Science Questions for SSC CGL

Physics — Key Laws and Concepts

SSC CGL tests Newton's laws, basic optics, sound, electricity, and magnetism at a conceptual level — no deep calculations. Focus on definitions, SI units, and real-life applications. For example, why a ball bounces back (Newton's third law), why a spoon looks bent in water (refraction), why thunder comes after lightning (speed of sound vs light).

• Newton's First Law: An object stays at rest or in motion unless acted upon by an external force (Inertia).
• Newton's Second Law: Force = Mass x Acceleration (F = ma). More mass needs more force.
• Newton's Third Law: Every action has an equal and opposite reaction.
• Speed of light: 3 x 10^8 m/s. Speed of sound in air: 340 m/s approximately.
• SI unit of force is Newton (N), of power is Watt (W), of energy is Joule (J).
• Concave mirror: converging, used in torches and shaving mirrors. Convex mirror: diverging, used in rear-view mirrors.

Chemistry — Acids, Bases, Metals and Everyday Reactions

SSC CGL loves acid-base questions, pH scale, common chemical names of household substances, and periodic table basics. Remember: pH below 7 is acidic, above 7 is basic, exactly 7 is neutral. Common salts and their chemical names appear frequently — baking soda, washing soda, bleaching powder are perennial favourites.

• Baking Soda: Sodium Bicarbonate (NaHCO3). Used in cooking and fire extinguishers.
• Washing Soda: Sodium Carbonate (Na2CO3). Used in cleaning.
• Bleaching Powder: Calcium Hypochlorite Ca(OCl)2. Used in disinfecting water.
• Vinegar contains Acetic Acid. Lemon juice contains Citric Acid. Stomach produces Hydrochloric Acid (HCl).
• Rust is Iron Oxide (Fe2O3). Rusting is an oxidation reaction requiring water and oxygen.
• Noble gases (He, Ne, Ar, Kr, Xe, Rn) are inert — they do not react easily. Mnemonic: He Never Argues, Keep Xenon Resting.

Biology — Human Body Systems

This is the highest-scoring science sub-topic in SSC CGL. Questions focus on organ functions, diseases and their causes, vitamins and deficiencies, and blood. Know which organ does what, which gland secretes which hormone, and which vitamin deficiency causes which disease. These facts repeat across years.

• Largest organ of the body: Skin. Largest internal organ: Liver. Smallest bone: Stapes (in ear).
• Insulin is produced by the Pancreas (Beta cells of Islets of Langerhans). Deficiency causes Diabetes.
• RBC (Red Blood Cells) carry oxygen using Haemoglobin. No nucleus in mature RBC. Lifespan: 120 days.
• WBC (White Blood Cells) fight infection. Platelets help in clotting.
• Vitamin A deficiency: Night Blindness. B1: Beriberi. C: Scurvy. D: Rickets. Mnemonic: A-Night, B1-Beri, C-Scurvy, D-Rickets.
• Malaria is caused by Plasmodium parasite, transmitted by female Anopheles mosquito. Dengue by Aedes mosquito.

Biology — Plants and Microorganisms

Photosynthesis, plant parts, microorganism diseases, and vaccines are tested. SSC sometimes asks which disease is caused by which type of microorganism — bacteria, virus, fungus, or protozoa. Know the key examples of each.

• Photosynthesis: 6CO2 + 6H2O + Light -> C6H12O6 + 6O2. Chlorophyll captures sunlight.
• Bacteria cause: TB (Tuberculosis), Cholera, Typhoid, Pneumonia.
• Virus cause: Influenza, Rabies, Polio, HIV/AIDS, COVID-19, Dengue, Hepatitis B.
• Fungus cause: Ringworm, Athlete's Foot.
• Protozoa cause: Malaria, Amoebic Dysentery, Kala-azar.
• Penicillin antibiotic was discovered by Alexander Fleming from the mould Penicillium.

Important Scientific Instruments and Inventions

SSC CGL directly asks which instrument measures what, or who invented what. These are pure memory-based questions and can be solved in under 10 seconds if you have the facts.

• Barometer: measures atmospheric pressure. Thermometer: measures temperature. Seismograph: measures earthquake intensity.
• Sphygmomanometer: measures blood pressure. Stethoscope: hears heartbeat.
• ECG (Electrocardiogram): records heart electrical activity. EEG: records brain electrical activity.
• Telephone: Alexander Graham Bell. Radioactivity: Marie Curie. Gravity (law): Isaac Newton. Evolution: Charles Darwin.
• X-ray: Wilhelm Roentgen. Penicillin: Alexander Fleming. Vaccination: Edward Jenner.

• Confusing Baking Soda (NaHCO3) with Washing Soda (Na2CO3) — remember Baking has bi (bi = bicarbonate).
• Mixing up which mosquito carries which disease — Anopheles for Malaria, Aedes for Dengue and Zika. Trick: Anopheles-Malaria both have the letter A prominently.
• Stating that the largest organ is Liver — it is actually Skin. Liver is the largest internal organ. SSC plays on this exact distinction.
• Confusing Concave and Convex mirrors — remember Concave is Cave-shaped (hollow inward), used to focus light. Convex bulges outward, gives wider view for rear mirrors.
• Forgetting that Vitamin D is made by skin in sunlight — deficiency causes Rickets in children, Osteomalacia in adults. Many aspirants only remember Rickets and miss the adult form.

• Vitamin deficiency chain: A-Night B-Beri C-Scurvy D-Rickets K-Klotting (K helps blood clotting). First letters: AN BB CS DR KK.
• Noble gases order: He Never Argued; Keep Xenon Rested — Helium, Neon, Argon, Krypton, Xenon, Radon.
• Mosquito-disease: AEDES = Aedes Eats Dengue Every Season. ANOPHELES = Anopheles Needs Malaria (both start with AN).
• For mirrors: C for Concave = Collects light (converging). V for conVex = Very wide view (diverging).

• SSC CGL Tier 1 GK section has roughly 25 questions total — expect 5-7 from science. Of these, 2 are almost always from Biology (vitamins or diseases), 1-2 from Chemistry (chemical names or pH), and 1-2 from Physics (units or laws).
• Questions are statement-based, not calculation-heavy. You will rarely solve an equation — you identify the correct fact. Speed matters more than depth here.
• Recent CGL papers (2022-2024) have increased focus on health and disease, nutrition, and environment-related science. Vitamins, deficiency diseases, and organ functions are near-certain topics.
• Chemical names of everyday substances (baking soda, plaster of Paris, laughing gas, dry ice) have appeared in almost every CGL paper for the last 5 years. Plaster of Paris is CaSO4.0.5H2O and laughing gas is Nitrous Oxide (N2O).
• Do not skip Physics units — SI units of common quantities (force, pressure, power, frequency) are asked directly and take only 10 seconds to answer if memorized. Frequency unit is Hertz, Pressure is Pascal, Power is Watt.