entering trachea (windpipe)

Trachea (windpipe)C-shaped cartilage rings keep it open; lined with ciliated mucous membrane

Bronchi → BronchiolesTrachea divides into 2 bronchi (enter lungs); further divide into bronchioles

Alveoli (air sacs)Tiny balloon-like sacs at end of bronchioles; surrounded by blood capillaries; site of gas exchange

Gas exchangeO₂ diffuses from alveolar air → blood; CO₂ diffuses from blood → alveolar air (concentration gradient)

InhalationDiaphragm contracts (moves down), ribs move up & out → chest cavity expands → air rushes in

ExhalationDiaphragm relaxes (moves up), ribs move down & in → chest cavity contracts → air pushed out

Breathing rateAverage: 12-20 breaths/minute for adult at rest; increases during exercise

💡

Light

CLASS 8, 10

Reflection of Light

Law 1Angle of incidence (i) = Angle of reflection (r)

Law 2Incident ray, reflected ray, and normal all lie in the same plane

Real imageFormed when reflected rays actually meet; can be projected on screen; always inverted

Virtual imageApparent meeting point of reflected rays (extended backwards); cannot be projected; always erect

Plane mirror imageVirtual, erect, same size as object, laterally inverted, same distance behind mirror as object in front

Lateral inversionLeft-right swap (ambulance written reverse so it reads correctly in rear-view mirror)

Spherical Mirrors — Concave & Convex

Feature	Concave Mirror (Converging)	Convex Mirror (Diverging)
Shape	Reflecting surface curved inward (like inside of spoon)	Reflecting surface curved outward (like back of spoon)
Focal point (F)	Real focal point (rays converge in front)	Virtual focal point (rays appear to diverge from behind)
Image — Object at ∞	Highly diminished, real, inverted, at F	Highly diminished, virtual, erect, at F (behind mirror)
Image — Beyond C	Diminished, real, inverted, between F and C	—
Image — At C	Same size, real, inverted, at C	—
Image — Between C and F	Magnified, real, inverted, beyond C	—
Image — At F	Image at infinity (highly magnified)	—
Image — Between F and P	Magnified, virtual, erect, behind mirror	—
Uses	Dentist mirror, shaving mirror, telescope, solar furnace, headlights	Rear-view mirror in vehicles, security mirrors, shop mirrors

Mirror Formula, Magnification & Ray Diagrams

Mirror formula1/v + 1/u = 1/f (u = object distance, v = image distance, f = focal length)

Sign conventionAll distances measured from pole (P); direction of incident light = positive

Magnification (m)m = -v/u = hᵢ/hₒ (height of image / height of object)

m > 1Image is magnified (larger than object)

m < 1Image is diminished (smaller than object)

m = 1Image is same size as object

m positiveImage is virtual and erect

m negativeImage is real and inverted

Radius of curvatureR = 2f (radius of curvature = twice focal length)

Refraction of Light

DefinitionBending of light when it passes from one medium to another (change in speed)

Law 1Incident ray, refracted ray, and normal all lie in the same plane

Law 2 (Snell's Law)n₁ sin i = n₂ sin r (ratio of sines = ratio of refractive indices)

Refractive index (n)n = sin i / sin r = speed of light in vacuum / speed in medium = c/v

Towards normalWhen entering denser medium (slow down, bend towards normal)

Away from normalWhen entering rarer medium (speed up, bend away from normal)

Total internal reflectionLight travels from denser to rarer; angle of incidence > critical angle; all light reflected back

Lenses — Convex & Concave

Feature	Convex Lens (Converging)	Concave Lens (Diverging)
Shape	Thicker at centre, thinner at edges	Thinner at centre, thicker at edges
Behaviour	Converges parallel rays to a point (focus)	Diverges parallel rays (appear to come from focus)
Focal length	Positive (+f)	Negative (-f)
Image - Object at infinity	Real, inverted, highly diminished, at F	Virtual, erect, highly diminished, at F (same side)

Lens Formula & Power

Lens formula1/v - 1/u = 1/f

Power of lens (P)P = 1/f (f in metres); SI unit: Dioptre (D)

Convex lens powerPositive (e.g., +2D)

Concave lens powerNegative (e.g., -2D)

Combination of lensesP = P₁ + P₂ + P₃ + ... (in contact)

Human Eye — Structure & Defects

CorneaTransparent outer layer; provides most of the eye's focusing power

IrisColoured part; controls size of pupil (amount of light entering)

PupilBlack opening; regulates light entry

LensFlexible, can change focal length (accommodation); focuses image on retina

RetinaLight-sensitive layer; rod cells (dim light) + cone cells (colour vision)

Optic nerveCarries visual signals to brain

Myopia (short-sighted)Cannot see distant objects clearly; image forms in front of retina; corrected by concave lens

Hypermetropia (far-sighted)Cannot see near objects clearly; image forms behind retina; corrected by convex lens

PresbyopiaAge-related; difficulty seeing both near and far; corrected by bifocal lens

Near pointClosest distance at which eye can focus clearly = 25 cm

Far pointFarthest distance at which eye can see clearly = Infinity

Dispersion & Rainbow Formation

DispersionSplitting of white light into its constituent colours (VIBGYOR)

CauseDifferent colours travel at different speeds in prism (different refractive indices)

VIBGYORViolet (most bent, highest n) → Indigo → Blue → Green → Yellow → Orange → Red (least bent)

RainbowNatural dispersion caused by water droplets acting as tiny prisms; sun behind observer

Newton's experimentSecond inverted prism recombines VIBGYOR back into white light

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Remember: The power of the human eye is about +60 D (focal length ≈ 1.67 cm). The least distance of distinct vision is 25 cm. A normal eye can see objects clearly from 25 cm to infinity.

Image Formation by Convex Lens — All Cases

Object Position	Image Position	Nature	Size	Application
At infinity	At focus F₂	Real, Inverted	Highly diminished, point-sized	Telescope objective
Beyond 2F₁	Between F₂ and 2F₂	Real, Inverted	Diminished	Camera
At 2F₁	At 2F₂	Real, Inverted	Same size	Photocopier
Between F₁ and 2F₁	Beyond 2F₂	Real, Inverted	Magnified	Projector, microscope objective
At focus F₁	At infinity	Real, Inverted	Highly magnified	Spotlight, searchlight
Between F₁ and optical centre	Same side as object	Virtual, Erect	Magnified	Magnifying glass, simple microscope

Refraction at Curved Surfaces & Applications

Lens maker's equation1/f = (n-1)(1/R₁ - 1/R₂); n = refractive index, R = radius of curvature

Convex lens applicationMagnifying glass, camera lens, microscope objective, telescope, corrective lens for hypermetropia

Concave lens applicationCorrective lens for myopia, peephole in doors, combination with convex lens to correct aberrations

Total internal reflectionUsed in optical fibres (communication), prisms in binoculars, diamonds (sparkle), mirage in deserts

Critical angleAngle of incidence for which angle of refraction = 90°; depends on pair of media

Conditions for TIR1) Light travels from denser to rarer medium, 2) Angle of incidence > critical angle

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Electricity

CLASS 10

Electric Current — Fundamentals

Electric current (I)Rate of flow of electric charge; I = Q/t; SI unit: Ampere (A)

Charge (Q)Fundamental property; SI unit: Coulomb (C); 1 electron charge = 1.6 × 10⁻¹⁹ C

Potential difference (V)Work done per unit charge; V = W/Q; SI unit: Volt (V)

1 Volt1 Joule of work done to move 1 Coulomb of charge between two points

Current directionConventional: +ve to -ve (outside cell); Electron flow: -ve to +ve

Measuring instrumentsAmmeter (current — connected in series), Voltmeter (voltage — connected in parallel)

CircuitClosed path for current flow; open circuit = no current; short circuit = dangerously high current

Ohm's Law & Resistance

Ohm's lawV = IR (voltage = current × resistance); current proportional to voltage at constant temperature

Resistance (R)Property that opposes flow of current; SI unit: Ohm (Ω)

1 OhmResistance when 1V potential difference causes 1A current to flow

Resistivity (ρ)R = ρ(l/A); depends on material; SI unit: Ω·m

Factors affecting R1) Material (resistivity ρ), 2) Length (directly proportional), 3) Cross-section area (inversely proportional), 4) Temperature

Good conductorsLow resistivity (Cu: 1.68 × 10⁻⁸ Ω·m, Al: 2.65 × 10⁻⁸ Ω·m)

Insulators (bad conductors)High resistivity (Rubber, Glass: ~10¹² Ω·m)

Temperature effectResistance of metals increases with temperature (more collisions); semiconductors: decreases

SuperconductorsZero resistance below critical temperature (e.g., Mercury below 4.2 K)

Series & Parallel Circuits

Feature	Series Circuit	Parallel Circuit
Current (I)	Same through all components: I = I₁ = I₂ = I₃	Different in each branch: I = I₁ + I₂ + I₃ (divided)
Voltage (V)	Divided: V = V₁ + V₂ + V₃	Same across each branch: V = V₁ = V₂ = V₃
Equivalent resistance	R_eq = R₁ + R₂ + R₃ (increases)	1/R_eq = 1/R₁ + 1/R₂ + 1/R₃ (decreases)
If one component fails	Circuit breaks, all components stop working	Other branches continue to work independently
Application	Decorative lights (old), fuses	Household wiring, all appliances connected in parallel
Power consumption	Each gets same current (less for high R)	Each gets full voltage (independent control)

Heating Effect of Electric Current

PrincipleWhen current flows through a resistor, electrical energy converts to heat energy

Joule's lawH = I²Rt (Heat produced = current² × resistance × time)

SI unit of heatJoule (J); 1 calorie = 4.18 J

Electric power (P)P = VI = I²R = V²/R; SI unit: Watt (W)

Energy consumedE = P × t = VIt; measured in kWh (1 unit = 1 kWh = 3.6 × 10⁶ J)

Appliances using heatingElectric iron, heater, geyser, toaster, oven, kettle

Filament materialTungsten (high melting point 3380°C, high resistivity)

FuseShort piece of wire with low melting point; melts and breaks circuit when excess current flows

Fuse ratingSlightly higher than normal current; e.g., 5A fuse for 4A appliance

Magnetic Effects of Electric Current

Oersted's experimentCompass needle deflects when placed near current-carrying wire → electricity and magnetism related

Right-hand thumb ruleThumb = current direction; curled fingers = direction of magnetic field lines

SolenoidCoil of wire; produces magnetic field similar to bar magnet when current passes

ElectromagnetSoft iron core inside solenoid; strong temporary magnet (ON with current, OFF without)

Uses of electromagnetElectric bell, cranes (lift scrap iron), MRI machines, relay switches

Fleming's Left-Hand RuleThumb (Force/Motion), Index (Magnetic field), Middle (Current); used for motors

Fleming's Right-Hand RuleThumb (Motion), Index (Magnetic field), Middle (Induced current); used for generators

Electric Motor (DC)

PrincipleForce on current-carrying conductor in magnetic field (Fleming's Left-Hand Rule)

ComponentsArmature (coil), Field magnets (N-S), Split-ring commutator, Brushes, Axle

CommutatorReverses direction of current every half rotation → continuous rotation

ConvertsElectrical energy → Mechanical energy

ApplicationsFans, mixers, washing machines, electric cars, water pumps

Electromagnetic Induction & Generator

Principle (Faraday)Changing magnetic field induces EMF/current in a conductor (electromagnetic induction)

GeneratorConverts mechanical energy → electrical energy

AC GeneratorSlip rings (continuous); current direction changes every half cycle; frequency 50Hz in India

DC GeneratorSplit-ring commutator; current flows in one direction

Difference from motorMotor: current → motion. Generator: motion → current (opposite)

Domestic Electric Circuits — Safety

Component	Function	Details
Live wire (L)	Carries current to appliance	Red/brown wire; 220V (India)
Neutral wire (N)	Completes the circuit; returns current	Black/blue wire; 0V (earth potential)
Earth wire (E)	Safety — carries leaking current to ground	Green wire; connected to metal body of appliance
Fuse/MCB	Breaks circuit if current exceeds safe limit	MCB (Miniature Circuit Breaker) is modern alternative; auto-resets
Switch	On/Off control for a circuit	Always connected in LIVE wire (not neutral) for safety
Earthing	Prevents electric shock from metal body	Third pin in 3-pin plug; connected to earth via ground connection
Short circuit	Live wire touches neutral directly → very high current → fire hazard	Prevented by fuse/MCB

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⚠️ Safety rules: (1) Never touch appliances with wet hands. (2) Switch off before replacing fuse. (3) Always use proper earthing for metal-body appliances. (4) Use MCB instead of wire fuses. (5) Never use wire from live wire as earth wire. (6) Ensure proper insulation of wires.

Important Numerical Formulae — Electricity

Quantity	Formula	SI Unit	Notes
Current (I)	I = Q/t	Ampere (A)	Q = charge in Coulombs, t = time in seconds
Potential diff. (V)	V = W/Q	Volt (V)	W = work done in Joules
Ohm's law	V = IR	—	R = resistance in Ohms (Ω)
Resistance	R = ρl/A	Ohm (Ω)	ρ = resistivity, l = length, A = cross-section area
Series resistance	R_eq = R₁ + R₂ + R₃	Ohm (Ω)	Total resistance increases
Parallel resistance	1/R_eq = 1/R₁ + 1/R₂ + 1/R₃	Ohm (Ω)	Total resistance decreases
Electric power	P = VI = I²R = V²/R	Watt (W)	Rate of energy consumption
Heat energy	H = I²Rt = VIt	Joule (J)	Joule's law of heating
Energy consumed	E = P × t	Joule (J) or kWh	1 kWh = 1 unit = 3.6 × 10⁶ J
Cost of electricity	Cost = E (kWh) × Rate (₹/kWh)	₹	Check electricity bill
Charge on 1 electron	e = 1.6 × 10⁻¹⁹ C	Coulomb (C)	Fundamental unit of charge
Number of electrons	n = Q/e	—	Q = total charge, e = electron charge

Electrical Energy Consumption — Practical Examples

Example: 100W bulb, 5 hrs/day, 30 daysE = 100W × 5h × 30 = 15000 Wh = 15 kWh = 15 units

Cost at ₹5/unitTotal cost = 15 × 5 = ₹75

2000W heater, 2 hrs/day, 30 daysE = 2000 × 2 × 30 = 120000 Wh = 120 kWh = 120 units

1500W iron, 1 hr/day, 30 daysE = 1500 × 1 × 30 = 45000 Wh = 45 kWh = 45 units

Current through 100W bulb (220V)I = P/V = 100/220 = 0.45A

Resistance of 100W bulb (220V)R = V²/P = 220²/100 = 484 Ω

Current through 2kW heater (220V)I = P/V = 2000/220 = 9.09A

Fuse ratingShould be slightly above normal current (e.g., 10A fuse for 9A appliance)

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Environment

CLASS 9–10

Natural Resources — Management & Conservation

Resource	Importance	Conservation Strategies
Water	Essential for all life; drinking, agriculture, industry	Rain water harvesting, drip irrigation, sewage treatment, watershed management, reduce wastage
Soil	Foundation for agriculture; habitat for organisms; water filtration	Prevent erosion (afforestation, contour ploughing, terrace farming), crop rotation, organic farming
Forest	Biodiversity hotspot; oxygen production; climate regulation; carbon sink	Afforestation, sustainable logging, wildlife protection, biosphere reserves, national parks
Coal	Major energy source; used in power plants, steel industry	Use efficiently, switch to renewable energy (solar, wind), develop clean coal technology
Petroleum	Fuel for transport; raw material for plastics, chemicals	Develop electric vehicles, improve fuel efficiency, invest in public transport, biofuels
Natural gas	Cleaner than coal/petrol; used in cooking, electricity	Reduce flaring, efficient distribution (CNG), develop biogas from organic waste
Biodiversity	Ecosystem stability; food security; medicine; ecological balance	Protected areas, biodiversity hotspots, seed banks, anti-poaching laws, habitat restoration

Sustainable Development

DefinitionDevelopment that meets present needs without compromising the ability of future generations to meet their own needs

Brundtland CommissionOur Common Future (1987) — first formal definition of sustainable development

Three pillarsEconomic growth, Social inclusion, Environmental protection

Sustainable practicesRenewable energy, organic farming, water conservation, recycling, public transport

Agenda 21UN action plan for sustainable development (Earth Summit, Rio, 1992)

SDGs17 Sustainable Development Goals (UN, 2015) — No Poverty, Clean Energy, Climate Action, etc.

Pollution — Types & Control Measures

Type	Sources	Effects	Control Measures
Air pollution	Vehicle exhaust, industries, burning, construction dust	Respiratory diseases, acid rain, smog, global warming, crop damage	CNG vehicles, emission standards, scrubbers, electrostatic precipitators, tree plantation
Water pollution	Industrial effluents, sewage, agricultural runoff, oil spills	Waterborne diseases (cholera, typhoid), eutrophication, aquatic death	STP (sewage treatment plants), effluent treatment, reduce fertilizers/pesticides, oil spill cleanup
Soil pollution	Pesticides, chemical fertilizers, industrial waste, plastic, e-waste	Reduced fertility, toxic crops, groundwater contamination	Organic farming, biofertilizers, proper waste disposal, biodegradable materials
Noise pollution	Vehicles, industries, loudspeakers, construction	Hearing loss, stress, sleep disturbance, hypertension	Silencers, noise barriers, restricted zones, green belts, awareness
Thermal pollution	Power plants, industries discharge hot water into water bodies	Reduced dissolved O₂, affects aquatic life	Cooling towers, cooling ponds, use of heated water for space heating
Radioactive pollution	Nuclear power plants, mining, medical waste	Cancer, genetic mutations, birth defects	Proper shielding, safe disposal, remote monitoring, international regulations

Conservation of Wildlife

National parksArea reserved for wildlife; human activity not allowed (e.g., Jim Corbett, Kanha, Gir)

Wildlife sanctuariesArea where animals are protected; some human activity allowed (e.g., Bharatpur)

Biosphere reservesLarge area for biodiversity conservation; includes core + buffer zones (e.g., Nilgiri, Sundarbans)

Endangered speciesSpecies at risk of extinction (e.g., Bengal tiger, Asiatic lion, One-horned rhino)

Red Data BookIUCN publication listing endangered and threatened species

Project TigerLaunched 1973; tiger conservation in India; 50+ tiger reserves

Project ElephantLaunched 1992; elephant corridor and habitat conservation

CITESConvention on International Trade in Endangered Species; regulates wildlife trade

Waste Management — Reduce, Reuse, Recycle

ReduceMinimize waste generation: avoid excess packaging, buy in bulk, use less

ReuseUse items again: cloth bags, refill bottles, donate old items

RecycleProcess waste into new products: paper, glass, metal, plastics

CompostingDecompose organic waste (food, garden waste) into nutrient-rich compost

VermicompostingUsing earthworms to decompose organic waste faster

LandfillDesigned area for solid waste disposal; lined to prevent groundwater contamination

E-wasteElectronic waste (computers, phones); contains toxic metals; needs special recycling

Biomedical wasteMedical waste (syringes, bandages); autoclaved/incinerated for safe disposal

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Sustainable development principle: The three R's — Reduce, Reuse, Recycle — are the cornerstone of waste management. At individual level: carry cloth bags, segregate wet/dry waste, compost kitchen waste, avoid single-use plastics, conserve water and electricity. Every small action contributes to environmental conservation.

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Key Definitions

QUICK REFERENCE

Matter & Chemistry Definitions

Term	Definition
Matter	Anything that occupies space and has mass
Element	A substance made of only one type of atom (cannot be split into simpler substances by chemical means)
Compound	A substance made of two or more elements chemically combined in a fixed ratio
Mixture	Two or more substances physically combined; no fixed ratio
Solution	Homogeneous mixture of two or more substances (solute dissolved in solvent)
Suspension	Heterogeneous mixture; particles are visible and settle down on standing
Colloid	Mixture where particle size is between solution and suspension; shows Tyndall effect
Atom	Smallest unit of an element that retains chemical properties; made of protons, neutrons, electrons
Molecule	Group of two or more atoms chemically bonded together
Mole	Amount of substance containing 6.022 × 10²³ particles (Avogadro's number)
Valency	Combining capacity of an element (number of electrons lost, gained or shared)
Ion	Atom or group of atoms carrying electric charge (cation: +ve, anion: -ve)
Isotope	Atoms of same element with same atomic number but different mass number (different neutrons)
Isobar	Atoms of different elements with same mass number
pH	Measure of hydrogen ion concentration; pH = -log[H⁺]; scale 0-14
Neutralization	Reaction between acid and base to form salt and water
Catalyst	Substance that changes rate of reaction without being consumed
Electrolysis	Chemical decomposition produced by passing electric current through electrolyte
Polymerization	Process of combining many small molecules (monomers) to form a large molecule (polymer)

Physics Definitions

Term	Definition
Speed	Distance travelled per unit time (scalar quantity)
Velocity	Displacement per unit time (vector quantity)
Acceleration	Rate of change of velocity with time
Inertia	Tendency of a body to resist any change in its state of rest or uniform motion
Force	Push or pull; an interaction that changes the state of motion or shape of a body
Momentum	Product of mass and velocity (p = mv); vector quantity
Impulse	Change in momentum; product of force and time (J = FΔt)
Work	Done when force displaces a body in its direction (W = Fs cos θ)
Energy	Capacity to do work; exists as kinetic, potential, thermal, chemical, etc.
Power	Rate of doing work (P = W/t)
Centrifugal force	Apparent outward force on a body moving in a circular path
Gravitation	Force of attraction between any two masses in the universe (F = Gm₁m₂/r²)
Buoyancy	Upward force exerted by a fluid on an immersed object
Specific heat	Amount of heat required to raise temperature of 1 kg substance by 1°C
Latent heat	Heat absorbed/released during phase change without temperature change
Frequency	Number of vibrations per second (Hz)
Wavelength	Distance between two consecutive compressions or rarefactions in a wave
Echo	Reflected sound heard after original sound has stopped (min gap: 0.1 s)

Light & Electricity Definitions

Term	Definition
Reflection	Bouncing back of light from a polished surface
Refraction	Bending of light when it passes from one medium to another
Dispersion	Splitting of white light into its component colours (VIBGYOR)
Focal length	Distance between pole (P) and focus (F) of a mirror/lens
Power of lens	Reciprocal of focal length in metres (P = 1/f); measured in Dioptre (D)
Electric current	Rate of flow of electric charge through a conductor
Potential difference	Work done per unit charge in moving charge between two points
Resistance	Opposition offered by a conductor to the flow of current
Resistivity	Inherent property of a material that resists current flow; independent of dimensions
Ohm's law	At constant temperature, current is directly proportional to potential difference (V = IR)
Electromagnetic induction	Production of EMF/current by changing magnetic field near a conductor
Short circuit	When live wire touches neutral directly → very high current, dangerous
Fuse	Safety device; wire melts and breaks circuit when excess current flows
Domestic circuit	Parallel connection of appliances; each gets same voltage (220V in India)
Concave lens	Diverging lens; thin at centre, thick at edges; always forms virtual, erect, diminished image
Convex lens	Converging lens; thick at centre, thin at edges; can form real or virtual image

Biology Definitions

Term	Definition
Cell	Basic structural and functional unit of all living organisms
Tissue	Group of similar cells performing a specific function
Organ	Group of tissues performing a specific function
Organ system	Group of organs working together for a specific function
Photosynthesis	Process by which green plants make food (glucose) using CO₂, water, and sunlight
Chlorophyll	Green pigment in chloroplasts that absorbs light energy for photosynthesis
Enzyme	Biological catalyst that speeds up biochemical reactions without being consumed
Osmosis	Movement of water molecules from high concentration to low concentration through semi-permeable membrane
Diffusion	Movement of particles from high concentration to low concentration
Transpiration	Loss of water vapour from leaves through stomata
Blood pressure	Force exerted by blood on walls of arteries (normal: 120/80 mmHg)
Neuron	Structural and functional unit of nervous system (nerve cell)
Synapse	Junction between two neurons where signals are transmitted by neurotransmitters
Reflex action	Sudden involuntary response to stimulus; mediated by spinal cord (reflex arc)
Hormone	Chemical messenger secreted by endocrine gland directly into blood
Mitosis	Cell division producing 2 genetically identical daughter cells (growth, repair)
Meiosis	Cell division producing 4 haploid gametes from one diploid cell (sexual reproduction)
Fertilization	Fusion of male gamete (sperm) with female gamete (ovum) to form zygote
Pollination	Transfer of pollen grains from anther to stigma
Ecosystem	Community of living organisms interacting with their physical environment
Food chain	Linear sequence showing transfer of energy from producer to consumer
Biodiversity	Variety of life forms at all levels — genes, species, ecosystems
Adaptation	Structural or behavioural change that helps an organism survive in its environment
Evolution	Gradual change in characteristics of species over many generations
Gene	Unit of heredity; segment of DNA that codes for a specific protein
DNA (Deoxyribonucleic acid)	Molecule that carries genetic instructions; double helix structure
Chromosome	Thread-like structure of DNA and proteins; carries genes (23 pairs in humans)

Environment & Health Definitions

Term	Definition
Biodegradable	Substance that can be decomposed by microorganisms (paper, food waste)
Non-biodegradable	Substance that cannot be decomposed by microorganisms (plastic, glass, DDT)
Eutrophication	Excessive nutrient enrichment of water body causing algal bloom and oxygen depletion
Greenhouse effect	Trapping of heat by greenhouse gases (CO₂, CH₄, N₂O) in Earth's atmosphere
Global warming	Gradual increase in Earth's average surface temperature due to greenhouse gases
Acid rain	Rain with pH less than 5.6 due to SO₂ and NOₓ from fossil fuel burning
Ozone layer	Layer of O₃ in stratosphere that absorbs harmful UV radiation from Sun
Biomagnification	Accumulation of harmful chemicals at increasing concentrations through food chain
Sustainable development	Meeting present needs without compromising ability of future generations
Conservation	Protection and careful management of natural resources and environment
Deforestation	Large-scale removal of forest cover for non-forest use
Afforestation	Planting trees on land that was not previously forested
Red Data Book	Record book of species facing risk of extinction (published by IUCN)
Endemic species	Species found only in a particular geographic area and nowhere else
Migration	Seasonal movement of animals from one region to another
Immunity	Ability of body to resist disease; can be natural or acquired (vaccination)
Vaccine	Preparation of weakened/killed pathogens that provides immunity without causing disease
Pathogen	Disease-causing microorganism (bacteria, virus, fungi, protozoa)
Antibiotic	Medicine that kills or stops growth of bacteria (e.g., Penicillin)
Vector	Organism that carries disease-causing pathogen from one host to another (e.g., mosquito)

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Exam tip: For board exams, always write definitions with proper scientific terms. Mention the law, formula, and SI units wherever applicable. For numerical problems, always show the formula substitution step clearly. Draw neat labelled diagrams for anatomy-based questions (heart, nephron, brain, human eye, etc.).

Important Laws & Principles — Quick Reference

Law / Principle	Scientist	Statement / Formula	Application
Law of conservation of mass	Lavoisier	Mass can neither be created nor destroyed in a chemical reaction	Balancing chemical equations
Law of definite proportions	Proust	A chemical compound always contains same elements in same proportion by mass	Water = H:O = 1:8 by mass always
Law of multiple proportions	Dalton	When two elements form more than one compound, ratios of mass are small whole numbers	CO and CO₂ — O ratio 1:2
Newton's 1st Law	Isaac Newton	Object remains at rest or in uniform motion unless acted upon by external force (Inertia)	Seatbelts, headrest, falling forward in bus
Newton's 2nd Law	Isaac Newton	F = ma; force equals mass times acceleration	Rocket thrust, elevator, vehicle dynamics
Newton's 3rd Law	Isaac Newton	Every action has equal and opposite reaction	Walking, swimming, recoil of gun
Law of universal gravitation	Newton	F = Gm₁m₂/r²; every mass attracts every other mass	Planetary motion, tides, satellite orbits
Law of conservation of energy	Various	Energy can neither be created nor destroyed, only transformed	Pendulum, roller coaster, power plants
Law of conservation of momentum	Various	Total momentum of isolated system remains constant before and after collision	Gun recoil, billiard balls, rocket propulsion
Ohm's law	Georg Ohm	V = IR; potential difference is proportional to current at constant temperature	Circuit analysis, calculating R, V, I
Snell's law of refraction	Willebrord Snellius	n₁ sin i = n₂ sin r	Lens design, optical fibres, prisms
Archimedes' principle	Archimedes	Buoyant force = Weight of fluid displaced	Ships, submarines, hot air balloons

Important Constants & Values for Numerical Problems

Constant	Symbol	Value	Unit	Used In
Speed of light	c	3 × 10⁸	m/s	Optics, refraction
Gravitational constant	G	6.674 × 10⁻¹¹	N·m²/kg²	Gravitation
Acceleration due to gravity	g	9.8 (≈ 10)	m/s²	Free fall, weight, projectiles
Avogadro's number	Nₐ	6.022 × 10²³	/mol	Mole concept, atoms, molecules
Electron charge	e	1.6 × 10⁻¹⁹	C	Electricity, electrostatics
Speed of sound in air	v	344 (≈ 340)	m/s	Sound, echo, SONAR
Planck's constant	h	6.626 × 10⁻³⁴	J·s	Quantum physics (Class 11+)
Atomic mass unit	u	1.66 × 10⁻²⁴	g	Atomic/molecular mass
Latent heat of ice	Lf	3.34 × 10⁵	J/kg	Calorimetry
Latent heat of steam	Lv	2.26 × 10⁶	J/kg	Calorimetry
Specific heat of water	s	4186	J/(kg·°C)	Calorimetry
Domestic voltage (India)	V	220	V (Volts)	Electricity numericals

Important Chemical Reactions to Remember

Reaction	Equation	Type	Significance
Rusting of iron	4Fe + 3O₂ + 2xH₂O → 2Fe₂O₃·xH₂O	Slow oxidation (corrosion)	Damage to iron structures; prevented by painting, galvanizing
Thermal decomposition of limestone	CaCO₃ →(heat)→ CaO + CO₂	Decomposition (endothermic)	Manufacture of quicklime (CaO) in cement industry
Photosynthesis	6CO₂ + 6H₂O →(sunlight, chlorophyll)→ C₆H₁₂O₆ + 6O₂	Endothermic (light energy absorbed)	Basis of all food chains; produces oxygen
Respiration	C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy	Exothermic (energy released)	Provides energy for all life processes
Neutralization	HCl + NaOH → NaCl + H₂O	Acid + Base → Salt + Water	Antacids, soil treatment, industrial processes
Baking soda + acid	NaHCO₃ + HCl → NaCl + H₂O + CO₂	Gas evolution	Cooking (cakes rise), antacid action
Fermentation (anaerobic)	C₆H₁₂O₆ →(yeast)→ 2C₂H₅OH + 2CO₂	Decomposition	Production of ethanol (alcohol) and CO₂
Corrosion prevention (galvanizing)	Zn → Zn²⁺ + 2e⁻ (zinc oxidizes first)	Oxidation	Protects iron from rusting; zinc sacrificially corrodes
Chlor-alkali process	2NaCl(aq) + 2H₂O →(electricity)→ 2NaOH + Cl₂ + H₂	Electrolysis	Produces NaOH, Cl₂, and H₂ industrially
Bleaching powder + acid	Ca(OCl)₂ + 2HCl → CaCl₂ + 2H₂O + Cl₂	Displacement	Releases chlorine for bleaching and disinfection

Diseases & Their Causes — Quick Reference

Disease	Pathogen / Cause	Transmission	Prevention
Malaria	Plasmodium (protozoan)	Female Anopheles mosquito bite	Mosquito nets, repellent, antimalarial drugs, drain stagnant water
Dengue	Dengue virus	Female Aedes aegypti mosquito bite	Prevent mosquito breeding, clean water storage
Cholera	Vibrio cholerae (bacteria)	Contaminated water and food	Clean drinking water, proper sanitation, ORS
Typhoid	Salmonella typhi (bacteria)	Contaminated water and food	Vaccination (Typhoid), clean water, hygiene
Tuberculosis (TB)	Mycobacterium tuberculosis	Airborne droplets (cough, sneeze)	BCG vaccine, proper ventilation, DOTS treatment
Polio	Poliovirus	Contaminated water, faecal-oral route	Oral polio vaccine (OPV drops), pulse polio program
Rabies	Rabies virus	Bite of infected animal (dog, bat)	Anti-rabies vaccine after animal bite, pet vaccination
HIV/AIDS	HIV (Human Immunodeficiency Virus)	Blood transfusion, sexual contact, mother to child	Safe practices, blood screening, no needle sharing
COVID-19	SARS-CoV-2 (coronavirus)	Airborne droplets, contact	Vaccination, masks, social distancing, hand hygiene
Ringworm	Fungi (Microsporum)	Contact with infected person, towels	Antifungal creams, personal hygiene

SI Units — Quick Reference Table

Quantity	SI Unit	Symbol	Other Common Units
Length	metre	m	cm, mm, km
Mass	kilogram	kg	g, mg, tonne
Time	second	s	min, hr
Temperature	Kelvin	K	°C (Celsius), °F (Fahrenheit)
Electric current	Ampere	A	mA, μA
Force	Newton	N	kgf, dyne
Energy / Work	Joule	J	cal, kcal, eV, kWh
Power	Watt	W	kW, HP (horsepower)
Pressure	Pascal	Pa	atm, bar, mmHg
Frequency	Hertz	Hz	kHz, MHz
Electric charge	Coulomb	C	e (electron charge)
Potential difference	Volt	V	mV, kV
Resistance	Ohm	Ω	kΩ, MΩ

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