TN 10th Science Unit-Wise Important Questions & 2-Mark / 5-Mark Solved PDF

Mastering the Tamil Nadu Class 10 (SSLC) Science syllabus requires focused preparation on high-weightage chapters, recurring conceptual questions, and structured problem-solving across Physics, Chemistry, and Biology. To build a solid academic foundation across all five board examination subjects, students should practice systematically with curated resources for Tamil (பொதுத்தமிழ்), English, Mathematics (கணிதம்), Science (அறிவியல்), and Social Science (சமூக அறிவியல்), all available on our comprehensive 10th SSLC Study Materials Hub.

In the official board examination, Science carries 100 total marks (75 marks in the written theory paper and 25 marks in school practical evaluations). Students must secure at least 20 marks in theory and 15 marks in practicals to pass, but securing a centum requires precision in 2-mark definitions, 4-mark scientific explanations, and 7-mark comprehensive essays. Students can revise foundational chapters using our Samacheer Kalvi 10th Standard Textbooks, check scheduled dates on the TN 10th Public Exam Time Table 2027, test problem speed with 10th SSLC Question Papers Archive and 10th PTA Question Bank (6 Sets), and prepare for mid-year benchmarks with 10th Half Yearly Question Papers. This guide compiles the unit-wise important 2-mark, 4-mark, and 7-mark solved questions for Tamil Medium and English Medium students.

தமிழ்நாடு 10-ஆம் வகுப்பு அறிவியல் (SSLC Science) பாடம் — இயற்பியல், வேதியியல், உயிரியல் பாடப்பிரிவுகளுக்கான அலகு வாரியான முக்கியமான 2 மதிப்பெண், 4 மதிப்பெண் மற்றும் 7 மதிப்பெண் வினா-விடைகள் PDF தொகுப்பு கீழே கொடுக்கப்பட்டுள்ளது.

Overview

TN 10th Science Question Paper Pattern & Marks Weightage

The Tamil Nadu SSLC Science question paper (75 theory marks) is structured into four distinct sections designed to assess memory recall, scientific application, conceptual analysis, and detailed diagrammatic explanations:

To score full marks in Part II and Part III, students must be thoroughly prepared for the compulsory numerical questions (Q.No. 22 and Q.No. 32), which typically test optics, electric circuits, or chemical stoichiometry calculations.

Unit-Wise Important Questions: Physics (Units 1 to 6)

Physics carries approximately 25 to 28 marks in the SSLC theory paper. The core areas of focus include Newton’s laws of motion, optical ray diagrams, thermodynamic laws, Ohm’s law circuits, and nuclear reactions.

Key 2-Mark High-Frequency Questions (Physics)

• State Newton’s Second Law of Motion: The force acting on an object is directly proportional to the rate of change of linear momentum and takes place in the direction of the force (Formula: F = m × a).
• Define Inertia and name its types: The inherent property of a body to resist any change in its state of rest or state of uniform motion unless acted upon by an external unbalanced force. Types: Inertia of rest, Inertia of motion, and Inertia of direction.
• State Snell’s Law (Second Law of Refraction): The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media: sin(i) / sin(r) = μ₂ / μ₁.
• Differentiate Convex Lens and Concave Lens: Convex lenses are thicker at the center than at the edges (converging), whereas concave lenses are thinner at the center than at the edges (diverging).
• State Joule’s Law of Heating: The heat produced in a resistor is directly proportional to the square of current (I²), the resistance (R), and the time of flow (t): H = I²Rt.
• Define Sound Echo and state the minimum distance: The repetition of the sound caused by reflection of sound waves from a distant surface. The minimum distance required to hear a distinct echo in air at 20°C is 17.2 meters.
• What are Alpha, Beta, and Gamma rays? Alpha rays are positively charged helium nuclei (₂He⁴), Beta rays are negatively charged high-speed electrons (_-1e⁰), and Gamma rays are neutral electromagnetic radiations of high frequency.

Key 4-Mark and 7-Mark High-Yield Questions (Physics)

• Derive the formula for Force using Newton’s Second Law: Step-by-step mathematical derivation showing initial momentum p₁ = mu, final momentum p₂ = mv, change in momentum Δp = m(v – u), rate of change of momentum = m(v – u)/t = ma, yielding F = kma (where k = 1, hence F = ma).
• Working principle and construction of an Electric Motor (DC Motor): Clarifies Fleming’s Left Hand Rule, rectangular coil in a magnetic field, split-ring commutator action, and conversion of electrical energy into mechanical energy.
• Human Eye defects and their corrections: Myopia (short-sightedness corrected using concave lenses) and Hypermetropia (long-sightedness corrected using convex lenses) with labelled ray diagrams.
• Nuclear Fission vs Nuclear Fusion: Comparison table covering splitting of heavy nuclei vs combination of light nuclei, critical temperatures, energy release per unit mass, and disposal of radioactive waste.

Unit-Wise Important Questions: Chemistry (Units 7 to 11)

Chemistry contributes approximately 22 to 25 marks. Key themes include the modern periodic table, solubility dynamics, reaction classifications, carbon allotropes, and ethanol-ethanoic acid conversions.

Key 2-Mark High-Frequency Questions (Chemistry)

• State Modern Periodic Law: The physical and chemical properties of elements are the periodic functions of their atomic numbers.
• Define Relative Molecular Mass (RMM): The ratio between the mass of one molecule of the substance to 1/12th of the mass of an atom of Carbon-12 (¹²C).
• Define Avogadro’s Number and state its value: The number of atoms or molecules present in one mole of any substance is constant, equal to 6.023 × 10²³.
• What is an Alloy? Give an example: A homogeneous mixture of two or more metals or one or more metals with certain non-metallic elements. Example: Brass (Copper + Zinc), Stainless Steel (Iron + Carbon + Nickel + Chromium).
• What are the necessary conditions for Rusting of Iron? The simultaneous presence of Oxygen (air) and Moisture (water). Formula of rust: Fe₂O₃ • xH₂O.
• Differentiate Exothermic and Endothermic Reactions: Exothermic reactions release heat into the surroundings (e.g., combustion of fuels), while endothermic reactions absorb heat from the surroundings (e.g., photosynthesis, thermal decomposition).
• What is a Homologous Series? A series of organic compounds having the same general molecular formula, same functional group, similar chemical properties, and differing from successive members by a −CH₂− unit.

Key 4-Mark and 7-Mark High-Yield Questions (Chemistry)

• Explain the manufacture of Ethanol from Molasses: Fermentation process involving dilution, addition of ammonium sulphate, yeast addition, invertase and zymase enzymatic conversions, and fractional distillation to produce 95.5% rectified spirit.
• Chemical differences between Saturated and Unsaturated Hydrocarbons: Structural differences (single bonds vs double/triple bonds), substitution vs addition reactions, and bromine water decolourisation test.
• Factors affecting Solubility of a Solute: Detailed explanation of the nature of solute and solvent (“like dissolves like”), temperature effects (endothermic vs exothermic dissolution), and pressure influence (Henry’s law for gases).
• Classification of Chemical Reactions based on Direction and Nature of Reactants: Reversible vs irreversible reactions, combination, decomposition, displacement, and double displacement reactions with balanced chemical equations.

Unit-Wise Important Questions: Biology (Units 12 to 23)

Biology represents the largest section, offering 28 to 30 marks. Scoring requires clear anatomical diagrams, precise terminology, and complete physiological workflows.

Key 2-Mark High-Frequency Questions (Biology)

• Differentiate Aerobic and Anaerobic Respiration: Aerobic respiration requires molecular oxygen and releases 38 ATP molecules per glucose molecule, whereas anaerobic respiration occurs in the absence of oxygen and produces lactic acid or ethanol with only 2 ATP molecules.
• Define Transpiration and state its significance: The loss of water in the form of water vapour from the aerial parts of the plant through stomata. It creates a suction pull (transpiration pull) for water transport and cools the plant surface.
• What is a Reflex Arc? The pathway taken by nerve impulses in a reflex action, consisting of a receptor organ, sensory neuron, interneuron (spinal cord), motor neuron, and effector organ.
• Name the “Master Gland” and why is it called so? The Pituitary Gland, because it produces trophic hormones (such as TSH, ACTH, FSH, and LH) that regulate and stimulate the secretion of all other endocrine glands.
• State Mendel’s Law of Segregation (Purity of Gametes): Alleles of a gene separate during gamete formation so that each gamete carries only one allele for each gene.
• What is Okazaki Fragment? Short sequences of newly synthesized DNA fragments formed on the lagging strand during DNA replication, subsequently joined by DNA ligase.
• What is the difference between Biodegradable and Non-biodegradable Waste? Biodegradable waste can be decomposed by natural biological organisms (e.g., vegetable peels, paper), while non-biodegradable waste cannot be broken down by biological agents (e.g., plastics, glass, electronic waste).

Key 4-Mark and 7-Mark High-Yield Questions (Biology)

• Internal Structure of Dicot Root vs Monocot Root: Comparative anatomical table illustrating epiblema, cortex, endodermis (Casparian strips), pericycle, vascular bundles (radial, exarch), and pith (absent/small in dicot, large in monocot).
• Structure of the Human Heart and Double Circulation: Labelled schematic diagram explaining right and left atria, right and left ventricles, pulmonary and systemic circuits, and the role of valves in preventing backflow.
• Structure and Functions of a Neuron (Nerve Cell): Structural breakdown of cyton (cell body), dendrites, axon, myelin sheath, Nodes of Ranvier, and synaptic terminals with action potential transmission.
• Structure of DNA (Watson and Crick Model): Double helix structure, polynucleotide chains, nitrogenous base pairing (Adenine = Thymine with 2 hydrogen bonds; Guanine ≡ Cytosine with 3 hydrogen bonds), sugar-phosphate backbone, and dimensional dimensions (diameter: 20 Å, helical turn: 34 Å).
• Plant Hormones and their Physiological Effects: Comprehensive summary of Auxins (apical dominance), Gibberellins (bolting and stem elongation), Cytokinins (cell division), Abscisic Acid (stress hormone and stomatal closure), and Ethylene (fruit ripening).

Compulsory Numerical Problems & Core Formulas

To guarantee full marks in the compulsory sections (Q.22 and Q.32), students must memorize the standard formulas and practice numerical problems from textbook examples:

Exam Tip: Always write the formula first, substitute values with correct SI units, and underline the final answer with units (e.g., Ω, N, J, or m/s) to ensure zero mark deductions.

Download 10th Science Important Questions & Solved PDFs

Free downloadable PDF files prepared by Tamil Nadu state subject experts and verified PTA master trainers are available below for both Tamil Medium and English Medium students:

Frequently asked questions

Which chapters in 10th Science have the highest mark weightage?

In Physics, Unit 1 (Laws of Motion), Unit 2 (Optics), and Unit 4 (Electricity) carry the highest weightage. In Chemistry, Unit 7 (Atoms and Molecules) and Unit 11 (Carbon and its Compounds) are vital. In Biology, Unit 12 (Plant Anatomy), Unit 14 (Transportation & Circulation), Unit 16 (Hormones), and Unit 18 (Heredity) carry maximum marks.

What are the compulsory questions in the SSLC Science exam?

Question No. 22 in Part II (2 marks) and Question No. 32 in Part III (4 marks) are compulsory. They are almost invariably numerical problems or applied conceptual reasoning questions selected from Physics or Chemistry.

What is the minimum mark required to pass the Class 10 Science exam?

Out of 100 total marks, students must secure at least 35 marks overall. Specifically, students must obtain a minimum of 20 marks out of 75 in the theory paper and at least 15 marks out of 25 in the school practical assessment.

Where can students download 10th Science model question papers with answer keys?

Students can download official PTA 6-set model papers, district CEO revision sets, and previous years’ public exam question papers with verified teacher answer keys directly from KalviMani’s dedicated Science study hub.

How can students secure a centum (75/75 in theory) in 10th Science?

To secure a centum, students must thoroughly cover all textbook back 1-mark questions, master numerical formula derivations for compulsory questions, draw clear labelled diagrams for 4-mark and 7-mark biology questions, and ensure proper SI units for all physics solutions.

Related pages on KalviMani

10th Science Study Materials Hub · 10th SSLC Study Materials Portal · Samacheer Kalvi 10th Textbooks PDF · TN 10th Public Exam Time Table 2027 · 10th PTA Question Bank (6 Sets) · SSLC Question Papers Archive