SSC GD · Bite-size lessons

General Science

About 7 min · General Knowledge and General Awareness · English

Time worked out from the lesson's 498 words at 150 words a minute, plus a minute for each question.

This topic tests fundamental concepts at the matriculation level — the kind of science you encounter in daily life and read about in newspapers. Success here doesn't require deep theoretical knowledge but demands clarity on basic principles, definitions and real-world applications.

Key ideas

• Physics is about motion, energy and forces: Understand the behaviour of objects (Newton's laws), energy transformations (potential to kinetic), properties of light (reflection, refraction) and electricity basics (current, resistance, conductors vs insulators).
• Chemistry deals with matter and its transformations: Focus on atomic structure (protons, neutrons, electrons), the periodic table layout, chemical reactions (synthesis, decomposition), and properties of common substances like acids (pH < 7, turn litmus red), bases (pH > 7, slippery feel) and salts.
• Biology covers living systems: The cell is the basic unit of life. Know major organelles (nucleus holds DNA, mitochondria produce energy, chloroplasts do photosynthesis in plants). Human body systems — digestive, respiratory, circulatory, nervous — and their main organs appear frequently.
• Nutrition and deficiency diseases: Vitamins (A, B-complex, C, D, E, K) and minerals (iron, calcium, iodine) each have specific roles and deficiency symptoms. For example, Vitamin C deficiency causes scurvy, iodine deficiency causes goitre.
• Everyday applications connect theory to life: Rusting is oxidation of iron, a mirror uses reflection, a lens in spectacles uses refraction, vaccines use weakened pathogens to build immunity, and pasteurisation kills bacteria in milk by heating.

Watch out for

• Confusing speed and velocity: Speed is scalar (magnitude only); velocity is vector (magnitude + direction). In SSC GD, "speed" usually means average speed = total distance / total time. Students often add speeds directly instead of using total distance and total time separately.
• Mixing up acids and bases on the pH scale: Remember pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic. A common error is thinking pH 8 is acidic. Also, strong acids have low pH (near 0), strong bases have high pH (near 14).
• Thinking all diseases are caused by germs: Many diseases result from nutritional deficiencies (scurvy, beriberi, anaemia) or genetic/lifestyle factors (diabetes, hypertension). Not every disease needs an antibiotic — antibiotics work only against bacteria, not viruses.

Quick reference

• Newton's laws: (1) Object stays at rest/motion unless force acts; (2) F = ma; (3) Action and reaction are equal and opposite.
• pH: Acids < 7 < Bases. Neutral = 7 (pure water).
• Photosynthesis: Plants use CO₂ + H₂O + light → glucose + O₂. Occurs in chloroplasts.
• Common deficiencies: Vit A → night blindness; Vit C → scurvy; Vit D → rickets; Iron → anaemia; Iodine → goitre.
• SI base units: m (length), kg (mass), s (time), A (current), K (temperature), mol (substance), cd (light).

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 18 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.

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