10th Science Quarterly Exam Question Paper & Answer Key 2026 | Tenkasi District (EM)

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Enhance your board exam preparation with the official 10th Standard Science Quarterly Exam 2026 Question Paper and Answer Key released for Tenkasi District (English Medium). This targeted study resource features the authentic regional examination paper alongside comprehensive, step-by-step solutions for Physics, Chemistry, and Biology. Testing yourself with this actual district paper allows English medium students to identify key question trends, refine their time management, and build solid confidence for the final board exams.

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10th Science Quarterly Exam Question Paper & Answer Key 2026 | Tenkasi District (EM)

Tsi10S • Tenkasi District Standard 10 Reg. No.: [___________]

Common Quarterly Examination - September 2026

SCIENCE (ENGLISH MEDIUM) • QUESTION PAPER & COMPLETE SOLUTIONS

Date: 23-09-2026 Time: 3.00 Hrs. Marks: 75

Part - I • Answer all the questions. Choose the correct answer: 12 × 1 = 12

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

Answer: c) change of momentum
Explanation: Impulse J = F × Δt = Δp (change in linear momentum).

2) The least count of travelling microscope is:
a) 0.01 cm b) 0.01 mm c) 0.1 cm d) 0.1 mm

Answer: b) 0.01 mm (or 0.001 cm)

3) Kilowatt hour is the unit of:
a) resistivity b) conductivity c) electrical energy d) electrical power

Answer: c) electrical energy
Explanation: 1 kWh is the commercial unit of electrical energy (1 kWh = 3.6 × 10⁶ J).

4) The gram molecular mass of oxygen molecule is:
a) 16g b) 18g c) 32g d) 17g

Answer: c) 32g
Explanation: Oxygen molecule is diatomic (O₂), molecular mass = 2 × 16 = 32 g.

5) _______ is an important metal to form amalgam.
a) Ag b) Hg c) Mg d) Al

Answer: b) Hg (Mercury)

6) Solubility of ammonia gas is:
a) 36g/100g water b) 80g/100g water c) 48g/100g water d) 91g/100g water

Answer: c) 48g/100g water (at 25°C)

7) The xylem and phloem arranged side by side on same radius is called:
a) radial b) amphivasal c) conjoint d) None of these

Answer: c) conjoint

8) The wall of human heart is made of:
a) Endocardium b) Epicardium c) Myocardium d) All of the above

Answer: d) All of the above

9) There are _______ pairs of cranial nerves and _______ pairs of spinal nerves.
a) 12, 31 b) 31, 12 c) 12, 13 d) 12, 21

Answer: a) 12, 31

10) Which organ acts as both exocrine gland as well as endocrine gland?
a) Pancreas b) Kidney c) Liver d) Lungs

Answer: a) Pancreas (Dual gland / Heterocrine gland)

11) World Menstrual Hygiene day observed on:
a) January 28 b) March 28 c) May 28 d) December 28

Answer: c) May 28

12) Okazaki fragments are joined together by:
a) Helicase b) DNA Polymerase c) RNA Primer d) DNA Ligase

Answer: d) DNA Ligase

Part - II • Answer any seven questions. (Q.No. 22 is compulsory): 7 × 2 = 14

13) Define dispersion of light.

Answer:
When a beam of white light or composite light is refracted through any transparent medium like glass prism, it splits into its seven constituent colors (VIBGYOR). This phenomenon is known as dispersion of light.

14) State Avogadro's law.

Answer:
Avogadro's law states that equal volumes of all gases under the same conditions of temperature and pressure contain equal number of molecules.
Formula: V ∝ n (or V / n = Constant).

15) Write about the uses of copper.

Answer:
1. Used extensively in manufacturing electrical cables, wiring, and telecommunication lines due to high electrical conductivity.
2. Used for making cooking utensils, calorimeters, and heat exchangers.
3. Used in making alloys like brass (Cu + Zn) and bronze (Cu + Sn) and for minting coins.

16) The aquatic animals live more in cold regions. Why?

Answer:
The solubility of gases in liquids increases with decrease in temperature. Hence, cold water contains a higher concentration of dissolved oxygen, allowing aquatic animals to breathe comfortably and survive in large numbers.

17) What is respiratory quotient?

Answer:
Respiratory quotient (RQ) is the ratio of the volume of carbon dioxide released to the volume of oxygen consumed during respiration.
Formula: RQ = Volume of CO₂ liberated / Volume of O₂ consumed.

18) State whether True or False. If false write the correct statement:
a) Diastema is a gap between premolar and molar teeth in rabbit.
b) Plants lose water by the process of transpiration.

Answer:
a) False. Correct statement: Diastema is a toothless gap between incisors and premolars in rabbit due to the absence of canines.
b) True.

19) Name the parts of hindbrain.

Answer:
The hindbrain consists of: 1. Cerebellum 2. Pons 3. Medulla oblongata.

20) Draw a picture of adrenal gland and label the parts.

Answer:
Draw the crescent/cap-shaped adrenal gland situated above the kidney.
Main Parts:
1. Adrenal Cortex — Outer yellowish region (subdivided into Zona glomerulosa, Zona fasciculata, and Zona reticularis).
2. Adrenal Medulla — Inner central dark reddish-brown region consisting of chromaffin cells.

21) Match the following:
i) Fission — Hydra
ii) Budding — Spirogyra
iii) Fragmentation — Yeast
iv) Regeneration — Amoeba

Correct Match:
i) Fission — Amoeba
ii) Budding — Yeast (or Hydra)
iii) Fragmentation — Spirogyra
iv) Regeneration — Hydra (or Planaria)

22) [Compulsory] Find the effective resistance of the given circuit across terminals AC:
[Circuit: Two 5 Ω resistors in series along branch ABC, connected in parallel with a 10 Ω resistor along branch AC]

Solution:
Along upper path ABC, two 5 Ω resistors are in series:
R_series = 5 Ω + 5 Ω = 10 Ω.
This combination is connected in parallel with the 10 Ω resistor along branch AC:
1 / R_AC = (1 / 10) + (1 / 10) = 2 / 10 = 1 / 5 Ω⁻¹.
Effective Resistance across AC = 5 Ω.

Part - III • Answer any seven questions. (Q.No. 32 is compulsory): 7 × 4 = 28

23) Differentiate mass and weight.

Mass	Weight
Quantity of matter contained in a body.	Gravitational force exerted on a body (W = mg).
Fundamental physical quantity.	Derived physical quantity.
Scalar quantity.	Vector quantity.
SI unit is Kilogram (kg).	SI unit is Newton (N).
Remains constant everywhere.	Varies from place to place depending on 'g'.

24) a) Write about the uses of a simple microscope. b) State Charles's law.

Answer:
a) Uses of simple microscope:
1. Used by watchmakers and jewelers to view minute gears and components.
2. Used to read small letters, palmistry, and skin examination in biology labs.
b) Charles's Law:
According to Charles's law, when the pressure of a gas is kept constant, the volume of a gas is directly proportional to the absolute temperature of the gas (V / T = Constant).

25) List the merits of LED bulbs.

Answer:
1. Energy efficient — consumes significantly less electrical power compared to incandescent and CFL bulbs.
2. Long lifespan (lasts up to 25 to 50 times longer).
3. Eco-friendly — does not contain toxic elements like mercury.
4. Produces negligible heat loss and turns on instantly without warm-up time.

26) a) State two conditions necessary for rusting of iron. b) State Henry's law.

Answer:
a) Conditions for rusting:
1. Presence of oxygen (air).
2. Presence of water (moisture).
b) Henry's Law:
Henry's law states that at constant temperature, the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid surface (S ∝ P).

27) Differentiate between Monocot root and Dicot root.

Anatomical Feature	Dicot Root	Monocot Root
Xylem vessels	Tetrarch (usually four xylem bundles)	Polyarch (many xylem bundles)
Cambium	Present (develops during secondary growth)	Absent
Secondary growth	Present	Absent
Pith	Absent	Present
Conjunctive tissue	Parenchymatous	Sclerenchymatous

28) a) Write the dental formula of rabbit. b) What are corpora quadrigemina?

Answer:
a) Dental formula of rabbit: (I 2/1, C 0/0, PM 3/2, M 3/3) or 2033 / 1023.
b) Corpora quadrigemina: The dorsal surface of the midbrain consists of four rounded lobes/swellings called corpora quadrigemina. They control visual and auditory reflexes.

29) How are arteries and veins structurally different from one another?

Arteries	Veins
Thick, elastic, and muscular walls.	Thin, non-elastic walls.
Narrow internal lumen.	Wide internal lumen.
Valves are absent.	Valves are present to prevent backward flow.
Carry blood away from the heart at high pressure.	Carry blood towards the heart at low pressure.

30) Name the gaseous plant hormone. Describe its three different actions in plants.

Answer:
Gaseous hormone: Ethylene.
Three actions:
1. Promotes the ripening of fleshy fruits (like banana, apple, mango).
2. Stimulates the formation of abscission zone in leaves, flowers, and fruits, leading to premature shedding.
3. Breaks the dormancy of buds, seeds, and storage tubers.

31) a) Define triple fusion. b) What are Okazaki fragments?

Answer:
a) Triple fusion: The fusion of one haploid male gamete (n) with the diploid secondary nucleus (2n) inside the embryo sac to form a triploid primary endosperm nucleus (3n) is called triple fusion.
b) Okazaki fragments: During DNA replication, short segments of DNA synthesized discontinuously along the lagging strand (3' to 5' direction) are called Okazaki fragments. They are later joined together by DNA ligase.

32. [Compulsory] Calculate the number of moles in: (i) 27 g of Al (ii) 1.51 × 10²³ molecules of NH₄Cl.

Solution:
(i) 27 g of Al (Atomic mass of Al = 27 g/mol):
Number of moles = Mass / Atomic mass = 27 / 27 = 1 mole.

(ii) 1.51 × 10²³ molecules of NH₄Cl:
Number of moles = Number of molecules / Avogadro's number
= (1.51 × 10²³) / (6.023 × 10²³) = 1.51 / 6.023 ≈ 0.25 mole.

Part - IV • Answer all the questions. Draw diagrams wherever necessary: 3 × 7 = 21

33. a) i) Describe rocket propulsion. ii) What are the causes of "Myopia"?

Answer:
i) Rocket Propulsion:
• Works on Newton's third law of motion and the law of conservation of linear momentum.
• When fuel in the combustion chamber is ignited, highly compressed hot gases rush out through the nozzle at the rear end with extreme velocity (Action).
• This produces an equal and opposite upward thrust/reaction force pushing the rocket forward (Reaction).
• As the rocket moves upward, its mass continuously decreases due to fuel combustion, resulting in a continuous increase in acceleration.
ii) Causes of Myopia (Short-sightedness):
1. Elongation of the eyeball from front to back.
2. Excessive curvature of the eye lens (decrease in focal length).
Correction: Corrected using a concave lens of appropriate focal length.

(OR) 33. b) i) Derive the ideal gas equation. ii) Define 1 volt.

Answer:
i) Derivation of Ideal Gas Equation:
• According to Boyle's law: PV = constant (or V ∝ 1/P)
• According to Charles's law: V / T = constant (or V ∝ T)
• According to Avogadro's law: V / n = constant (or V ∝ n)
Combining these three gas laws: PV / nT = Constant
Since number of moles n = μ N_A, we have PV / (μ N_A T) = k_B (Boltzmann constant).
PV = μ N_A k_B T.
Defining Universal Gas Constant R = N_A k_B (8.31 J mol⁻¹ K⁻¹), for 1 mole of gas:
PV = RT.
ii) Definition of 1 Volt:
The potential difference between two points is said to be 1 volt if 1 joule of work is done in moving a positive charge of 1 coulomb from one point to another against the electrostatic force (1 Volt = 1 Joule / 1 Coulomb).

34. a) i) Define atomicity. ii) Explain the smelting process in metallurgy.

Answer:
i) Atomicity: The number of atoms present in one molecule of an element or compound is called its atomicity (e.g., O₂ = 2, O₃ = 3, P₄ = 4).
ii) Smelting Process:
Smelting is the process of reducing roasted oxide ore into molten metal using a reducing agent (coke) and flux at temperatures above the melting point of the metal inside a blast furnace.
Example (Extraction of Iron):
• Roasted haematite ore (Fe₂O₃), coke (C), and limestone (CaCO₃) are loaded in the ratio 8:4:1.
• Carbon monoxide reduces iron oxide: Fe₂O₃ + 3CO → 2Fe + 3CO₂.
• Flux (CaO from decomposed CaCO₃) combines with silica gangue (SiO₂) to form fusible slag: CaO + SiO₂ → CaSiO₃ (Slag).

(OR) 34. b) i) In what way do hygroscopic substances differ from deliquescent substances? ii) Calculate the gram molecular mass of CO₂.

Answer:
i) Differences:

Hygroscopic Substances	Deliquescent Substances
Absorb moisture from air without dissolving.	Absorb sufficient moisture from air and dissolve in it.
Do not change their physical state.	Change their physical state (solid turns to liquid).
Can be amorphous solids or liquids.	Typically crystalline solids.
E.g., Conc. H₂SO₄, Silica gel, Quicklime.	E.g., NaOH, KOH, FeCl₃.

ii) Gram molecular mass of CO₂:
Atomic mass of Carbon (C) = 12 g, Atomic mass of Oxygen (O) = 16 g
Molecular mass of CO₂ = (1 × 12) + (2 × 16) = 12 + 32 = 44 g.

35. a) i) How is diastema formed in rabbit? ii) With a neat labelled diagram, explain the structure of a neuron.

Answer:
i) Formation of Diastema:
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. It helps in the manipulation, chewing, and grinding of food.
ii) Structure of a Neuron:
1. Cyton (Cell body / Soma): Central spherical body with granular cytoplasm (neuroplasm), a large nucleus, and protein-synthesizing Nissl's granules.
2. Dendrites (Dendrons): Multiple, short, branched projections emerging from the cyton that receive nerve impulses from other neurons and conduct them towards the cell body.
3. Axon: A single, long, cylindrical cytoplasmic fiber arising from the axon hillock that carries impulses away from the cyton. Covered by Schwann cells forming a protective lipid myelin sheath interrupted by regular gaps called Nodes of Ranvier. Ends in branched telodendria with terminal knobs that secrete neurotransmitters at the synapse.

(OR) 35. b) i) What is bolting? How can it be induced artificially? ii) With a neat labelled diagram, describe the parts of a typical angiospermic ovule.

Answer:
i) Bolting:
Bolting is the sudden, rapid elongation of internodes followed by flowering in plants showing rosette growth habit (e.g., cabbage, beet).
Artificial Induction: It can be induced artificially by the external application of the plant growth hormone gibberellin.
ii) Parts of a typical Angiospermic Ovule (Anatropous Ovule):
1. Funiculus (Funicle): The stalk connecting the ovule to the placenta.
2. Hilum: The point of attachment where the funicle joins the body of the ovule.
3. Integuments: Outer and inner protective cellular envelopes surrounding the central tissue.
4. Micropyle: A narrow apical opening left uncovered by integuments through which the pollen tube enters.
5. Chalaza: The swollen basal region of the ovule where integuments, funicle, and nucellus merge.
6. Nucellus: The massive central parenchymatous nutritive tissue.
7. Embryo Sac (Female Gametophyte): A 7-celled, 8-nucleate structure embedded in the nucellus containing:
• Egg apparatus: Located at the micropylar end, composed of one central egg cell (female gamete) and two supporting synergids.
• Central cell: Houses two polar nuclei that fuse to form a diploid secondary nucleus.
• Antipodals: Three vegetative cells situated at the chalazal end.