9th Standard Science Midterm Exam Important Questions 2026–2027 (Tamil Nadu State Board) | PDF Download
This page covers the Important 2-Mark and 5-Mark Questions and Answers for the 9th Standard Science First Midterm Exam 2026, along with the Kalvi Mini Model Question Paper and Answer Key. These questions are prepared unit-wise as per the June and July portions to help students revise quickly before the exam.
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| 9th Standard Science Midterm Exam Important Questions 2026–2027 (Tamil Nadu State Board) | PDF Download |
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Unit 1: Measurement (June Portion)
Question No. 1: Define measurement.
Answer: Measurement is the base of all scientific studies and experimentations. It plays a vital role in our daily life. It is the process of finding a physical quantity such as length, mass, time and temperature.
Question No. 2: Define standard unit.
Answer: A unit is the fundamental quantity with which unknown quantities are compared. To have uniformity in measurements, we need a standard unit.
Question No. 3: What is the full form of SI system?
Answer: International System of Units.
Question No. 4: Define least count of any device.
Answer: The smallest length which can be measured by a device is called its least count.
Question No. 5: What do you know about pitch of screw gauge?
Answer: Pitch of the screw is the distance moved by the tip of the screw for one complete rotation of the head.
Question No. 6: Write the need of a standard unit.
Answer: To have uniformity in measurements, we need a standard unit.
Question No. 7: Differentiate mass and weight.
Answer:
Mass: 1. It is a fundamental quantity. 2. It has magnitude alone – scalar quantity. 3. It is the amount of matter contained in a body. 4. Remains the same everywhere. 5. It is measured using physical balance. 6. Its unit is kilogram.
Weight: 1. It is a derived quantity. 2. It has magnitude and direction – vector quantity. 3. It is the normal force exerted by the surface on the object against gravitational pull. 4. Varies from place to place. 5. It is measured using spring balance. 6. Its unit is newton.
Mass: 1. It is a fundamental quantity. 2. It has magnitude alone – scalar quantity. 3. It is the amount of matter contained in a body. 4. Remains the same everywhere. 5. It is measured using physical balance. 6. Its unit is kilogram.
Weight: 1. It is a derived quantity. 2. It has magnitude and direction – vector quantity. 3. It is the normal force exerted by the surface on the object against gravitational pull. 4. Varies from place to place. 5. It is measured using spring balance. 6. Its unit is newton.
Question No. 8: How will you measure the least count of Vernier caliper?
Answer: Least count (LC) = Value of one smallest main scale division / Total number of Vernier scale divisions.
Question No. 9: Write the rules that are followed in writing the symbols of units in SI system.
Answer:
(1) The units named after scientists are not written with a capital initial letter. E.g. newton, henry, ampere and watt.
(2) The symbols of the units named after scientists should be written by a capital letter. E.g. N for newton, H for henry, A for ampere and W for watt.
(3) Small letters are used as symbols for units not derived from a proper noun. E.g. m for metre, kg for kilogram.
(4) No full stop or other punctuation marks should be used within or at the end of symbols. E.g. 50 m and not 50 m.
(5) The symbols of the units are not expressed in plural form. E.g. 10 kg not as 10 kgs.
(1) The units named after scientists are not written with a capital initial letter. E.g. newton, henry, ampere and watt.
(2) The symbols of the units named after scientists should be written by a capital letter. E.g. N for newton, H for henry, A for ampere and W for watt.
(3) Small letters are used as symbols for units not derived from a proper noun. E.g. m for metre, kg for kilogram.
(4) No full stop or other punctuation marks should be used within or at the end of symbols. E.g. 50 m and not 50 m.
(5) The symbols of the units are not expressed in plural form. E.g. 10 kg not as 10 kgs.
Question No. 10: Find the mass of an object weighing 98 N.
Answer: Weight (W) = mg. Mass (m) = W/g. m = 98 / 9.8 = 10 kg.
Unit 10: Matter Around Us (June Portion)
Question No. 11: Differentiate between absorption and adsorption.
Answer:
Absorption: Process by which atoms, molecules, or ions enter a bulk phase (liquid, gas, solid).
Adsorption: Adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface.
Absorption: Process by which atoms, molecules, or ions enter a bulk phase (liquid, gas, solid).
Adsorption: Adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface.
Question No. 12: Define Sublimation.
Answer: The process by which a solid changes directly into a gas without passing through the liquid state.
Question No. 13: A few drops of 'Dettol' when added to water the mixture turns turbid. Why?
Answer: Dettol contains liquid-liquid particles which get scattered in another liquid (water) forming an emulsion.
Question No. 14: Write the differences between elements and compounds and give an example for each.
Answer:
Elements: Made up of only one kind of atoms. Cannot be broken down into simpler substances. Example: Iron, Copper.
Compounds: Made up of more than one kind of atoms combined chemically. Can be broken down into elements by chemical reactions. Example: Water (H2O), Salt (NaCl).
Elements: Made up of only one kind of atoms. Cannot be broken down into simpler substances. Example: Iron, Copper.
Compounds: Made up of more than one kind of atoms combined chemically. Can be broken down into elements by chemical reactions. Example: Water (H2O), Salt (NaCl).
Question No. 15: Explain Tyndall effect and Brownian movement with suitable diagram.
Answer:
Tyndall effect: When a strong beam of light is passed through a colloidal solution, the path of the light becomes visible. This is known as Tyndall effect. The scattered light illuminates the path of the beam.
Brownian movement: When colloidal solutions are viewed under a powerful microscope, the colloidal particles are seen to move in a continuous, fast, zig-zag motion.
Tyndall effect: When a strong beam of light is passed through a colloidal solution, the path of the light becomes visible. This is known as Tyndall effect. The scattered light illuminates the path of the beam.
Brownian movement: When colloidal solutions are viewed under a powerful microscope, the colloidal particles are seen to move in a continuous, fast, zig-zag motion.
Unit 17: Animal Kingdom (June Portion)
Question No. 16: Define taxonomy.
Answer: Taxonomy is the branch of biology that deals with the classification of living organisms.
Question No. 17: What is nematocyst?
Answer: Coelenterates have stinging cells called cnidoblasts or nematocysts for defense and capturing prey.
Question No. 18: Why coelenterates are called diploblastic animals?
Answer: They are called diploblastic because their body wall is made up of two layers: the outer ectoderm and the inner endoderm.
Question No. 19: List the respiratory organs of amphibians.
Answer: Respiration is through gills, lungs, skin and buccopharyngeal cavity.
Question No. 20: Why are frogs said to be amphibians?
Answer: They are cold-blooded vertebrates that have a dual life, living both on land and in water.
Question No. 21: Differentiate between flat worms and round worms?
Answer: Flat worms (Platyhelminthes) are dorso-ventrally flattened and mostly endoparasites. Round worms (Aschelminthes) are unsegmented, cylindrical and have a pseudocoelom.
Question No. 22: List five characteristic features of fishes.
Answer:
(1) Aquatic, poikilothermic (cold-blooded) vertebrates.
(2) Body is covered by scales.
(3) Locomotion is by paired and unpaired fins.
(4) Respiration is by gills.
(5) Heart is two-chambered.
(1) Aquatic, poikilothermic (cold-blooded) vertebrates.
(2) Body is covered by scales.
(3) Locomotion is by paired and unpaired fins.
(4) Respiration is by gills.
(5) Heart is two-chambered.
Unit 2: Motion (July Portion - 50%)
Question No. 23: Define velocity.
Answer: Velocity is the rate of change of displacement. Its SI unit is ms–1.
Question No. 24: Distinguish distance and displacement.
Answer:
Distance: The total length of the path travelled by the body. It is a scalar quantity.
Displacement: The shortest distance from the initial position to the final position of the body. It is a vector quantity.
Distance: The total length of the path travelled by the body. It is a scalar quantity.
Displacement: The shortest distance from the initial position to the final position of the body. It is a vector quantity.
Question No. 25: What do you mean by uniform motion?
Answer: A body is said to be in uniform motion if it covers equal distances in equal intervals of time.
Question No. 26: What do you understand about negative acceleration?
Answer: If velocity decreases with time, the acceleration is negative and it is called retardation or deceleration.
Question No. 27: A racing car has a uniform acceleration of 4 ms–2. What distance it covers in 10 s after the start?
Answer: Given: Initial velocity u = 0. Acceleration a = 4 ms–2. Time t = 10 s. Distance s = ut + ½ at2. s = 0 + ½ (4)(10)2 = 2 (100) = 200 m.
Unit 11: Atomic Structure (July Portion - 50%)
Question No. 28: How was it shown that atom has empty space?
Answer: In Rutherford's gold foil experiment, most of the alpha particles passed straight through the foil, showing that most of the space within the atoms is empty.
Question No. 29: What are nucleons?
Answer: Protons and neutrons are collectively called nucleons.
Question No. 30: Calculate the number of neutrons, protons and electrons for atomic number 3 and mass number 7.
Answer: Atomic Number (Z) = 3 (Protons = 3, Electrons = 3). Mass Number (A) = 7. Number of neutrons = A – Z = 7 – 3 = 4.
Question No. 31: Explain the postulates of Bohr's atomic model.
Answer:
(1) In an atom, the electrons revolve around the nucleus in fixed circular paths called orbits or shells or energy levels.
(2) While revolving in a particular orbit, an electron does not lose or gain energy.
(3) The orbits are designated as K, L, M, N... or 1, 2, 3, 4...
(1) In an atom, the electrons revolve around the nucleus in fixed circular paths called orbits or shells or energy levels.
(2) While revolving in a particular orbit, an electron does not lose or gain energy.
(3) The orbits are designated as K, L, M, N... or 1, 2, 3, 4...
Kalvi Mini First Midterm Exam 2026 - Model Question Paper
Time: 1.5 Hours | Max Marks: 50
PART-I: Choose the Correct Answer (5 x 1 = 5 Marks)
Question No. 1: Which among the following is not a device to measure mass?
a. Spring balance b. Beam balance c. Physical balance d. Digital balance
a. Spring balance b. Beam balance c. Physical balance d. Digital balance
Question No. 2: The area under velocity – time graph represents the:
a) velocity b) displacement c) speed d) acceleration
a) velocity b) displacement c) speed d) acceleration
Question No. 3: Among the following ___________ is a mixture:
a) Common Salt b) Juice c) Carbon dioxide d) Pure Silver
a) Common Salt b) Juice c) Carbon dioxide d) Pure Silver
Question No. 4: The Big Bang occurred _____ years ago:
a) 13.7 billion b) 15 million c) 15 billion d) 20 million
a) 13.7 billion b) 15 million c) 15 billion d) 20 million
Question No. 5: Elements in the modern periodic table are arranged in:
a) 18 groups and 7 periods b) 7 groups and 18 periods
a) 18 groups and 7 periods b) 7 groups and 18 periods
PART-II: Short Answers (5 x 2 = 10 Marks)
Question No. 6: Define standard unit.
Question No. 7: Define velocity.
Question No. 8: What is meant by sublimation?
Question No. 9: List the respiratory organs of amphibians.
Question No. 10: Calculate the number of nucleons in Phosphorus (Atomic number 15, Mass number 31).
PART-III: Detailed / Paragraph Answers / Problems (5 x 5 = 25 Marks)
Question No. 11: Write the rules that are followed in writing the symbols of units in SI system (5 points).
Question No. 12: Differentiate between mass and weight.
Question No. 13: Explain different types of motion with examples.
Question No. 14: Write the differences between elements and compounds.
Question No. 15: Explain the postulates of Bohr's atomic model.
PART-IV: Diagram-based / Numerical Questions (2 x 5 = 10 Marks)
Question No. 16: A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 ms–2, with what velocity will it strike the ground? After what time will it strike the ground?
Question No. 17: Explain Tyndall effect and Brownian movement with suitable diagram.
Kalvi Mini First Midterm Exam 2026 - Answer Key
PART-I
Question No. 1: a. Spring balance
Question No. 2: b) displacement covered by the moving object
Question No. 3: b) Juice
Question No. 4: a) 13.7 billion
Question No. 5: a) 18 groups and 7 periods
PART-II
Question No. 6: A unit is the fundamental quantity with which unknown quantities are compared.
Question No. 7: Velocity is the rate of change of displacement.
Question No. 8: The process by which a solid changes directly into a gas without passing through the liquid state.
Question No. 9: Gills, lungs, skin and buccopharyngeal cavity.
Question No. 10: Nucleons = Mass Number = 31.
PART-III
Question No. 11: (1) Units named after scientists are not written with a capital initial letter. (2) Symbols named after scientists are capital letters. (3) Small letters are used for other symbols. (4) No punctuation marks within symbols. (5) Symbols are not pluralized.
Question No. 12: Mass is the amount of matter; Weight is the gravitational pull. Mass is a scalar; Weight is a vector. Mass is measured by physical balance; Weight by spring balance.
Question No. 13: Linear motion: straight line. Circular motion: circular path. Oscillatory motion: repetitive to and fro motion. Random motion: no specific path.
Question No. 14: Elements contain one kind of atom; Compounds contain more than one kind combined chemically. Elements cannot be broken down; Compounds can be broken down by chemical reactions.
Question No. 15: Electrons revolve in fixed circular paths called orbits. While in an orbit, energy is constant. Orbits are K, L, M, N...
PART-IV
Question No. 16: u = 0, s = 20 m, a = 10 ms–2. v2 = u2 + 2as => v2 = 0 + 2(10)(20) = 400. v = 20 ms–1. v = u + at => 20 = 0 + 10(t) => t = 2 s.
Question No. 17: Tyndall effect: Scattering of a beam of light by colloidal particles making the path visible. Brownian movement: Continuous zig-zag motion of colloidal particles.
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