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TNPSC general science: the Unit I syllabus, key facts and common traps

By the PrepMatic team · Updated 8 Oct 2026 · 7 min read

TNPSC General Science is Unit I of the General Studies paper, at SSLC standard. In the Group 4 notification of October 2026 it carries an indicative 5 of the 75 General Studies questions, about 7.5 marks of 300, and TNPSC says such unit-wise counts are only indicative. The questions are short, factual and drawn from school-level physics, chemistry and biology, so a focused two to three weeks on the Class 6 to 10 science books, plus a one-page fact sheet per branch, is usually enough.

What the official syllabus lists

The Group 4 syllabus (code 496) words Unit I as one long sentence. Broken into study blocks:

The phrase "everyday application" is the key. Questions are rarely derivations. They ask what a device does, which law explains an event, what a substance is used for, or which deficiency causes which disease. The last block overlaps with TNPSC current affairs, which the syllabus names explicitly in this unit.

Physics: quantities, units and formulas

Most physics questions can be answered if you know the unit, the formula and one daily-life example for each quantity.

Three quick checks show the level of calculation to expect.

• Unit conversion: 72 km/h is 72 × 1000 / 3600 = 20 m/s.
• Energy: a 2 kg object raised 5 m gains potential energy mgh = 2 × 9.8 × 5 = 98 J (using g = 9.8 m/s²).
• Ohm's law: a 12 V supply across a 4 ohm resistor gives a current of 12 / 4 = 3 A.

Beyond calculations, keep facts like these on a sheet: light travels fastest in vacuum (about 3 × 10⁸ m/s); sound needs a medium and travels faster in solids than in air; a concave mirror is used in torches and shaving mirrors, a convex mirror in vehicle rear-view mirrors; the lens in the human eye is convex; and nuclear fission splits a heavy nucleus while fusion joins light nuclei.

Chemistry: compounds, metals and materials

Metallurgy questions usually test the order: ore, concentration, extraction (reduction or electrolysis), refining. Reactivity-series questions test which metals can displace others.

Biology: classification, body systems and health

Biology is the largest block in the unit and also the most question-friendly, because the answers are short facts.

• Classification: the five-kingdom scheme (Monera, Protista, Fungi, Plantae, Animalia); binomial nomenclature is credited to Linnaeus.
• Genetics and evolution: Mendel's pea-plant experiments; DNA as the genetic material; 46 chromosomes (23 pairs) in humans; Darwin's natural selection.
• Body systems: heart with four chambers; red blood cells carry oxygen via haemoglobin; the kidney's functional unit is the nephron; insulin is produced by the pancreas; the liver is the largest gland and the skin the largest organ; an adult has 206 bones, and the femur is the longest.
• Nutrition: the table below is the most reliable scorer.

Infections and their causes are the other staple.

Health and hygiene questions are common-sense statements: balanced diet, safe drinking water, immunisation, and the difference between communicable and non-communicable diseases.

Environment and technology

Environmental questions mix with the geography unit: the ozone layer sits in the stratosphere; CFCs deplete it, and the Montreal Protocol (1987) targets them; carbon dioxide and methane are greenhouse gases; sulphur and nitrogen oxides cause acid rain. For "latest inventions", track new missions, launches and breakthroughs in the period before your exam. The method is in the current affairs guide, and the climate-change side is covered in TNPSC geography.

Traps that cost marks

• Mass versus weight. Mass is in kilograms and does not change; weight is a force measured in newtons and depends on gravity.
• Similar-sounding diseases and deficiencies. Scurvy is vitamin C; rickets is vitamin D. Write the pairs, do not trust memory.
• "Which is not correct" stems. Underline the word "not" before you read the options.
• Bacteria versus virus. Typhoid and cholera are bacterial; dengue and polio are viral.
• Old textbook facts. Samacheer Kalvi books have been revised. If a fact differs from an old guide, trust the current edition and the syllabus, and check the date on any note you use.

Plan the unit, and where the questions come from

Because only 5 of 200 questions fall here, avoid spending your best study hours on it. A practical routine: read each branch once, make a single page of formulas, units and tables like the ones above, then revise it weekly and test yourself with questions. The Group 2 prelims use the same unit title at degree standard (see the Group 2 syllabus), so a Group 2 aspirant should add the Class 11 and 12 science books and expect more depth. Where to find the books is in the TNPSC books guide. The full unit split for Group 4 is on the Group 4 syllabus page.

Practising science with PrepMatic

Use the free assessment to learn whether general studies is a weak subject for you. Then use a topic test (about 15 questions, 30 minutes) after you finish each branch, or build a custom mock where you choose the subjects, number of questions, duration and difficulty. You can also upload your own notes and generate a mock from them. Practice questions are AI-generated, so use them to build speed, and settle any doubt with the textbook. The mock-test guide explains how to fit these into a weekly plan.

Frequently asked questions

How many General Science questions come in TNPSC Group 4?

Unit I, General Science, has an indicative 5 questions out of the 75 General Studies questions in the Group 4 notification. TNPSC states that the unit-wise distribution is only indicative.

What is the difficulty level of TNPSC General Science?

The Group 4 General Studies syllabus is SSLC standard, so the science is Class 10 level and below. For the Group 2 prelims, General Studies is at degree standard, so questions can be more detailed.

Which Samacheer Kalvi science books should I read?

Read the physics, chemistry and biology portions of the Class 6 to 10 science books. Many aspirants add Class 11 and 12 science for Group 2. That is a common convention; TNPSC itself does not prescribe textbooks for this unit.

Is current affairs part of the science unit?

Yes in wording. The Unit I text ends with "latest inventions in science and technology; current affairs", so recent science and technology news is fair game.

Do I need to memorise all the formulas?

Memorise the basic ones in the table above and understand the units. Questions at this level tend to ask for a unit, a definition or a simple calculation, not a long derivation.

Official sources

• Group 4 Notification No. 11/2026, Annexure III (syllabus code 496): the official Unit I wording and indicative question count.
• Group 2 and 2A Notification No. 11/2025: the prelims scheme at degree standard.
• Tamil Nadu School Education textbooks: official Samacheer Kalvi downloads.

Check the latest notification for the exact unit wording and question counts of the exam you are applying for. The TNPSC guide lists every exam and subject page.

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