1. Introduction to General Science
General Science is an essential component of competitive examinations in India, testing candidates' understanding of basic scientific concepts from Physics, Chemistry, and Biology. Unlike specialized science exams, General Science in competitive tests focuses on fundamental principles that are relevant to everyday life and general awareness.
The subject covers a wide range of topics from mechanics and electricity in Physics, to chemical reactions and elements in Chemistry, to human body systems and diseases in Biology. Additionally, questions on Environment and Ecology, and Science and Technology (including recent developments) are increasingly common.
For UPSC, SSC, Railway, Banking, and State PSC examinations, General Science questions are typically straightforward, testing conceptual understanding rather than mathematical problem-solving. This guide provides a comprehensive overview of all major topics, focusing on frequently asked concepts and facts.
Subject Weightage in Various Exams:
- UPSC Prelims: 8-12 questions (including Environment and Science & Technology)
- SSC CGL/CHSL: 5-8 questions in General Awareness section
- Railway NTPC: 10-15 questions (significant weightage)
- State PSC: Varies by state, usually 10-15 questions
- Defence Exams: 15-20 questions
2. Physics - Fundamental Concepts
2.1 Mechanics and Motion
- Newton's Laws of Motion:
- First Law (Law of Inertia): A body at rest stays at rest, a body in motion stays in motion unless acted upon by external force.
- Second Law: Force = Mass x Acceleration (F = ma)
- Third Law: Every action has an equal and opposite reaction
- Gravitation: Newton's Law of Universal Gravitation states every particle attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them. Acceleration due to gravity (g) = 9.8 m/s².
- Work, Energy, Power: Work = Force x Displacement. Energy is the capacity to do work. Power = Work/Time. SI units: Joule, Joule, Watt respectively.
- Simple Machines: Lever, pulley, wheel and axle, inclined plane, screw, wedge. Mechanical Advantage = Load/Effort.
2.2 Heat and Thermodynamics
- Temperature Scales: Celsius (°C), Fahrenheit (°F), Kelvin (K). C/5 = (F-32)/9 = (K-273)/5
- Modes of Heat Transfer: Conduction (through solids), Convection (through fluids), Radiation (through vacuum)
- Specific Heat: Heat required to raise temperature of 1 kg by 1°C. Water has highest specific heat (4.2 J/g°C).
- Laws of Thermodynamics: First Law (Energy Conservation), Second Law (Entropy), Third Law (Absolute Zero)
Important Physical Constants:
- Speed of Light: 3 x 10⁸ m/s
- Speed of Sound (air, 20°C): 343 m/s
- Acceleration due to Gravity: 9.8 m/s²
- Absolute Zero: -273.15°C or 0 Kelvin
- Atmospheric Pressure: 1.013 x 10⁵ Pascal
2.3 Light and Optics
- Reflection: Bouncing of light from a surface. Laws: angle of incidence = angle of reflection.
- Refraction: Bending of light when passing from one medium to another. Causes mirages, apparent depth.
- Dispersion: Splitting of white light into seven colors (VIBGYOR) - as in rainbow.
- Human Eye: Cornea, iris, pupil, lens, retina (rods and cones). Eye defects: Myopia (short-sightedness), Hypermetropia (long-sightedness), Astigmatism, Presbyopia.
- Mirrors: Plane, Concave (converging), Convex (diverging). Used in periscopes, telescopes, vehicle mirrors.
- Lenses: Convex (converging) - magnifying glass; Concave (diverging) - correcting myopia.
2.4 Sound
- Nature: Sound is a mechanical wave requiring medium. Cannot travel in vacuum.
- Characteristics: Pitch (frequency), Loudness (amplitude), Quality (timbre)
- Audible Range: 20 Hz to 20,000 Hz for humans
- Ultrasound: Above 20,000 Hz. Used in SONAR, medical imaging, cleaning.
- Echo: Reflection of sound. Minimum distance needed: 17.2 meters (at 20°C)
2.5 Electricity and Magnetism
- Electric Current: Flow of electrons. Measured in Amperes (A). I = Q/t
- Ohm's Law: V = IR (Voltage = Current x Resistance)
- Resistance: Opposition to current flow. Measured in Ohms (Ω). Conductors have low resistance, insulators have high.
- Electric Power: P = VI = I²R = V²/R. Measured in Watts.
- Magnetism: Magnetic field around current-carrying conductor. Electromagnets, motors, generators.
- Electromagnetic Induction: Discovered by Faraday. Basis of generators and transformers.
3. Chemistry - Essential Topics
3.1 Matter and Atomic Structure
- States of Matter: Solid (fixed shape and volume), Liquid (fixed volume, takes shape of container), Gas (neither fixed shape nor volume), Plasma (ionized gas)
- Atomic Structure: Nucleus (protons + neutrons) surrounded by electrons. Protons are positive, electrons negative, neutrons neutral.
- Atomic Number: Number of protons. Mass Number: Protons + Neutrons
- Isotopes: Same atomic number, different mass numbers (e.g., C-12, C-14)
- Isobars: Same mass number, different atomic numbers
3.2 Periodic Table
The Modern Periodic Table was developed by Dmitri Mendeleev and later modified by Henry Moseley (based on atomic number). It has 18 groups and 7 periods. Elements are arranged in order of increasing atomic number.
Important Element Groups:
- Group 1 (Alkali Metals): Li, Na, K, Rb, Cs, Fr - highly reactive, stored in kerosene
- Group 2 (Alkaline Earth): Be, Mg, Ca, Sr, Ba, Ra
- Group 17 (Halogens): F, Cl, Br, I, At - highly reactive non-metals
- Group 18 (Noble Gases): He, Ne, Ar, Kr, Xe, Rn - inert, stable
- Transition Metals: Groups 3-12, includes Fe, Cu, Ag, Au, Pt
3.3 Chemical Reactions and Equations
- Types of Reactions:
- Combination: A + B → AB
- Decomposition: AB → A + B
- Single Displacement: A + BC → AC + B
- Double Displacement: AB + CD → AD + CB
- Combustion: Reaction with oxygen, releases heat
- Redox: Oxidation-Reduction (electron transfer)
- Catalysts: Substances that speed up reactions without being consumed. Enzymes are biological catalysts.
3.4 Acids, Bases, and Salts
- Acids: Release H+ ions in water. Turn blue litmus red. Examples: HCl, H₂SO₄, HNO₃, acetic acid (vinegar)
- Bases: Release OH- ions. Turn red litmus blue. Examples: NaOH, KOH, Ca(OH)₂
- pH Scale: Measures acidity/basicity. 0-14 scale. 7 is neutral. Below 7 is acidic, above 7 is basic.
- Salts: Formed by acid-base neutralization. NaCl (common salt), baking soda (NaHCO₃), washing soda (Na₂CO₃)
3.5 Important Compounds and Their Uses
- Water (H₂O): Universal solvent, essential for life
- Carbon Dioxide (CO₂): Greenhouse gas, used in fire extinguishers, fizzy drinks
- Ozone (O₃): Protects from UV radiation in stratosphere
- Ammonia (NH₃): Fertilizers, cleaning agents
- Sulfuric Acid (H₂SO₄): King of chemicals, used in batteries, fertilizers
- Chlorine (Cl₂): Water purification, bleaching
- Hydrogen Peroxide (H₂O₂): Disinfectant, bleaching agent
3.6 Metals and Non-Metals
- Metals: Good conductors, malleable, ductile, lustrous, solid at room temperature (except mercury)
- Non-Metals: Poor conductors (except graphite), brittle. Carbon, sulfur, phosphorus.
- Alloys: Mixtures of metals. Steel (Fe+C), Brass (Cu+Zn), Bronze (Cu+Sn), Stainless Steel (Fe+Cr+Ni)
- Corrosion: Rusting of iron (Fe₂O₃.xH₂O). Prevention: galvanization, painting, alloying.
4. Biology - Life Sciences
4.1 Cell Biology
- Cell: Basic structural and functional unit of life. Discovered by Robert Hooke (1665).
- Prokaryotic Cells: No nucleus (bacteria, blue-green algae)
- Eukaryotic Cells: Have nucleus (plants, animals, fungi)
- Cell Organelles: Nucleus (control center), Mitochondria (powerhouse), Ribosomes (protein synthesis), Chloroplast (photosynthesis in plants), Cell membrane, Cell wall (plants)
- DNA: Deoxyribonucleic Acid - genetic material. Double helix structure discovered by Watson and Crick.
4.2 Human Body Systems
Major Body Systems:
- Circulatory System: Heart, blood vessels, blood. Heart has 4 chambers. Blood groups: A, B, AB, O. Rh factor.
- Respiratory System: Lungs, trachea, bronchi. Exchange of O₂ and CO₂.
- Digestive System: Mouth → Esophagus → Stomach → Small intestine → Large intestine. Enzymes: amylase, pepsin, lipase.
- Nervous System: Brain, spinal cord, nerves. Neurons transmit signals.
- Excretory System: Kidneys (filter blood), urinary bladder, skin (sweat).
- Skeletal System: 206 bones in adult. Provides structure, protection.
- Endocrine System: Hormones. Pituitary (master gland), Thyroid, Pancreas, Adrenal.
4.3 Nutrition and Vitamins
Vitamins and Deficiency Diseases:
- Vitamin A (Retinol): Night blindness, Xerophthalmia. Sources: Carrots, liver, fish oil
- Vitamin B1 (Thiamine): Beriberi. Sources: Whole grains, meat
- Vitamin B12 (Cobalamin): Anemia. Sources: Meat, eggs, dairy
- Vitamin C (Ascorbic Acid): Scurvy. Sources: Citrus fruits, tomatoes
- Vitamin D (Calciferol): Rickets, Osteomalacia. Sources: Sunlight, fish, milk
- Vitamin E (Tocopherol): Reproductive disorders. Sources: Nuts, vegetable oils
- Vitamin K: Delayed blood clotting. Sources: Green vegetables
4.4 Diseases and Health
- Communicable Diseases:
- Bacterial: Tuberculosis, Typhoid, Cholera, Tetanus
- Viral: COVID-19, Influenza, Dengue, AIDS, Polio, Rabies
- Protozoan: Malaria (Plasmodium), Amoebic dysentery
- Fungal: Ringworm, Athlete's foot
- Non-communicable Diseases: Diabetes, Cancer, Heart disease, Hypertension
- Vaccines: BCG (TB), OPV (Polio), DPT (Diphtheria, Pertussis, Tetanus), MMR (Measles, Mumps, Rubella)
4.5 Plants and Photosynthesis
- Photosynthesis: 6CO₂ + 6H₂O + Light → C₆H₁₂O₆ + 6O₂. Occurs in chloroplasts using chlorophyll.
- Respiration: Opposite of photosynthesis. Glucose + O₂ → CO₂ + H₂O + Energy
- Plant Parts: Root (absorption), Stem (transport), Leaf (photosynthesis), Flower (reproduction)
- Plant Hormones: Auxins (growth), Gibberellins, Cytokinins, Ethylene (ripening)
5. Environment and Ecology
5.1 Ecosystems
- Ecosystem: Community of living organisms interacting with their environment. Biotic (living) + Abiotic (non-living) components.
- Food Chain: Producers → Primary Consumers → Secondary Consumers → Tertiary Consumers → Decomposers
- Food Web: Interconnected food chains in an ecosystem
- Types: Terrestrial (forest, grassland, desert), Aquatic (freshwater, marine)
5.2 Biodiversity and Conservation
- Biodiversity Hotspots in India: Eastern Himalayas, Western Ghats, Indo-Burma, Sundaland
- Protected Areas: National Parks (strict protection), Wildlife Sanctuaries (some human activity allowed), Biosphere Reserves (conservation + sustainable use)
- Endangered Species: Tiger, One-horned Rhino, Asiatic Lion, Snow Leopard
- Conservation Programs: Project Tiger (1973), Project Elephant, Crocodile Conservation
5.3 Environmental Issues
- Global Warming: Rise in Earth's temperature due to greenhouse gases (CO₂, CH₄, N₂O)
- Ozone Depletion: Caused by CFCs. Montreal Protocol (1987) addresses this.
- Pollution: Air (particulate matter, gases), Water (industrial effluents), Soil (pesticides, plastic)
- Climate Change: Paris Agreement (2015) - limit warming to 1.5-2°C
6. Science and Technology
6.1 Space Technology
- ISRO: Indian Space Research Organisation (1969). Headquarters: Bengaluru
- Launch Vehicles: PSLV (Polar Satellite Launch Vehicle), GSLV (Geosynchronous), LVM3
- Missions: Chandrayaan (Moon), Mangalyaan (Mars), Gaganyaan (Human spaceflight)
- Satellites: INSAT (communication), IRS (remote sensing), GSAT (communication), NavIC (navigation)
6.2 Nuclear Technology
- Nuclear Fission: Splitting of heavy nucleus (U-235). Used in nuclear reactors.
- Nuclear Fusion: Combining light nuclei (Hydrogen). Powers the sun.
- India's Nuclear Program: DAE (Department of Atomic Energy), BARC, Nuclear Power Plants at Tarapur, Kudankulam, Kalpakkam
- Radioactivity: Alpha, Beta, Gamma rays. Applications in medicine, industry.
6.3 Biotechnology
- Genetic Engineering: Modifying DNA. GM crops (Bt cotton), Gene therapy
- Cloning: Producing identical copies. Dolly the sheep (1996)
- Stem Cells: Undifferentiated cells with regenerative potential
- Applications: Pharmaceuticals, agriculture, biofuels, environmental cleanup
6.4 Information Technology
- Artificial Intelligence: Machine learning, neural networks, natural language processing
- Blockchain: Distributed ledger technology, cryptocurrencies
- Quantum Computing: Uses quantum mechanics for computation
- 5G Technology: Fifth generation mobile networks, higher speeds, lower latency
7. Important Scientific Facts
Scientific Discoveries
- Gravity: Isaac Newton
- Electricity: Benjamin Franklin
- X-rays: Wilhelm Rontgen
- Radioactivity: Henri Becquerel
- Penicillin: Alexander Fleming
- DNA Structure: Watson & Crick
- Vaccination: Edward Jenner
Scientific Instruments
- Thermometer: Temperature
- Barometer: Atmospheric pressure
- Hygrometer: Humidity
- Seismograph: Earthquakes
- Ammeter: Electric current
- Voltmeter: Voltage
- Microscope: Magnification
Scientific Units (SI)
- Length: Meter (m)
- Mass: Kilogram (kg)
- Time: Second (s)
- Temperature: Kelvin (K)
- Electric Current: Ampere (A)
- Luminous Intensity: Candela (cd)
- Amount of Substance: Mole (mol)
Indian Scientists
- C.V. Raman: Raman Effect (Nobel 1930)
- S.N. Bose: Bose-Einstein Statistics
- Homi Bhabha: Nuclear Program
- A.P.J. Abdul Kalam: Missile Program
- Vikram Sarabhai: Space Program
- Har Gobind Khorana: Nobel in Medicine
8. Sample Questions with Answers
Q1. Which vitamin deficiency causes scurvy?
- A) Vitamin A
- B) Vitamin B
- C) Vitamin C
- D) Vitamin D
Answer: C) Vitamin C
Vitamin C (Ascorbic Acid) deficiency causes scurvy, characterized by bleeding gums and skin problems. Found in citrus fruits.
Q2. The powerhouse of the cell is:
- A) Nucleus
- B) Ribosome
- C) Mitochondria
- D) Golgi Body
Answer: C) Mitochondria
Mitochondria are called the powerhouse of the cell because they produce ATP (energy) through cellular respiration.
Q3. Which gas is known as laughing gas?
- A) Carbon Dioxide
- B) Nitrous Oxide
- C) Nitrogen
- D) Oxygen
Answer: B) Nitrous Oxide (N₂O)
Nitrous Oxide is called laughing gas because inhaling it can cause euphoria and laughter. Used as anesthetic in dentistry.
Q4. The speed of sound is maximum in:
- A) Air
- B) Water
- C) Steel
- D) Vacuum
Answer: C) Steel
Sound travels fastest in solids (like steel ~5,960 m/s), slower in liquids (~1,480 m/s in water), slowest in gases (~343 m/s in air). Cannot travel in vacuum.
Q5. Which metal is liquid at room temperature?
- A) Lead
- B) Mercury
- C) Zinc
- D) Copper
Answer: B) Mercury
Mercury is the only metal that is liquid at room temperature (melting point -39°C). Used in thermometers and barometers.
Q6. Photosynthesis takes place in:
- A) Mitochondria
- B) Chloroplast
- C) Nucleus
- D) Ribosome
Answer: B) Chloroplast
Photosynthesis occurs in chloroplasts which contain chlorophyll. Plants use sunlight, CO₂, and water to produce glucose and oxygen.
Q7. The Nobel Prize in Physics 1930 was awarded to which Indian scientist?
- A) S.N. Bose
- B) C.V. Raman
- C) Homi Bhabha
- D) Vikram Sarabhai
Answer: B) C.V. Raman
C.V. Raman received the Nobel Prize in Physics in 1930 for his discovery of the Raman Effect (scattering of light).
9. Tips for Competitive Exams
- 1Focus on NCERT:
Class 6-10 Science NCERT books are sufficient for most competitive exams. Read them thoroughly.
- 2Learn Scientific Vocabulary:
Know scientific terms, units, and instruments. These are frequently asked as direct questions.
- 3Stay Updated on Science News:
ISRO missions, scientific discoveries, and health-related news are important for current affairs.
- 4Link Science with Daily Life:
Understand practical applications - why pressure cooker cooks faster, how mirrors work, etc.
- 5Focus on Diseases for Railway/SSC:
Railway and SSC exams often ask about diseases, vitamins, and human body. Make comprehensive notes.
10. Frequently Asked Questions
Q: How many Science questions come in SSC and Railway exams?
A: SSC CGL has about 5-8 science questions in General Awareness. Railway NTPC has 10-15 science questions. These are usually straightforward factual questions.
Q: Is Science difficult for arts background students?
A: No, competitive exam science is basic and conceptual, not mathematical. NCERT Class 6-10 science is sufficient. Focus on understanding rather than memorizing.
Q: Which topics are most important in General Science?
A: Human body (diseases, vitamins, organs), Physics basics (light, sound, electricity), Chemistry (elements, compounds, reactions), and Environment are most frequently asked.
Q: Should I study Science and Technology for UPSC separately?
A: Yes, UPSC asks separate Science & Technology questions covering biotechnology, space, nuclear, and IT developments. Follow Science Reporter magazine and PIB updates.