Tamil Nadu Class 9 Science Question Bank — Samacheer Kalvi

Physics — Measurement

1 Mark

1. What is the SI unit of length? (Metre) 2. What is a screw gauge used to measure? (Diameter of thin wires / small lengths) 3. Define least count. (Smallest measurement an instrument can reliably measure) 4. What is the SI unit of time? (Second) 5. What does a vernier calliper measure? (Lengths, inner/outer diameters)

3 Marks

1. Define least count and calculate the least count of a vernier calliper with 10 VSD = 9 MSD. 2. What are the rules for counting significant figures? Give two examples. 3. Distinguish between systematic error and random error.

5 Marks

1. Describe the construction and working of a screw gauge. How is zero error corrected? 2. What is the difference between accuracy and precision? Explain with examples.

Physics — Motion

1 Mark

1. State the first equation of motion. (v = u + at) 2. What does the slope of a velocity–time graph represent? (Acceleration) 3. What is uniform circular motion? (Constant speed along a circular path) 4. Give the SI unit of acceleration. (m/s²) 5. Is speed a scalar or vector? (Scalar)

3 Marks

1. Derive the second equation of motion (s = ut + ½at²). 2. Distinguish between distance and displacement with examples. 3. An object starts from rest and reaches 30 m/s in 10 s. Find acceleration and distance.

5 Marks

1. Derive all three equations of motion using velocity–time graph. 2. A train starts from rest with acceleration 2 m/s². Find: (a) velocity after 5s, (b) distance in 5s, (c) velocity after 100 m.

Physics — Fluids

1 Mark

1. State Pascal's law. (Pressure applied at a point in an enclosed fluid is transmitted equally in all directions) 2. What is the SI unit of pressure? (Pascal — Pa) 3. Define buoyancy. (Upward force exerted by a fluid on a submerged object) 4. Who discovered the law of flotation? (Archimedes) 5. What is atmospheric pressure at sea level? (101,325 Pa ≈ 1.01 × 10⁵ Pa)

3 Marks

1. State and explain Archimedes' Principle. 2. What is the condition for an object to float on water? 3. A block of wood has density 600 kg/m³. Will it float in water? Explain.

5 Marks

1. Explain Pascal's law with a hydraulic press example. 2. Describe the applications of Archimedes' Principle in daily life.

Chemistry — Matter and Its Surroundings

1 Mark

1. What are the three states of matter? (Solid, liquid, gas) 2. Define evaporation. (Surface phenomenon where liquid converts to vapour) 3. What is sublimation? Give an example. (Solid directly to gas — e.g., camphor, dry ice) 4. What is latent heat? (Heat absorbed/released during change of state) 5. What type of mixture is air? (Homogeneous)

3 Marks

1. Distinguish between evaporation and boiling. 2. What factors affect the rate of evaporation? 3. Explain the concept of latent heat of fusion and vaporisation.

5 Marks

1. Describe the properties of the three states of matter and explain interconversion between them.

Chemistry — Atomic Structure

1 Mark

1. Who proposed the nuclear model of the atom? (Ernest Rutherford) 2. What is the charge of a proton? (+1) 3. What is the mass number of an atom? (Protons + Neutrons) 4. What are isotopes? (Atoms with same atomic number but different mass numbers) 5. Who discovered the electron? (J.J. Thomson)

3 Marks

1. Describe Rutherford's gold foil experiment and its observations. 2. What are the limitations of Rutherford's atomic model? 3. Distinguish between isotopes and isobars with examples.

5 Marks

1. Explain the evolution of atomic models from Thomson to Bohr. 2. Describe the structure of an atom — protons, neutrons, electrons, shells.

Biology — Nutrition and Health

1 Mark

1. What is photosynthesis? (Process by which plants make food using sunlight, water, CO₂) 2. Name the green pigment in leaves. (Chlorophyll) 3. What is a balanced diet? (Diet containing all nutrients in correct proportions) 4. What disease is caused by Vitamin C deficiency? (Scurvy) 5. What is the caloric value of carbohydrates? (4 kcal/g)

3 Marks

1. Explain the process of photosynthesis with a word equation. 2. What are the functions of Vitamins A, B, C, and D? 3. What is the difference between macronutrients and micronutrients?

5 Marks

1. Describe the nutrition process in humans — from ingestion to absorption. 2. What is malnutrition? Describe any two nutritional deficiency diseases.

Biology — Nervous System

1 Mark

1. What is a neuron? (Basic structural unit of the nervous system) 2. Name the two main divisions of the nervous system. (CNS and PNS) 3. What is a reflex action? (Automatic response to a stimulus without conscious control) 4. Where is the cerebrum located? (Cerebrum is the largest part of the brain — forebrain) 5. What is a synapse? (Gap between two neurons where signals pass)

3 Marks

1. Distinguish between CNS and PNS. 2. Explain the reflex arc with a diagram. 3. What are the functions of the three parts of the brain: cerebrum, cerebellum, medulla?

5 Marks

1. Describe the structure and function of a neuron with a labelled diagram. 2. Explain how a nerve impulse is transmitted from one neuron to another.