10th Science Quarterly Exam 2026 Question Paper & Answer Key

Optimize your study routine with the official Thiruvannamalai District 10th Science Quarterly Exam 2026 Question Paper and Answer Key compiled for English Medium students. This dedicated resource serves as an excellent evaluation tool, helping you review your answers, understand the district-level evaluation standards, and target key chapters effectively for the upcoming Tamil Nadu public board examinations.

QMS • TIRUVANNAMALAI DISTRICT 10-Std Reg. No.: [__________]

QUARTERLY EXAMINATION - 2026

SCIENCE (ENGLISH MEDIUM) • QUESTION PAPER & DETAILED SOLUTIONS

Time: 3.00 Hrs Marks: 75

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

1. One kilogram force equals to:
a) 9.8 dyne b) 9.8 × 10⁴ N c) 98 × 10⁴ dyne d) 980 dyne

Answer: c) 98 × 10⁴ dyne
Explanation: 1 kgf = 9.8 N. Since 1 N = 10⁵ dyne, 9.8 N = 9.8 × 10⁵ dyne = 98 × 10⁴ dyne.

2. If V_B, V_G, V_R be the velocity of blue, green and red light respectively in a glass prism, then which of the following statement gives the correct relation?
a) V_B = V_G = V_R b) V_B > V_G > V_R c) V_B < V_G < V_R d) V_B < V_G > V_R

Answer: c) V_B < V_G < V_R
Explanation: In a refractive medium, velocity increases with wavelength (λ_R > λ_G > λ_B). Thus, red light travels fastest and blue travels slowest.

3. In the given diagram, the possible direction of heat energy transformation is (Temperatures: A = 303 K, B = 304 K, C = 305 K):
a) A ← B, A ← C, B ← C b) A → B, A → C, B → C
c) A → B, A ↔ C, B → C d) A ← B, A → C, B ← C

Answer: a) A ← B, A ← C, B ← C
Explanation: Heat naturally flows from a body at higher temperature to a body at lower temperature (C [305 K] → B [304 K] → A [303 K]).

4. A charge of 12 coulomb flows through a bulb in 5 second. What is the current through the bulb?
a) 60A b) 17A c) 2.4A d) 24A

Answer: c) 2.4A
Solution: I = Q / t = 12 / 5 = 2.4 A.

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

Answer: c) 32 g
Explanation: Oxygen molecule (O₂) = 2 × 16 = 32 g.

6. Alloy used in the making of pressure cooker is:
a) Brass b) Bronze c) Magnalium d) Duralumin

Answer: d) Duralumin

7. Kreb's cycle takes place in:
a) chloroplast b) mitochondrial matrix c) stomata d) inner mitochondrial membrane

Answer: b) mitochondrial matrix

8. Which is the correct sequence of blood flow?
a) ventricle → atrium → vein → arteries b) atrium → ventricle → veins → arteries
c) atrium → ventricle → arteries → vein d) ventricles → vein → atrium → arteries

Answer: c) atrium → ventricle → arteries → vein

9. Which nervous band connects the two cerebral hemispheres of brain?
a) thalamus b) hypothalamus c) corpus callosum d) pons

Answer: c) corpus callosum

10. A single highly coiled tube where sperms are stored, get concentrated and mature is known as:
a) Epididymis b) Vasa efferentia c) Vas deferens d) Seminiferous tubules

Answer: a) Epididymis

11. The hormone which has positive effect on apical dominance is:
a) Cytokinin b) Auxin c) Gibberellin d) Ethylene

Answer: b) Auxin

12. Find the Correct pair:
a) Acrocentric — (i) The centromere is found near the centre of the chromosome with two unequal arms.
b) Sub-metacentric — (ii) The centromere is found on the proximal end.
c) Metacentric — (iii) The centromere occurs in the centre of the chromosome and forms two equal arms.
d) Telocentric — (iv) The centromere is found at one end with a short arm and a long arm.

Answer: c) Metacentric — (iii) The centromere occurs in the centre of the chromosome and forms two equal arms.

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

13. How does an astronaut float in a space shuttle?

Answer:
An astronaut does not float due to zero gravity. The space shuttle orbits Earth with very high orbital velocity and is in a state of continuous free fall towards Earth. As both the shuttle and astronaut accelerate equally towards Earth with acceleration equal to 'g', the apparent weight of the astronaut becomes zero, giving the experience of weightlessness and floating.

14. Differentiate a convex lens and a concave lens.

Convex Lens	Concave Lens
Thicker in the middle and thinner at edges.	Thinner in the middle and thicker at edges.
Converging lens.	Diverging lens.
Produces mostly real and inverted images.	Always produces virtual and erect images.

15. Define: Relative atomic mass.

Answer:
Relative atomic mass (A_r) of an element is defined as the ratio between the average mass of its isotopes to 1/12th part of the mass of a Carbon-12 atom.

16. A is a silvery-white metal. A reacts with O₂ at 800°C to form B. An alloy of A is used in making the aircraft. Find A and B.

Answer:
• Silvery-white metal A = Aluminium (Al)
• Compound B = Aluminium oxide (Al₂O₃)
Reaction: 4Al + 3O₂ → 2Al₂O₃ (at 800°C)

17. Give an example each: i) Gas in liquid ii) Solid in liquid iii) Solid in solid iv) Gas in gas.

Answer:
i) Gas in liquid — Soda water (CO₂ gas dissolved in water)
ii) Solid in liquid — Common salt (NaCl) in water
iii) Solid in solid — Alloys like brass (copper + zinc) or bronze
iv) Gas in gas — Air (mixture of oxygen, nitrogen, and other gases)

18. Identify the parts A, B, C and D in the given figure of stoma:
[Diagram: Open stomatal apparatus showing kidney-shaped guard cells, pore, and surrounding epidermal cells]

Answer:
A — Epidermal cell
B — Guard cell
C — Nucleus
D — Stomatal pore (or Chloroplast)

19. Fill in the blanks: i) _______ is ATP factory of the cells. ii) _______ and _______ increases the surface area of cerebrum.

Answer:
i) Mitochondria
ii) Gyri and sulci

20. Match the following:
1. Thyroxine — a. Acromegaly
2. Insulin — b. Tetany
3. Parathyroid hormone — c. Simple goitre
4. Growth hormone — d. Diabetes mellitus

Correct Match:
1. Thyroxine — c. Simple goitre
2. Insulin — d. Diabetes mellitus
3. Parathyroid hormone — b. Tetany
4. Growth hormone — a. Acromegaly

21. Write the characteristics of insect pollinated flowers.

Answer:
1. Flowers are brightly colored, showy, and large in size to attract insects.
2. Produce pleasant fragrances and sweet nectar as food rewards.
3. Pollen grains are large, rough, and have a spiny or sticky outer coat (pollenkitt) to cling to visiting insects.

22. [Compulsory] A beam of light passing through a diverging lens of focal length 0.3m appear to be focused at a distance 0.2m behind the lens. Find the position of the object.

Solution:
A diverging lens is a concave lens. Applying Cartesian sign convention:
Focal length f = −0.3 m
Image distance (virtual image on object side) v = −0.2 m
Using the Lens formula: 1 / f = 1 / v − 1 / u
1 / u = 1 / v − 1 / f = [1 / (−0.2)] − [1 / (−0.3)]
1 / u = −5 + (10 / 3) = −5/3 m⁻¹
u = −3 / 5 = −0.6 m
Answer: The object is placed at a distance of 0.6 m (or 60 cm) in front of the lens.

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

23. State Newton's laws of motion.

Answer:
• First Law: Every object continues to remain in its state of rest or of uniform motion along a straight line unless acted upon by an external unbalanced force.
• Second Law: The rate of change of linear momentum of a body is directly proportional to the applied force and takes place in the direction of the force (F = ma).
• Third Law: For every action, there is an equal and opposite reaction (F_A = −F_B).

24. Differentiate the eye defects: Myopia and Hypermetropia.

Feature	Myopia (Short-sightedness)	Hypermetropia (Long-sightedness)
Visual capability	Nearby objects are clear; distant objects are blurred.	Distant objects are clear; nearby objects are blurred.
Eyeball shape	Eyeball is elongated.	Eyeball is shortened.
Image focus	Focused in front of the retina.	Focused behind the retina.
Corrective lens	Corrected using a concave lens.	Corrected using a convex lens.

25. a) State Joule's law of heating. b) An alloy of nickel and chromium is used as the heating element. Why?

Answer:
a) Joule's law of heating: The heat (H) produced in a resistor is directly proportional to the square of current (I²), directly proportional to the resistance (R), and directly proportional to the time (t) of current flow.
Formula: H = I²Rt.
b) Reasons for using Nichrome:
1. Possesses a very high resistivity.
2. Has a very high melting point.
3. Does not easily get oxidized even at high red-hot temperatures.

26. Give the salient features of "Modern atomic theory".

Answer:
1. An atom is no longer indivisible; it consists 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 changed into atoms of another element (Artificial transmutation).
5. Atom is the smallest particle that takes part in a chemical reaction, and its mass can be converted into energy (E = mc²).

27. In what way do hygroscopic substances differ from deliquescent substances?

Hygroscopic Substances	Deliquescent Substances
Absorb moisture from air without dissolving.	Absorb moisture from air and dissolve in it completely.
Do not change their physical state.	Lose crystalline state and turn into liquid solutions.
Amorphous solids or liquids.	Crystalline solids.
E.g., Conc. H₂SO₄, Silica gel, Quicklime.	E.g., Solid NaOH, KOH, FeCl₃.

28. i) Give an account on vascular bundle of dicot stem. ii) Write the dental formula of rabbit.

Answer:
i) Vascular bundle of Dicot stem:
• Arranged in the form of a ring around the pith (Eustele).
• Conjoint: Xylem and phloem lie on the same radius.
• Collateral: Phloem lies towards the exterior and xylem towards the interior.
• Open: Cambium strip is present between xylem and phloem (capable of secondary growth).
• Endarch: Protoxylem points towards the centre and metaxylem towards the periphery.
ii) Dental formula of rabbit: (I 2/1, C 0/0, PM 3/2, M 3/3) or 2033 / 1023.

29. i) What causes the opening and closing of guard cells of stomata during transpiration? ii) What is the importance of valves in the heart?

Answer:
i) Stomatal movement: Caused by changes in the turgor pressure of the guard cells. In light, endosmosis occurs; guard cells become turgid, bowing outward and opening the stoma. In darkness, exosmosis occurs; guard cells become flaccid and the stoma closes.
ii) Importance of heart valves: Regulate unidirectional flow of blood through cardiac chambers and strictly prevent backflow of blood into preceding chambers.

30. i) What are the structures involved in the protection of brain? ii) What are allosomes?

Answer:
i) Protective structures:
1. Cranium: Bony skull protecting the brain from external mechanical injuries.
2. Meninges: Three protective membranes — Dura mater, Arachnoid membrane, and Pia mater.
3. Cerebrospinal fluid (CSF): Cushions the brain against mechanical shocks and maintains intracranial pressure.
ii) Allosomes: Chromosomes responsible for determining the biological sex of an individual (e.g., X and Y chromosomes).

31. i) What are synthetic auxins? Give examples. ii) What is colostrum? How is milk production hormonally regulated?

Answer:
i) Synthetic auxins: Artificially synthesized chemical compounds having physiological properties similar to natural auxins.
Examples: 2, 4-D (2, 4-Dichlorophenoxyacetic acid), NAA (α-Naphthalene acetic acid), IBA (Indole-3-butyric acid).
ii) Colostrum & Hormonal regulation:
• Colostrum: The first nutrient-rich, yellowish milk secreted by mammary glands for 2 to 3 days post-childbirth; loaded with antibodies (IgA) providing natural passive immunity.
• Prolactin (anterior pituitary) stimulates the synthesis and secretion of milk.
• Oxytocin (posterior pituitary) stimulates the ejection/let-down of milk from the mammary alveoli.

32. [Compulsory] Calculate the % of each element in calcium carbonate (CaCO₃). (Atomic mass: C = 12, O = 16, Ca = 40).

Solution:
Molar mass of CaCO₃ = 40 + 12 + 3(16) = 40 + 12 + 48 = 100 g/mol
• % of Calcium (Ca) = (40 / 100) × 100 = 40%
• % of Carbon (C) = (12 / 100) × 100 = 12%
• % of Oxygen (O) = (48 / 100) × 100 = 48%

Part - IV • Answer all the questions: 3 × 7 = 21

33. (a) i) List any five properties of light. ii) Draw a ray diagram to show the image formed by a convex lens when the object is placed between F and 2F.

Answer:
i) Properties of light:
1. Light is an electromagnetic transverse wave and a form of energy.
2. Travels along a straight line in a homogeneous medium.
3. Propagates through vacuum without requiring any material medium.
4. Speed in vacuum or air is c = 3 × 10⁸ m/s.
5. In the visible spectrum, violet has the shortest wavelength and red has the longest wavelength.

ii) Image formation (Object between F and 2F):
• Position of Object: Between F₁ and 2F₁.
• Position of Image: Beyond 2F₂ on the opposite side.
• Nature & Size: Real, inverted, and magnified image.

(OR) 33. (b) i) Derive the ideal gas equation. ii) State Ohm's law.

Answer:
i) Ideal Gas Equation Derivation:
From Boyle's law: PV = Constant (at constant T, n)
From Charles's law: V / T = Constant (at constant P, n)
From Avogadro's law: V / n = Constant (at constant P, T)
Combining these three 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.
Substituting Universal Gas Constant R = N_A k_B (8.31 J mol⁻¹ K⁻¹), for 1 mole of gas:
PV = RT.

ii) Ohm's Law:
At constant temperature, the steady current (I) flowing through a conductor is directly proportional to the potential difference (V) between its ends (V = IR).

34. (a) i) What is Molar volume of a gas? ii) Write the different types of isotopes of oxygen and its percentage abundance. iii) State two conditions necessary for rusting of iron.

Answer:
i) Molar volume: The volume occupied by one mole of any gaseous substance at Standard Temperature and Pressure (STP — 273 K and 1 atm); it is equal to 22.4 litres (or 22,400 ml).
ii) Isotopes of oxygen and their abundance:
• ₈O¹⁶ — 99.757%
• ₈O¹⁷ — 0.038%
• ₈O¹⁸ — 0.205%
iii) Conditions for rusting:
1. Presence of oxygen (air).
2. Presence of water (moisture).

(OR) 34. (b) i) Write notes on: 1) Saturated solution 2) Unsaturated solution. ii) What is an aqueous and non-aqueous solution? Give an example.

Answer:
i) Types of solutions:
• Saturated solution: A solution in which no more solute can be dissolved in a given amount of solvent at a specified temperature (e.g., 36 g of NaCl in 100 g of water at 25°C).
• Unsaturated solution: A solution containing less solute than that required for saturation at that temperature; more solute can be dissolved in it (e.g., 10 g or 20 g of NaCl in 100 g of water at 25°C).
ii) Aqueous vs Non-aqueous solutions:
• Aqueous solution: A solution in which water acts as the solvent (e.g., Common salt dissolved in water).
• Non-aqueous solution: A solution in which any liquid other than water acts as the solvent (e.g., Sulphur dissolved in carbon disulphide, CS₂).

35. (a) i) How are arteries and veins structurally different from one another? ii) Who discovered Rh factor? Why was it named so?

Answer:
i) Structural differences:

Arteries	Veins
Thick, elastic, and muscular walls.	Thin, non-elastic walls.
Lumen is narrow.	Lumen is wide.
Internal valves are absent.	Internal semilunar valves are present.
Distribute blood under high pressure away from heart.	Collect blood under low pressure towards the heart.

ii) Rh factor: Discovered by Landsteiner and Wiener in 1940 in the blood of Rhesus monkey.

(OR) 35. (b) i) With a neat labelled diagram explain the structure of a neuron. ii) Define triple fusion.

Answer:
i) Structure of a Neuron:
1. Cyton (Soma / Cell Body): Broad central part containing a prominent spherical nucleus, neuroplasm, and protein-rich Nissl's granules.
2. Dendrites: Highly branched, fine cytoplasmic processes extending from the cyton that receive impulses and carry them towards the cell body.
3. Axon: A long, single, unbranched cylinder conducting impulses away from the cell body. Wrapped in an insulating lipid myelin sheath provided by Schwann cells; interrupted at intervals by Nodes of Ranvier. Terminates into synaptic knobs that release neurotransmitters across synapses.

ii) Triple fusion: The process in angiosperms where one haploid male gamete (n) fuses with the diploid secondary nucleus (2n) in the central cell of the embryo sac to form the triploid Primary Endosperm Nucleus (3n).