General Science — Physics, Chemistry, Biology (up to 10th CBSE level)

Part A: Physics

Units and Measurement

• SI base units: Length (metre), Mass (kilogram), Time (second), Temperature (kelvin), Electric Current (ampere), Luminous Intensity (candela), Amount of Substance (mole).
• Common instruments: Barometer (atmospheric pressure), Thermometer (temperature), Hygrometer (humidity), Anemometer (wind speed), Seismograph (earthquakes), Odometer (distance travelled by vehicle), Sphygmomanometer (blood pressure), Lactometer (purity of milk).

Mechanics

• Newton's Laws of Motion:
  1. First Law (Inertia): a body remains at rest/uniform motion unless acted upon by a net external force.
  2. Second Law: F = ma (Force = mass × acceleration).
  3. Third Law: for every action, there is an equal and opposite reaction.
• Gravitation: Newton's Law of Universal Gravitation — F = G(m1m2)/r². Value of g (acceleration due to gravity) on Earth ≈ 9.8 m/s².
• Work, Energy, Power: Work = Force × Distance; SI unit of Work/Energy = Joule; SI unit of Power = Watt.
• Kinetic Energy = ½mv²; Potential Energy = mgh.
• Law of Conservation of Energy: energy can neither be created nor destroyed, only transformed.

Heat and Thermodynamics

• Heat transfer modes: Conduction (solids), Convection (fluids), Radiation (no medium needed, e.g. sunlight).
• Temperature scales: Celsius, Fahrenheit, Kelvin (absolute zero = 0K = -273.15°C).
• Specific heat capacity: amount of heat needed to raise temperature of 1 kg substance by 1°C. Water has high specific heat.

Light (Optics)

• Reflection: angle of incidence = angle of reflection.
• Refraction: bending of light when passing between media of different densities (governed by Snell's Law).
• Convex lens: converges light, used to correct hypermetropia (long-sightedness), used in magnifying glasses/telescopes.
• Concave lens: diverges light, corrects myopia (short-sightedness).
• Human eye defects: Myopia (near-sightedness, corrected by concave lens), Hypermetropia (far-sightedness, corrected by convex lens), Presbyopia (age-related), Astigmatism.
• Rainbow formation: dispersion, refraction and total internal reflection of sunlight in raindrops; VIBGYOR order (Violet, Indigo, Blue, Green, Yellow, Orange, Red).
• Scattering of light: explains blue colour of sky (Rayleigh scattering) and red colour of sun at sunrise/sunset.

Electricity and Magnetism

• Ohm's Law: V = IR (Voltage = Current × Resistance).
• SI unit of current: Ampere; Resistance: Ohm; Voltage: Volt; Charge: Coulomb.
• Conductors (allow current flow — metals) vs Insulators (do not — rubber, glass, wood).
• Fleming's Left-Hand Rule: direction of force on current-carrying conductor in a magnetic field (motors).
• Fleming's Right-Hand Rule: direction of induced current (generators).
• Devices: Generator (mechanical → electrical energy), Motor (electrical → mechanical), Transformer (changes AC voltage).

Sound

• Sound needs a medium to travel (cannot travel in vacuum); travels fastest in solids, slowest in gases.
• Speed of sound in air ≈ 343 m/s at room temperature.
• Ultrasound: frequency above 20,000 Hz, used in SONAR, medical imaging.
• Audible range for humans: 20 Hz to 20,000 Hz.

Modern Physics / Important Discoveries

• Atomic structure: Electron (J.J. Thomson, 1897), Proton (Ernest Rutherford), Neutron (James Chadwick, 1932), Nucleus (Rutherford's gold foil experiment).
• Radioactivity: discovered by Henri Becquerel; studied by Marie Curie and Pierre Curie.
• Theory of Relativity: Albert Einstein.
• Laws of Motion & Gravitation: Isaac Newton.

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Part B: Chemistry

Matter and States

• Three states of matter: Solid, Liquid, Gas (plus Plasma as 4th state).
• Changes of state: Melting, Freezing, Evaporation, Condensation, Sublimation (solid directly to gas, e.g., camphor, dry ice/CO₂), Deposition.

Atomic Structure & Periodic Table

• Modern Periodic Table: arranged by increasing atomic number, developed by Henry Moseley (based on Mendeleev's earlier work by atomic mass).
• Elements grouped into 18 Groups and 7 Periods.
• Noble gases (Group 18): Helium, Neon, Argon, Krypton, Xenon, Radon — inert/unreactive.
• Alkali metals (Group 1): Lithium, Sodium, Potassium — highly reactive.
• Halogens (Group 17): Fluorine, Chlorine, Bromine, Iodine.

Chemical Bonding & Reactions

• Ionic bond: transfer of electrons (e.g., NaCl).
• Covalent bond: sharing of electrons (e.g., H₂O, CO₂).
• Types of reactions: Combination, Decomposition, Displacement, Double Displacement, Oxidation-Reduction (Redox).
• pH scale: 0-14; measures acidity/alkalinity. pH < 7 = acidic, pH = 7 neutral (pure water), pH > 7 = basic/alkaline.

Acids, Bases & Salts

• Common acids: Hydrochloric acid (HCl — present in stomach), Sulphuric acid (H₂SO₄), Nitric acid (HNO₃), Acetic acid (vinegar), Citric acid (citrus fruits).
• Common bases: Sodium hydroxide (NaOH, caustic soda), Ammonium hydroxide.
• Common salts: Sodium chloride (NaCl, common salt), Sodium bicarbonate (baking soda), Calcium carbonate (limestone/chalk/marble).

Metals and Non-metals

• Metals: good conductors, malleable, ductile, lustrous (Gold, Silver, Copper, Iron, Aluminium).
• Non-metals: poor conductors (except graphite), brittle (Carbon, Sulphur, Oxygen, Nitrogen).
• Metalloids: properties of both — Silicon, Boron, Germanium, Arsenic.
• Most abundant metal in Earth's crust: Aluminium. Most abundant element in Earth's crust overall: Oxygen.
• Most malleable/ductile metal: Gold. Best conductor of electricity: Silver (Copper is 2nd, most commonly used practically).
• Liquid metal at room temperature: Mercury. Liquid non-metal at room temperature: Bromine.

Carbon Compounds

• Allotropes of carbon: Diamond (hardest natural substance), Graphite (soft, conducts electricity, used in pencils), Fullerene, Graphene.
• Hydrocarbons: basis of organic chemistry, fuels (petrol, diesel, LPG, CNG).

Everyday Chemistry

• Rusting: iron + oxygen + moisture → iron oxide; prevented by galvanising, painting, alloying.
• Hard water: contains calcium/magnesium salts, doesn't lather soap easily.
• Common alloys: Steel (Iron + Carbon), Stainless Steel (Iron + Chromium + Nickel), Bronze (Copper + Tin), Brass (Copper + Zinc), Amalgam (mercury + another metal).

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Part C: Biology / Life Science

Cell Biology

• Cell: basic structural and functional unit of life — discovered by Robert Hooke (1665, in cork).
• Cell Theory: proposed by Schleiden and Schwann.
• Types: Prokaryotic (no defined nucleus — bacteria) and Eukaryotic (defined nucleus — plants, animals).
• Key organelles: Nucleus (control centre, contains DNA), Mitochondria ("powerhouse of the cell," site of respiration/ATP production), Chloroplast (site of photosynthesis, in plants), Ribosomes (protein synthesis), Golgi apparatus (packaging/secretion).

Human Body Systems

• Digestive System: mouth → oesophagus → stomach → small intestine (main absorption) → large intestine → rectum. Liver (largest gland, produces bile) and pancreas (produces insulin & digestive enzymes) are accessory organs.
• Respiratory System: nose → trachea → bronchi → lungs (alveoli — gas exchange site).
• Circulatory System: Heart (4 chambers — 2 atria, 2 ventricles) pumps blood; discovered circulation by William Harvey. Blood components: Plasma, RBC (oxygen transport, contains haemoglobin, made in bone marrow), WBC (immunity), Platelets (clotting).
• Blood groups: A, B, AB, O system (discovered by Karl Landsteiner); Rh factor.
• Nervous System: Brain (Cerebrum — largest part, thinking; Cerebellum — balance/coordination; Medulla oblongata — controls involuntary actions like heartbeat, breathing), Spinal cord, Neurons (nerve cells).
• Skeletal System: 206 bones in adult human body; Femur (thigh) — largest bone; Stapes (ear) — smallest bone.
• Endocrine System: glands secreting hormones — Pituitary ("master gland"), Thyroid (thyroxine, metabolism), Pancreas (insulin, blood sugar regulation), Adrenal (adrenaline).
• Excretory System: Kidneys (filter blood, form urine), Ureters, Bladder, Urethra.

Genetics

• Father of Genetics: Gregor Mendel (pea plant experiments — laws of inheritance).
• DNA: double helix structure discovered by James Watson and Francis Crick (1953); carries genetic information.
• Human chromosome number: 46 (23 pairs); sex determined by X and Y chromosomes (XX = female, XY = male).

Plant Biology

• Photosynthesis: 6CO₂ + 6H₂O + sunlight → C₆H₁₂O₆ (glucose) + 6O₂; occurs in chloroplasts, requires chlorophyll.
• Respiration in plants: occurs continuously, opposite of photosynthesis in gas exchange.
• Plant tissues: Xylem (transports water upward), Phloem (transports food).

Diseases (very frequently asked)

Disease	Causative Agent	Type
Malaria	Plasmodium (via female Anopheles mosquito)	Protozoan
Dengue	Dengue virus (via Aedes aegypti mosquito)	Viral
Tuberculosis (TB)	Mycobacterium tuberculosis	Bacterial
Typhoid	Salmonella typhi	Bacterial
Cholera	Vibrio cholerae	Bacterial
COVID-19	SARS-CoV-2	Viral
AIDS	HIV (Human Immunodeficiency Virus)	Viral
Chickenpox	Varicella-zoster virus	Viral
Rabies	Rabies virus (via animal bites)	Viral
Polio	Poliovirus	Viral

• Vitamins and Deficiency Diseases:
  • Vitamin A (Retinol) — deficiency causes Night Blindness; sources: carrots, liver.
  • Vitamin B1 (Thiamine) — deficiency causes Beriberi.
  • Vitamin C (Ascorbic acid) — deficiency causes Scurvy; sources: citrus fruits.
  • Vitamin D (Calciferol) — deficiency causes Rickets (children)/Osteomalacia (adults); source: sunlight.
  • Vitamin K — needed for blood clotting.
  • Discovered by: Funk (coined term "Vitamine").

Classification of Living Organisms

• Carl Linnaeus: "Father of Taxonomy," binomial nomenclature system.
• Five Kingdom Classification (R.H. Whittaker): Monera, Protista, Fungi, Plantae, Animalia.