Complete General Science (Physics + Chemistry + Biology) for UPSC, SSC, Railways, Law Entrance and other competitive Exams

PART 1: PHYSICS

1. Units and Measurements

Important SI Units

Important Measuring Instruments

• Barometer – Atmospheric pressure.

• Thermometer – Temperature.

• Hygrometer – Humidity.

• Anemometer – Wind speed.

• Ammeter – Electric current.

• Voltmeter – Potential difference.

• Galvanometer – Small electric current.

• Hydrometer – Relative density of liquids.

• Lactometer – Purity/specific gravity of milk.

• Seismograph – Earthquake vibrations.

• Spherometer – Curvature of spherical surfaces.

• Manometer – Pressure of gases.

• Altimeter – Altitude.

• Odometer – Distance travelled by vehicle.

• Speedometer – Speed of vehicle.

• Calorimeter – Heat measurement.

2. Motion

• Distance: Total path travelled.

• Displacement: Shortest distance between initial and final positions.

• Speed = Distance / Time.

• Velocity = Displacement / Time.

• Acceleration = Change in velocity / Time.

• Uniform motion: Equal distances in equal time intervals.

• Retardation: Negative acceleration.

Equations of Motion:

1. \(v=u+at\)

2. \(s=ut+\frac12 at^2\)

3. \(v^2=u^2+2as\)

Where:

• u = Initial velocity

• v = Final velocity

• a = Acceleration

• t = Time

• s = Displacement

3. Newton’s Laws of Motion

1. First Law (Law of Inertia): A body remains at rest or in uniform motion unless acted upon by an external force.

2. Second Law: Force = Mass × Acceleration (F = ma).

3. Third Law: Every action has an equal and opposite reaction.

• Momentum = Mass × Velocity.

• Impulse = Change in momentum.

• SI unit of force = Newton.

Examples:

• Passengers fall forward when a bus stops suddenly – Inertia.

• Rocket propulsion – Newton’s Third Law.

• Walking – Action and reaction.

4. Work, Energy and Power

• Work = Force × Displacement (in the direction of force).

• SI unit of work = Joule.

• Energy = Capacity to do work.

• Power = Work / Time.

• SI unit of power = Watt.

Types of Energy

• Kinetic Energy = \(\frac12 mv^2\)

• Potential Energy = mgh

• Heat Energy

• Chemical Energy

• Electrical Energy

• Nuclear Energy

• Solar Energy

Law of Conservation of Energy: Energy can neither be created nor destroyed; it can only be transformed.

• 1 Horsepower ≈ 746 Watt.

• 1 kWh = 3.6 × 10⁶ Joules.

• Commercial unit of electrical energy = kWh.

5. Gravitation

• Every object attracts every other object.

• Universal gravitational constant (G) = 6.67 × 10⁻¹¹ Nm²/kg².

• Acceleration due to gravity (g) ≈ 9.8 m/s².

• Weight = Mass × Gravity.

• Mass remains constant everywhere; weight changes with gravity.

• Weight on the Moon = 1/6 of weight on Earth.

• Escape velocity of Earth ≈ 11.2 km/s.

• Earth rotates from west to east.

Important Facts

• Gravitational force is always attractive.

• Planets revolve around the Sun due to gravitational force.

• Tides are mainly caused by the gravitational pull of the Moon and Sun.

• An object in free fall experiences weightlessness (apparent weight zero).

6. Pressure and Fluid Mechanics

• Pressure = Force / Area.

• SI unit = Pascal.

• Pressure increases with depth in a liquid.

• Hydraulic lift works on Pascal’s Law.

• Floating of ships is based on Archimedes’ Principle.

• Hydrometer works on the principle of flotation.

• Relative density has no unit.

• Atmospheric pressure is measured by a barometer.

Archimedes’ Principle: An immersed body experiences an upward buoyant force equal to the weight of the displaced fluid.

7. Heat and Temperature

• Heat is a form of energy.

• Temperature measures the degree of hotness or coldness.

• SI unit of temperature = Kelvin.

• Heat transfer takes place by:

  1. Conduction – Mainly in solids.

  2. Convection – Mainly in liquids and gases.

  3. Radiation – Does not require a medium.

Important Facts

• Water has maximum density at 4°C.

• Normal human body temperature ≈ 37°C or 98.6°F.

• Absolute zero = −273.15°C.

• Clinical thermometer measures body temperature.

• Sea breeze blows from sea to land during the day.

• Land breeze blows from land to sea at night.

• Black surfaces are good absorbers and emitters of heat.

• White surfaces are good reflectors of heat.

Temperature Conversion

8. Sound

• Sound is produced by vibrations.

• Sound requires a material medium.

• Sound cannot travel through a vacuum.

• Sound travels fastest in solids and generally slowest in gases.

• Speed of sound in air at 20°C ≈ 343 m/s.

• Human audible range = 20 Hz to 20,000 Hz.

Important Facts

• SONAR uses ultrasonic waves.

• Echo is caused by reflection of sound.

• Pitch depends on frequency.

• Loudness depends mainly on amplitude.

• Quality (timbre) distinguishes sounds from different sources.

• Bats use ultrasonic waves for navigation.

• Dolphins use echolocation.

9. Light

• Light travels in a straight line in a homogeneous medium.

• Speed of light in vacuum = 3 × 10⁸ m/s.

• Light is an electromagnetic wave.

• Reflection – Bouncing back of light.

• Refraction – Bending of light when it changes medium.

• Dispersion – Splitting of white light into seven colours.

Mirrors

• Concave mirror can form real or virtual images.

• Convex mirror always forms virtual, erect and diminished images.

• Rear-view mirrors provide a wider field of view.

Lenses

• Convex lens – Converging lens.

• Concave lens – Diverging lens.

• Convex lens is used to correct hypermetropia.

• Concave lens is used to correct myopia.

Important Optical Phenomena

• Rainbow – Dispersion and refraction of sunlight with internal reflection in water droplets.

• Blue sky – Rayleigh scattering.

• Red colour at sunrise/sunset – Scattering.

• Twinkling of stars – Atmospheric refraction.

• Mirage – Refraction and total internal reflection.

• Optical fibre – Total internal reflection.

• White light consists of VIBGYOR.

10. Electricity and Magnetism

Electricity

• Electric current = Charge / Time.

• SI unit = Ampere.

• Potential difference = Volt.

• Resistance = Ohm.

• Electric power = VI.

• Ohm’s Law: V = IR.

Resistance

• Series combination: R = R₁ + R₂ + R₃.

• Parallel combination: 1/R = 1/R₁ + 1/R₂ + 1/R₃.

Important Facts

• Copper and aluminium are good conductors.

• Rubber and plastic are insulators.

• Fuse wire has a low melting point.

• Electric fuse is connected in series.

• Domestic appliances are connected in parallel.

• AC changes direction periodically.

• DC flows in one direction.

• India uses AC supply of 50 Hz.

• Electric energy is measured in kWh.

Magnetism

• Like poles repel; unlike poles attract.

• Earth behaves approximately like a giant magnet.

• Electromagnets are made using current-carrying coils.

• Electric motor converts electrical energy into mechanical energy.

• Electric generator converts mechanical energy into electrical energy.

• Transformer works on electromagnetic induction.

• A transformer generally works with AC.

11. Modern Physics

• Atom consists of protons, neutrons and electrons.

• Electron – Negatively charged.

• Proton – Positively charged.

• Neutron – No charge.

• Nucleus contains protons and neutrons.

Important Discoveries

Radioactivity

• Alpha particles – Positively charged, low penetration.

• Beta particles – High-speed electrons or positrons.

• Gamma rays – Electromagnetic radiation, high penetration.

• Nuclear fission – Splitting of a heavy nucleus.

• Nuclear fusion – Joining of light nuclei.

• Sun produces energy through nuclear fusion.

Electromagnetic Spectrum

Order of increasing frequency:

Radio → Microwave → Infrared → Visible → Ultraviolet → X-rays → Gamma rays.

PART 2: CHEMISTRY

1. Basic Concepts

• Matter has mass and occupies space.

• Three common states: Solid, Liquid and Gas.

• Atom is the smallest unit of an element that retains its chemical properties.

• Molecule consists of two or more atoms chemically bonded.

• Element contains one type of atom.

• Compound contains two or more elements chemically combined in a fixed proportion.

• Mixture contains substances physically combined.

Types of Mixtures

• Homogeneous – Uniform composition.

• Heterogeneous – Non-uniform composition.

• Solution – Solute + Solvent.

• Suspension – Particles settle on standing.

• Colloid – Particles do not settle easily.

2. Atomic Structure

• Atomic number = Number of protons.

• Mass number = Protons + Neutrons.

• Isotopes – Same atomic number, different mass numbers.

• Isobars – Same mass number, different atomic numbers.

• Isotones – Same number of neutrons.

Examples:

• Hydrogen isotopes: Protium, Deuterium, Tritium.

• Carbon-12 and Carbon-14 – Isotopes.

• Carbon-14 is used in radiocarbon dating.

3. Periodic Table

• Modern periodic law is based on atomic number.

• Modern periodic table has 7 periods and 18 groups.

• Elements in the same group generally have similar chemical properties.

• Metals are mainly on the left and centre.

• Non-metals are mainly on the right.

• Metalloids have properties of both metals and non-metals.

Important Groups

Important Elements

• Hydrogen – Lightest element.

• Helium – Lightest noble gas.

• Lithium – Lightest metal.

• Mercury – Liquid metal at room temperature.

• Bromine – Liquid non-metal at room temperature.

• Tungsten – Very high melting point.

• Carbon – Basis of organic chemistry.

• Silicon – Important semiconductor.

4. Chemical Bonding

• Ionic bond – Transfer of electrons.

• Covalent bond – Sharing of electrons.

• Metallic bond – Attraction between metal ions and delocalised electrons.

• Electrovalent compounds generally have high melting and boiling points.

• Covalent compounds generally have lower melting and boiling points.

Examples:

• NaCl – Ionic bond.

• H₂O – Covalent bond.

• CH₄ – Covalent bond.

5. Acids, Bases and Salts

Acids

• Sour in taste.

• Turn blue litmus red.

• pH less than 7.

• Release H⁺ ions in aqueous solution.

Examples:

• HCl – Hydrochloric acid.

• H₂SO₄ – Sulphuric acid.

• HNO₃ – Nitric acid.

• CH₃COOH – Acetic acid.

• H₂CO₃ – Carbonic acid.

Bases

• Bitter in taste and often slippery.

• Turn red litmus blue.

• pH greater than 7.

• Produce OH⁻ ions in aqueous solution.

Examples:

• NaOH – Sodium hydroxide.

• KOH – Potassium hydroxide.

• Ca(OH)₂ – Calcium hydroxide.

• Mg(OH)₂ – Magnesium hydroxide.

pH Scale

• Pure water has pH 7 at 25°C.

• Human blood pH is approximately 7.35–7.45.

• Tooth decay begins to accelerate when mouth pH falls below approximately 5.5.

Important Salts

6. Metals and Non-Metals

Metals

• Generally lustrous.

• Malleable and ductile.

• Good conductors of heat and electricity.

• Generally form positive ions.

• Examples: Iron, copper, aluminium, zinc, gold, silver.

Non-Metals

• Generally poor conductors.

• Generally brittle in solid form.

• Often form negative ions or covalent bonds.

• Examples: Oxygen, nitrogen, sulphur, phosphorus, carbon.

Important Alloys

Corrosion

• Rusting of iron requires oxygen and moisture.

• Rust is hydrated iron(III) oxide.

• Galvanisation – Coating iron/steel with zinc.

• Stainless steel resists corrosion due to a protective oxide layer.

7. Chemical Reactions

Important types:

1. Combination reaction.

2. Decomposition reaction.

3. Displacement reaction.

4. Double displacement reaction.

5. Oxidation reaction.

6. Reduction reaction.

7. Neutralisation reaction.

Important Definitions

• Oxidation – Loss of electrons or increase in oxidation state.

• Reduction – Gain of electrons or decrease in oxidation state.

• Catalyst – Changes reaction rate without being consumed overall.

• Exothermic reaction – Releases heat.

• Endothermic reaction – Absorbs heat.

8. Important Gases

Important Facts

• Air contains approximately 78% nitrogen and 21% oxygen.

• CO₂ is a greenhouse gas.

• CO binds strongly to haemoglobin.

• Ozone layer protects Earth from harmful UV radiation.

• Dry ice = Solid CO₂.

• LPG mainly contains propane and butane.

• CNG mainly contains methane.

• Biogas mainly contains methane and carbon dioxide.

9. Carbon and Its Compounds

• Carbon atomic number = 6.

• Valency = 4.

• Shows catenation (self-linking property).

• Diamond – Hardest naturally occurring mineral.

• Graphite – Conducts electricity.

• Fullerene – Allotropic form of carbon.

• Graphene – Single layer of carbon atoms.

Important Organic Compounds

Important Facts

• Alcohol is used as a solvent and fuel.

• Ethanol is the alcohol present in alcoholic beverages.

• Vinegar contains dilute acetic acid.

• Fermentation of sugar produces ethanol and CO₂.

• Soap is generally a sodium or potassium salt of fatty acids.

• Detergents work in hard water better than ordinary soap.

10. Chemistry in Everyday Life

• Antacid – Neutralises excess stomach acid.

• Baking soda – Used in baking and as an antacid.

• Washing soda – Used for cleaning and softening hard water.

• Bleaching powder – Disinfection and bleaching.

• Teflon – Non-stick coating.

• PVC – Pipes and insulation.

• Bakelite – Electrical switches.

• Nylon – Synthetic fibre.

• Rayon – Regenerated cellulose fibre.

• Polyester – Synthetic fibre.

• Urea – Nitrogen fertiliser.

PART 3: BIOLOGY

1. Cell Biology

• Cell is the basic structural and functional unit of life.

• Robert Hooke discovered cells in 1665.

• Leeuwenhoek observed living microorganisms.

• Schleiden and Schwann proposed cell theory.

• Virchow stated that all cells arise from pre-existing cells.

Cell Organelles

Important Facts:

• Mitochondria are called the powerhouse of the cell.

• Ribosomes are called protein factories.

• Lysosomes are called suicide bags.

• Chloroplast contains chlorophyll.

• Prokaryotes lack a membrane-bound nucleus.

• Eukaryotes have a membrane-bound nucleus.

2. Plant and Animal Cells

3. Human Digestive System

Pathway:

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

Important Organs and Functions

• Mouth – Chewing and salivary digestion.

• Salivary glands – Produce saliva containing amylase.

• Stomach – Secretes HCl and digestive enzymes.

• Liver – Produces bile.

• Gallbladder – Stores bile.

• Pancreas – Produces digestive enzymes and hormones.

• Small intestine – Main site of digestion and nutrient absorption.

• Large intestine – Absorbs water and electrolytes.

Digestive Enzymes

• Amylase – Breaks starch.

• Pepsin – Digests proteins.

• Trypsin – Digests proteins.

• Lipase – Digests fats.

• Maltase – Converts maltose into glucose.

4. Human Respiratory System

• Main organ – Lungs.

• Gas exchange occurs in alveoli.

• Oxygen is transported mainly by haemoglobin.

• Carbon dioxide is transported mainly as bicarbonate ions in blood.

• Diaphragm helps in breathing.

• Normal adult breathing rate at rest is approximately 12–20 breaths/minute.

Important Facts:

• Right lung has 3 lobes.

• Left lung has 2 lobes.

• Humans have 23 pairs of chromosomes.

• Haemoglobin contains iron.

• Respiration releases energy in the form of ATP.

5. Circulatory System

• Blood is a fluid connective tissue.

• Human heart has four chambers.

• Right atrium, right ventricle, left atrium, left ventricle.

• Arteries carry blood away from the heart.

• Veins carry blood towards the heart.

• Capillaries allow exchange of materials.

Components of Blood

Important Facts

• RBCs contain haemoglobin.

• Mature human RBCs lack a nucleus.

• WBCs protect the body from infections.

• Platelets help in clotting.

• Universal RBC donor (for red-cell transfusion) – O negative.

• Universal RBC recipient – AB positive.

• Normal blood pH – 7.35–7.45.

• Average adult resting heart rate – Approximately 60–100 beats/minute.

6. Excretory System

• Main organs – Kidneys.

• Functional unit of kidney – Nephron.

• Kidneys remove nitrogenous wastes.

• Urea is the main nitrogenous waste in human urine.

• Urine is stored in urinary bladder.

• Ureters carry urine from kidneys to bladder.

• Urethra carries urine out of the body.

7. Nervous System

• Brain and spinal cord form the central nervous system.

• Peripheral nerves form the peripheral nervous system.

• Neuron is the structural and functional unit of the nervous system.

Parts of Brain

• Reflex action is a rapid, automatic response.

• Spinal cord controls many reflex actions.

• Insulin is secreted by the pancreas.

8. Endocrine System and Hormones

Important Facts:

• Pituitary is traditionally called the master gland.

• Iodine deficiency can cause goitre.

• Insulin deficiency or resistance is associated with diabetes mellitus.

• Adrenaline is known as the emergency hormone.

9. Vitamins and Deficiency Diseases

Important Facts

• Vitamin A – Vision.

• Vitamin B complex – Metabolism and nervous system functions.

• Vitamin C – Collagen formation.

• Vitamin D – Calcium absorption.

• Vitamin E – Antioxidant.

• Vitamin K – Blood clotting.

• Vitamin D is also called the sunshine vitamin.

• Vitamins A, D, E and K are fat-soluble.

• Vitamins B and C are water-soluble.

10. Diseases and Causative Organisms

Important Disease Vectors

11. Nutrition

Major Nutrients

Important Facts

• Carbohydrates and fats are major energy sources.

• Protein is called the body-building nutrient.

• Glucose is a simple sugar.

• Starch is a complex carbohydrate.

• Haemoglobin requires iron.

• Calcium is essential for bones and teeth.

• Iodine is essential for thyroid hormone synthesis.

12. Plant Biology

Photosynthesis

• Takes place mainly in chloroplasts.

• Chlorophyll absorbs light energy.

• Plants use CO₂ and water to produce carbohydrates and oxygen.

Important Facts

• Photosynthesis occurs mainly in leaves.

• Stomata help in gas exchange.

• Xylem transports water and minerals.

• Phloem transports food.

• Root hairs absorb water.

• Transpiration is the loss of water vapour from aerial plant parts, mainly through stomata.

Plant Hormones

13. Reproduction

Human Reproduction

• Male reproductive organ – Testes.

• Female reproductive organ – Ovaries.

• Fertilisation normally occurs in the fallopian tube.

• Implantation occurs in the uterus.

• Placenta facilitates exchange between mother and foetus.

• Sperm is the male gamete.

• Ovum is the female gamete.

• Human diploid chromosome number = 46.

• Human gametes contain 23 chromosomes.

Asexual Reproduction

• Binary fission – Amoeba.

• Budding – Hydra, yeast.

• Fragmentation – Spirogyra.

• Spore formation – Rhizopus.

• Vegetative propagation – Potato, ginger, sugarcane.

14. Genetics and Evolution

• Gregor Mendel – Father of Genetics.

• Mendel performed experiments on pea plants.

• Gene – Unit of heredity.

• DNA – Deoxyribonucleic acid.

• RNA – Ribonucleic acid.

• DNA has a double-helix structure.

• Watson and Crick proposed the DNA double-helix model.

• Rosalind Franklin’s X-ray diffraction work was crucial to understanding DNA structure.

• Mutation – Change in genetic material.

• Natural selection – Proposed in evolutionary theory by Charles Darwin.

• Human beings belong to species Homo sapiens.

Important Blood Groups

• ABO blood group discovered by Karl Landsteiner.

• Rh factor is important in blood transfusion and pregnancy.

• Blood group inheritance is genetically controlled.

15. Ecology and Environment

• Ecology – Study of interactions between organisms and environment.

• Ecosystem – Living and non-living components interacting.

• Producers – Green plants.

• Consumers – Animals.

• Decomposers – Bacteria and fungi.

• Food chain – Transfer of energy between organisms.

• Food web – Interconnected food chains.

Important Ecological Terms

• Biodiversity – Variety of life.

• Habitat – Natural living place.

• Niche – Functional role of an organism.

• Biomagnification – Increase in concentration of certain pollutants at higher trophic levels.

• Eutrophication – Excess nutrient enrichment of water bodies.

• Greenhouse effect – Warming due to greenhouse gases.

• Global warming – Long-term rise in Earth’s average temperature.

• Ozone depletion – Reduction of stratospheric ozone.

Important Greenhouse Gases

• Carbon dioxide (CO₂).

• Methane (CH₄).

• Nitrous oxide (N₂O).

• Water vapour.

• Ozone.

• Fluorinated gases.

Important Environmental Facts

• Chipko Movement – Forest conservation movement.

• Silent Valley Movement – Forest conservation in Kerala.

• Project Tiger – Launched in 1973.

• Project Elephant – Launched in 1992.

• Wildlife Protection Act – 1972.

• Environment Protection Act – 1986.

• Forest Conservation Act – 1980 (now amended and titled Van (Sanrakshan Evam Samvardhan) Adhiniyam).

• Biological Diversity Act – 2002.

PART 4: MOST IMPORTANT SCIENTIFIC DISCOVERIES

PART 5: 50 MOST IMPORTANT GENERAL SCIENCE ONE-LINERS

These are useful for rapid objective-question revision.

1. SI unit of force – Newton.

2. SI unit of energy – Joule.

3. SI unit of power – Watt.

4. SI unit of pressure – Pascal.

5. Speed of light – 3 × 10⁸ m/s.

6. Speed of sound in air – Approximately 343 m/s at 20°C.

7. Human hearing range – 20 Hz to 20 kHz.

8. Device used to measure atmospheric pressure – Barometer.

9. Rear-view mirror – Convex mirror.

10. Optical fibre works on – Total internal reflection.

11. SONAR uses – Ultrasonic waves.

12. Earth gravity – Approximately 9.8 m/s².

13. Weight on Moon – One-sixth of Earth weight.

14. Commercial unit of electricity – kWh.

15. Fuse wire has – Low melting point.

16. Lightest element – Hydrogen.

17. Atomic number of carbon – 6.

18. Atomic number of oxygen – 8.

19. Atomic number of sodium – 11.

20. Atomic number of iron – 26.

21. Formula of common salt – NaCl.

22. Formula of baking soda – NaHCO₃.

23. Formula of washing soda – Na₂CO₃·10H₂O.

24. Formula of quick lime – CaO.

25. Formula of slaked lime – Ca(OH)₂.

26. Laughing gas – N₂O.

27. Dry ice – Solid CO₂.

28. Greenhouse gas – CO₂.

29. Most abundant gas in atmosphere – Nitrogen.

30. Liquid metal at room temperature – Mercury.

31. Liquid non-metal at room temperature – Bromine.

32. Hardest naturally occurring mineral – Diamond.

33. Graphite conducts electricity due to – Delocalised electrons.

34. Father of Genetics – Gregor Mendel.

35. Powerhouse of cell – Mitochondria.

36. Protein factory of cell – Ribosomes.

37. Functional unit of kidney – Nephron.

38. Functional unit of nervous system – Neuron.

39. Functional unit of heredity – Gene.

40. Largest gland in human body – Liver.

41. Largest organ of human body – Skin.

42. Longest bone – Femur.

43. Smallest bone – Stapes.

44. Largest artery – Aorta.

45. Universal RBC donor – O negative.

46. Universal RBC recipient – AB positive.

47. Vitamin C deficiency – Scurvy.

48. Vitamin D deficiency in children – Rickets.

49. Malaria is caused by – Plasmodium.

50. Photosynthesis occurs in – Chloroplasts.

PART 6: IMPORTANT FORMULAS FOR QUICK REVISION