TNPSC Group II · Bite-size lessons
General Science
About 6 min · General Studies · English
Time worked out from the lesson's 383 words at 150 words a minute, plus a minute for each question.
The syllabus emphasizes scientific knowledge, scientific temper, and applications — meaning you must understand basic principles and their real-world relevance, not just memorize isolated facts.
Key ideas
- Scientific Method: Observation → Hypothesis → Experimentation → Analysis → Conclusion. Science progresses through evidence-based, repeatable inquiry — not belief or authority.
- SI Units: Seven base units — metre (length), kilogram (mass), second (time), ampere (current), kelvin (temperature), mole (amount), candela (luminous intensity). All scientific measurements derive from these.
- Laws of Motion (Newton): First law — inertia; Second law — F = ma (force equals mass times acceleration); Third law — every action has an equal and opposite reaction.
- Energy Conservation: Energy cannot be created or destroyed, only transformed. Example: electrical energy → light + heat in a bulb.
- Atomic Structure: Atom = nucleus (protons + neutrons) + electrons in shells. Atomic number = number of protons; Mass number = protons + neutrons.
Watch out for
- Confusing speed with velocity: Speed is scalar (only magnitude); velocity is vector (magnitude + direction). "60 km/h north" is velocity, not just speed.
- Mixing atomic number and mass number: Atomic number = protons only (defines element); mass number = protons + neutrons. Carbon-12 has 6 protons, 6 neutrons.
- Assuming all acids are dangerous: Many acids are essential — HCl in stomach aids digestion; citric acid in fruits is harmless. Concentration and type matter.
Quick reference
- Scientific temper = questioning attitude + evidence-based thinking + rejecting superstition.
- Gravity on Earth ≈ 9.8 m/s² (often rounded to 10 m/s² in calculations).
- Density of water = 1 g/cm³ or 1000 kg/m³ — reference for floating/sinking.
- Vitamin deficiency diseases: A = Night blindness; B₁ = Beriberi; C = Scurvy; D = Rickets.
- Communicable vs Non-communicable: Communicable = spread person-to-person (TB, COVID); Non-communicable = lifestyle/genetic (diabetes, cancer).
Check yourself: 3 questions
1. Which of the following pairs of gases are mainly responsible for the greenhouse effect leading to global warming?
2. A person with blood group AB can receive blood from which of the following blood groups?
3. In the context of plant nutrition, which of the following elements is a constituent of chlorophyll and is essential for photosynthesis?
This lesson is cut from the topic's note, not rewritten. Fact-checked on 17 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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