10th Science Quarterly Exam 2026 Question Paper & Answer Key | Dindigul District (EM)
Ace your revision with the official Dindigul District 10th Science Quarterly Exam 2026 Question Paper and Answer Key specifically compiled for English Medium students. This dedicated resource is designed to help you verify your answers, analyze the latest exam patterns, and identify key topics to strengthen your preparation for the upcoming Tamil Nadu public board examinations.
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QUARTERLY EXAMINATION - 2026
1. Impulse is equal to:
a) rate of change of momentum b) rate of force and time
c) change of momentum d) rate of change of mass
Explanation: Impulse J = F × Δt = Δp (change in linear momentum).
2. Amount of light entering into the eye is controlled by:
a) Sclera b) Retina c) Iris d) Cornea
Explanation: The iris regulates the size of the pupil, thereby adjusting the amount of light entering the eye.
3. If a substance is heated or cooled, the change in mass of that substance is:
a) Positive b) Negative c) Zero d) None of the above
Explanation: Thermal expansion or contraction changes volume and density, but total mass remains strictly conserved.
4. Mass of 1 mole of Nitrogen atom is:
a) 28 amu b) 14 amu c) 28 g d) 14 g
Explanation: The molar mass of a nitrogen atom (N) is 14 g/mol (note: nitrogen molecule N2 is 28 g).
5. The number of periods and groups in the periodic table are:
a) 6, 16 b) 7, 17 c) 8, 18 d) 7, 18
6. Identify the non-aqueous solution:
a) sodium chloride in water b) glucose in water
c) copper sulphate in water d) sulphur in carbon-di-sulphide
Explanation: Solutions where the solvent is other than water are non-aqueous solutions.
7. The endarch condition is the characteristic feature of:
a) root b) stem c) leaves d) flower
8. Mammals are _______ animals.
a) cold blooded b) warm blooded c) Poikilothermic d) all the above
9. Which of the following processes requires energy?
a) active transport b) diffusion c) Osmosis d) all of them
Explanation: Active transport expends ATP energy to pump substances against their concentration gradient.
10. Node of Ranvier is found in:
a) muscles b) axons c) dendrites d) cyton
Explanation: The periodic gaps where the myelin sheath is absent along the axon are called Nodes of Ranvier.
11. Avena coleoptile test was conducted by:
a) Darwin b) N. Smit c) Paal d) F.W. Went
12. The _______ units form the backbone of the DNA.
a) 5 Carbon Sugar b) Phosphate c) Nitrogenous bases d) Sugar phosphate
13. State Newton's Second law.
The force acting on a body is directly proportional to the rate of change of linear momentum of the body and the change in momentum takes place in the direction of the force.
Formula: F = ma.
14. Distinguish between linear, areal or superficial expansion.
• Linear Expansion: Increase in length of a solid body due to heating (ΔL / L0 = αL ΔT).
• Superficial (Areal) Expansion: Increase in surface area of a solid body due to heating (ΔA / A0 = αA ΔT).
15. Define - Atomicity.
The number of atoms present in one molecule of an element, compound, or substance is called its atomicity (e.g., O2 = 2, O3 = 3, P4 = 4).
16. What is rust? Give the equation for formation of rust.
When iron is exposed to moist air containing oxygen and water, it slowly forms a reddish-brown flaky coating of hydrated ferric oxide called rust.
Chemical Equation: 4Fe + 3O2 + xH2O → 2Fe2O3 · xH2O (Rust).
17. The aquatic animals live more in cold region. Why?
The solubility of oxygen gas in water increases as temperature decreases. Cold water contains a higher concentration of dissolved oxygen, allowing aquatic animals to breathe easily and thrive in larger numbers.
18. Name the three basic tissue systems in flowering plants.
Sachs (1875) classified tissue systems into:
1. Dermal or Epidermal tissue system
2. Ground or Fundamental tissue system
3. Vascular tissue system
19. How is diastema formed in rabbit?
In rabbit, canine teeth are completely absent in both upper and lower jaws. The toothless space or gap that separates the biting incisors from the grinding premolars is known as diastema.
20. Transpiration is a necessary evil in plants. Explain.
Transpiration causes potential water loss (often causing wilting under dry conditions), but it is vital because it creates a suction pull for the ascent of sap (transport of water and minerals), maintains cell turgidity, and produces a cooling effect for the plant body. Hence, Curtis called it a "necessary evil".
21. Draw the structure of Adrenal gland and label its parts.
Diagram showing the adrenal gland positioned like a cap on the upper pole of the kidney.
Key Parts:
1. Adrenal Cortex — Outer yellowish region.
2. Adrenal Medulla — Inner central reddish-brown region.
22. [Compulsory] Calculate the resistance of a conductor through which a current of 2 A passes, when the potential difference between its ends is 30 V.
Given: Potential difference V = 30 V, Current I = 2 A.
According to Ohm's Law: R = V / I
R = 30 / 2 = 15 Ω (ohm)
23. Describe rocket propulsion.
• Principle: Rocket propulsion is based on Newton's third law of motion and the law of conservation of linear momentum.
• Working: Inside the combustion chamber, propellants are burned to produce high-pressure hot gases that escape through the tail nozzle at supersonic speeds (Action).
• This produces an equal and opposite forward reaction thrust that propels the rocket upward (Reaction).
• As fuel burns, the mass of the rocket decreases continuously, which leads to a progressive increase in acceleration.
24. Differentiate the eye defects: Myopia and Hypermetropia.
| Feature | Myopia (Short-sightedness) | Hypermetropia (Long-sightedness) |
|---|---|---|
| Vision | Nearby objects are clear; distant objects appear blurred. | Distant objects are clear; nearby objects appear blurred. |
| Cause | Elongation of eyeball / excessive lens curvature. | Shortening of eyeball / focal length too long. |
| Image focus | Formed in front of the retina. | Formed behind the retina. |
| Correction | Corrected using a concave lens. | Corrected using a convex lens. |
25. Give the salient features of "Modern atomic theory".
1. An atom is no longer indivisible; it is composed of subatomic particles (electrons, protons, and neutrons).
2. Atoms of the same element may have different atomic masses (Isotopes: 17Cl35, 17Cl37).
3. Atoms of different elements may have the same atomic mass (Isobars: 18Ar40, 20Ca40).
4. Atoms of one element can be transformed into atoms of another element (Artificial transmutation).
5. Mass of an atom can be converted into energy (E = mc2).
26. i) Define the term solution. ii) Classify the following substances into deliquescent and hygroscopic: Conc. sulphuric acid, copper sulphate pentahydrate, silica gel, calcium chloride, and gypsum salt.
i) Solution: A homogeneous mixture of two or more substances.
ii) Classification:
• Hygroscopic substances: Conc. sulphuric acid (H2SO4), Silica gel, Copper sulphate pentahydrate (CuSO4 · 5H2O), Gypsum salt (CaSO4 · 2H2O).
• Deliquescent substances: Calcium chloride (CaCl2).
27. List out the parasitic adaptations in leech.
1. Anterior and posterior suckers provide strong attachment to the host's body and assist in sucking blood.
2. Three muscular jaws make a painless Y-shaped triradiate wound on the host's skin.
3. Salivary secretion contains hirudin, an anticoagulant that prevents blood from clotting.
4. The crop has 10 pairs of lateral diverticula to store large volumes of sucked blood for several months.
28. i) Why is the circulation in man referred to as double circulation? ii) What is the importance of valves in the heart?
i) Double circulation: Blood circulates through the human heart twice in one complete cycle:
1. Pulmonary circulation: Deoxygenated blood travels from right ventricle to lungs and returns oxygenated to left atrium.
2. Systemic circulation: Oxygenated blood travels from left ventricle to all body parts and deoxygenated blood returns to right atrium.
ii) Importance of valves: Ensure unidirectional blood flow through the heart chambers and prevent backward flow (regurgitation).
29. Classify neurons based on their structure.
1. Unipolar neurons: Only one process arises from the cyton, which functions as both axon and dendron (found in embryonic stages).
2. Bipolar neurons: Two processes arise from opposite ends of the cyton — one axon and one dendron (found in the retina of the eye).
3. Multipolar neurons: Many dendrons and a single long axon arise from the cyton (found in the cerebral cortex).
30. Write the physiological effects of gibberellins.
1. Stimulates extraordinary internodal elongation in genetically dwarf plants (corn, pea).
2. Promotes sudden stem elongation followed by flowering in rosette plants, known as bolting.
3. Promotes the production of male flowers in monoecious plants.
4. Breaks the dormancy of potato tubers and seeds.
5. Induces parthenocarpy to produce seedless fruits (e.g., seedless grapes).
31. With a neat labelled diagram describe the parts of a typical angiospermic ovule.
1. Funicle: Stalk attaching the ovule to the placenta.
2. Hilum: Point of attachment between the funicle and ovule body.
3. Nucellus: Central nutritive tissue made of parenchymatous cells.
4. Integuments: Outer and inner protective envelopes surrounding the nucellus.
5. Micropyle: Small apical pore left uncovered by integuments for pollen tube entry.
6. Chalaza: Basal region where integuments and nucellus join.
7. Embryo Sac: Female gametophyte containing an egg apparatus (1 egg + 2 synergids) at the micropylar end, 3 antipodals at the chalazal end, and 2 polar nuclei at the centre.
32. [Compulsory] Calcium Carbonate is decomposed on heating by the following reaction:
CaCO3 → CaO + CO2 (on heating)
i) How many moles of calcium carbonate are involved in this reaction?
ii) Calculate the gram molecular mass of calcium carbonate involved in this reaction.
i) Number of moles:
From the balanced chemical equation, the stoichiometric coefficient of CaCO3 is 1. Hence, 1 mole of calcium carbonate is involved in this reaction.
ii) Gram molecular mass of CaCO3 (Ca = 40, C = 12, O = 16):
Gram molecular mass = (1 × 40) + (1 × 12) + (3 × 16) = 40 + 12 + 48 = 100 g
i) Newton's Universal Law of Gravitation:
Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Mathematical Expression:
Let two bodies of masses m1 and m2 be separated by a distance r.
F ∝ m1m2 and F ∝ 1 / r2
F = (G · m1 · m2) / r2
(where G is the Universal Gravitational Constant, G = 6.674 × 10−11 N m2 kg−2).
ii) Applications:
1. Helps in calculating the dimensions, mass of celestial bodies, stars, and planets.
2. Helps discover new stars and planets by observing wobbling (irregularities) in planetary motions.
3. Explains the phenomenon of tides caused by gravitational pull of the moon and sun.
4. Explains geotropism (root growth towards gravity) in plants.
i) Electric current: The rate of flow of electric charges in a conductor (I = Q / t).
ii) Unit: The SI unit is ampere (A).
Definition of Ampere: If 1 coulomb of electric charge flows across any cross-section of a conductor in 1 second, the current flowing through it is 1 ampere (1 A = 1 C / 1 s).
iii) Measurement:
• Instrument: Ammeter.
• Connection: Must always be connected in series with the electrical component so that all the current to be measured flows through it.
i) Applications of Avogadro's law:
1. Explains Gay-Lussac's law of combining volumes.
2. Determines the atomicity of elementary gases.
3. Establishes the relationship: Molecular Mass = 2 × Vapour Density.
4. Establishes that 1 mole of any gas at STP occupies 22.4 litres (molar volume).
ii) Differences between Atoms and Molecules:
| Atom | Molecule |
|---|---|
| Smallest unit of an element. | Smallest unit of an element or compound. |
| Cannot exist independently in free state (except noble gases). | Can exist independently in free state. |
| Highly reactive (except noble gases). | Less reactive than atoms. |
| No chemical bonds within it. | Atoms in a molecule are held together by chemical bonds. |
i) Factors affecting solubility:
1. Nature of solute and solvent: "Like dissolves like". Polar solutes dissolve in polar solvents (e.g., NaCl in water), while non-polar substances dissolve in non-polar solvents.
2. Temperature:
• Endothermic dissolution: Solubility increases with increasing temperature.
• Exothermic dissolution: Solubility decreases with increasing temperature.
• Solubility of gases in liquids decreases with rising temperature.
3. Pressure: Significant only for gases in liquids; an increase in pressure increases gas solubility (Henry's Law).
ii) Heating of Epsom salt:
When magnesium sulphate heptahydrate (MgSO4 · 7H2O) crystals are heated, they lose all seven molecules of water of crystallization to become anhydrous magnesium sulphate (MgSO4):
MgSO4 · 7H2O ↔ MgSO4 + 7H2O (Heating / Cooling)
| Feature | Light Dependent Reaction (Hill Reaction) | Light Independent Reaction (Calvin Cycle) |
|---|---|---|
| Light Requirement | Directly requires sunlight energy. | Does not require direct sunlight. |
| Site of Occurrence | Grana (Thylakoid membranes) of chloroplast. | Stroma of chloroplast. |
| Reactants | Water (H2O), Light, NADP, ADP. | CO2, ATP, and NADPH2. |
| End Products | Oxygen (O2), ATP, and NADPH2. | Carbohydrates (Glucose / Starch), ADP, NADP. |
• Structural Organisation of DNA (Watson & Crick Model):
1. DNA is a double helix consisting of two complementary polynucleotide chains running in anti-parallel directions (5' → 3' and 3' → 5').
2. The backbone consists of alternating deoxyribose sugar and phosphate units linked by phosphodiester bonds.
3. Nitrogenous bases face inward: Adenine pairs with Thymine via two hydrogen bonds (A = T), and Guanine pairs with Cytosine via three hydrogen bonds (G ≡ C).
4. Each complete turn of the double helix measures 3.4 nm (34 Å) and contains 10 base pairs, with a distance of 0.34 nm (3.4 Å) between adjacent pairs.
• Biological Significance of DNA:
1. Heredity: Stores and accurately transmits genetic information from parents to offspring.
2. Protein Synthesis: Encodes specific codons that direct the synthesis of enzymes and structural proteins.
3. Cellular Regulation: Directs growth, metabolism, and development of all living organisms.
4. Mutation and Evolution: Recombination and occasional replication errors provide variations necessary for biological evolution.
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