CBSE Class 10 Science Question Paper 2024 (Set 1

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CBSE Class 10 Science Question Paper 2024 PDF (Set 1 - 31/5/1) is available for download here. CBSE conducted the Science exam on March 2, 2024, from 10:30 AM to 1:30 PM. The total marks for the theory paper are 80. The question paper contains 20% MCQ-based questions, 40% competency-based questions, and 40% short and long answer type questions. As per the students, the Science exam was moderate in difficulty level.

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CBSE Class 10 Science Question Paper 2024 (Set 1 - 31/5/1) with Answer Key

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CBSE Science Question Paper (Set 1 – 31/5/1) 2024 Solution

Question	Answer	Detailed Solution
1. To balance the following chemical equation, the values of the coefficients x, y, and z must be respectively: xZn(NO₃)₂ → yZnO + zNO₂ + O₂ (A) 4, 2, 2 (B) 4, 4, 2 (C) 2, 2, 4 (D) 2, 4, 2	(C) 2, 2, 4	The balanced chemical equation is: 2Zn(NO₃)₂ → 2ZnO + 4NO₂ + O₂. Conservation of atoms is maintained by ensuring equal numbers of each element on both sides of the equation.
2. Which of the following is a redox reaction, but not a combination reaction? (A) C + O₂ → CO₂ (B) 2H₂ + O₂ → 2H₂O (C) 2Mg + O₂ → 2MgO (D) Fe₂O₃ + 3CO → 2Fe + 3CO₂	(D) Fe₂O₃ + 3CO → 2Fe + 3CO₂	This reaction involves reduction (Fe₂O₃ to Fe) and oxidation (CO to CO₂). However, it forms multiple products, so it is not a combination reaction.
3. The salt present in tooth enamel is: (A) Calcium phosphate (B) Magnesium phosphate (C) Sodium phosphate (D) Aluminium phosphate	(A) Calcium phosphate	Tooth enamel is made of hydroxyapatite, a crystalline form of calcium phosphate. This provides hardness and durability to teeth.
4. An aqueous solution of sodium chloride is prepared in distilled water. The pH of this solution is: (A) 6 (B) 8 (C) 7 (D) 3	(C) 7	NaCl is a neutral salt formed from a strong acid (HCl) and a strong base (NaOH). Its aqueous solution has a neutral pH of 7.
5. A metal ‘X’ is used in the thermite process. When ‘X’ is heated with oxygen, it gives an oxide ‘Y’, which is amphoteric in nature. ‘X’ and ‘Y’ respectively are: (A) Mn, MnO₂ (B) Al, Al₂O₃ (C) Fe, Fe₂O₃ (D) Mg, MgO	(B) Al, Al₂O₃	Aluminum reacts with oxygen to form aluminum oxide (Al₂O₃), which is amphoteric (reacts with acids and bases).
6. The process in which transport of soluble products of photosynthesis takes place in plants is known as: (A) Transpiration (B) Evaporation (C) Conduction (D) Translocation	(D) Translocation	Translocation occurs in the phloem tissue, moving sugars from source (leaves) to sink (roots or storage organs).
7. The correct sequence of events when someone’s hand touches a hot object unconsciously: (A) Receptors in skin → Motor neuron → Relay neuron → Sensory neuron → Effector muscle in arm (B) Receptors in skin → Relay neuron → Sensory neuron → Motor neuron → Effector muscle in arm (C) Receptors in skin → Sensory neuron → Relay neuron → Motor neuron → Effector muscle in arm (D) Receptors in skin → Sensory neuron → Effector muscle in arm → Motor neuron → Relay neuron	(C) Receptors in skin → Sensory neuron → Relay neuron → Motor neuron → Effector muscle in arm	The reflex arc involves sensory neurons carrying signals to the spinal cord, relay neurons processing the response, and motor neurons activating muscles.
8. The sense organ in which olfactory receptors are present is: (A) Nose (B) Skin (C) Tongue (D) Inner ear	(A) Nose	Olfactory receptors in the nose detect volatile chemicals, sending signals to the brain for smell perception.
9. The incorrect statement about placenta is: (A) It is a disc embedded in the uterine wall. (B) It contains villi on the embryo’s side of the tissue. (C) It has a very small surface area for glucose and oxygen to pass from mother to the embryo. (D) The embryo gets nutrition from the mother’s blood through it.	(C) It has a very small surface area for glucose and oxygen to pass from mother to the embryo.	The placenta has a large surface area with villi to maximize the exchange of nutrients and gases.
10. Select from the following the conditions responsible for the rapid spread of bread mould on a slice of bread: (i) Formation of large number of spores (ii) Presence of moisture and nutrients in bread (iii) Low temperature (iv) Presence of hyphae (A) (i) and (ii) (B) (ii) and (iv) (C) (ii) and (iii) (D) (iii) and (iv)	(A) (i) and (ii)	Bread mould spreads rapidly due to spore formation and the presence of moisture and nutrients in bread.
11. How will the image formed by a convex lens be affected, if the upper half of the lens is wrapped with a black paper? (A) The size of the image formed will be one-half of the size of the image due to the complete lens. (B) The image of the upper half of the object will not be formed. (C) The brightness of the image will reduce. (D) The lower half of the inverted image will not be formed.	(C) The brightness of the image will reduce.	Wrapping the upper half of the lens blocks part of the incoming light, reducing the brightness of the image. However, the image size and shape remain unchanged.
12. The phenomena of light involved in the formation of a rainbow are: (A) Refraction, reflection, and dispersion (B) Refraction, dispersion, and internal reflection (C) Reflection, dispersion, and internal reflection (D) Refraction, dispersion, scattering, and total internal reflection	(B) Refraction, dispersion, and internal reflection	The formation of a rainbow involves refraction (light bending when entering a water droplet), dispersion (splitting into colors), and internal reflection (light reflecting inside the droplet before exiting).
13. The color of light for which the refractive index of glass is minimum is: (A) Red (B) Yellow (C) Green (D) Violet	(A) Red	Red light has the longest wavelength among visible light and undergoes the least bending. Thus, the refractive index of glass is minimum for red light.
14. The current-carrying device which produces a magnetic field similar to that of a bar magnet is: (A) A straight conductor (B) A circular loop (C) A solenoid (D) A circular coil	(C) A solenoid	A solenoid is a cylindrical coil of wire that generates a magnetic field resembling that of a bar magnet, with distinct north and south poles when current flows through it.
15. A uniform magnetic field exists in the plane of paper. In this field, an electron (e^-) and a positron (p⁺) enter as shown. The electron and positron experience forces: (A) Both pointing into the plane of the paper (B) Both pointing out of the plane of the paper (C) Pointing into the plane of the paper and out of the plane of the paper respectively (D) Pointing out of the plane of the paper and into the plane of the paper respectively	(A) Both pointing into the plane of the paper	The direction of the magnetic force is determined using the right-hand rule. For both particles, the forces point into the plane of the paper due to their opposite charges and motion.
16. Which one of the following is not a natural ecosystem? (A) Pond ecosystem (B) Grassland ecosystem (C) Forest ecosystem (D) Cropland ecosystem	(D) Cropland ecosystem	Cropland ecosystems are artificial, created and maintained by human activity, unlike natural ecosystems like ponds, grasslands, and forests.
17. Assertion (A): Some vegetable oils are healthy. Reason (R): Vegetable oils generally have long unsaturated carbon chains. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true.	(A) Both A and R are true, and R is the correct explanation of A.	Vegetable oils contain unsaturated fatty acids, which reduce bad cholesterol (LDL) and improve heart health. Their unsaturated nature explains their health benefits.
18. Assertion (A): Sex of the children will be determined by what they inherit from their mother. Reason (R): Women have XX sex chromosomes. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true.	(D) A is false, but R is true.	The father's chromosome determines the sex of the child, as men carry XY chromosomes and women carry XX chromosomes. The mother always contributes an X chromosome.
19. Assertion (A): Electrons move from lower potential to higher potential in a conductor. Reason (R): A dry cell maintains electric potential difference across the ends of a conductor. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true.	(B) Both A and R are true, but R is not the correct explanation of A.	Electrons flow from lower to higher potential due to their negative charge. A dry cell creates the necessary potential difference but does not explain electron flow.
20. Assertion (A): Ozone layer protects the surface of the Earth from harmful UV radiations. Reason (R): Chlorofluorocarbons (CFCs) are responsible for the depletion of the ozone layer. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true.	(A) Both A and R are true, and R is the correct explanation of A.	The ozone layer absorbs UV radiation, protecting life on Earth. CFCs release chlorine radicals that destroy ozone, depleting its protective effect.
21. (a) Copper powder is taken in a china dish and heated over a burner. Name the product formed and state its color. Write the chemical equation for the reaction involved.	Black copper(II) oxide (CuO)	Upon heating, copper reacts with oxygen to form black copper(II) oxide (CuO): 2Cu + O₂ → 2CuO The reaction shows copper's oxidation to CuO, which is black in color.
OR 21.(b) Write the chemical equation for the chemical reaction which occurs when aqueous solutions of barium chloride and sodium sulfate react together. Write the symbols of the ions present in the compound precipitated in the reaction.	BaCl₂ + Na₂SO₄ → BaSO₄ ↓ + 2NaCl	The reaction between barium chloride and sodium sulfate forms insoluble barium sulfate (BaSO₄) as a white precipitate. The ions in BaSO₄ are Ba²⁺ and SO₄^2-.
22. The melting and boiling points of carbon compounds are generally low, and they are largely non-conductors of electricity. State two conclusions based on these two properties.	Covalent bonding and lack of free ions/electrons	1. Low melting and boiling points indicate weak intermolecular forces in carbon compounds due to covalent bonding. 2. Non-conductivity implies the absence of free ions or electrons, as carbon compounds do not ionize in solutions.
23. (a) Sometimes, while running, athletes suffer from muscle cramps. Why? How is respiration in this case different from aerobic respiration?	Anaerobic respiration; lactic acid production	Muscle cramps occur due to the accumulation of lactic acid in muscles. During vigorous exercise, oxygen supply is insufficient, and anaerobic respiration takes place instead of aerobic respiration: Glucose → Lactic acid + Energy In aerobic respiration, glucose is fully oxidized to CO₂ and H₂O.
OR 23.(b)Write the other name given to lymph. State its two functions.	Tissue fluid	Lymph is also called tissue fluid. Its functions include: 1. Transporting nutrients, oxygen, and hormones to cells. 2. Removing waste products and aiding in immune response by carrying lymphocytes.
24. Some unicellular organisms such as Plasmodium and Leishmania differ in the manner in which they reproduce. Name and explain the reproductive process taking place in them.	Plasmodium: Multiple fission; Leishmania: Binary fission	- Plasmodium reproduces by multiple fission, where the nucleus divides repeatedly, and the cytoplasm splits to form many daughter cells. - Leishmania reproduces by binary fission, where the organism splits into two identical daughter cells. Due to its elongated body, binary fission occurs longitudinally.
25. The heat produced at a point due to the concentration of sunlight by a convex lens burns a paper. (a) Explain why it happens. (b) Name the term (in the context of the lens used) given to the point at which the paper starts burning. What does the bright spot formed on the paper represent?	Focus; Image of the Sun	(a) A convex lens converges sunlight to a single point (focus), concentrating energy and producing sufficient heat to burn the paper. (b) The bright spot is the image of the Sun formed at the focal point of the lens.
26. An electric source can supply a charge of 500 coulombs. If the current drawn by a device is 25 mA, find the time in which the electric source will be discharged completely.	20,000 seconds (or ~5.56 hours)	Given: Q = 500 C, I = 25 mA = 25 × 10^-3 A Time (t) = Q/I = 500 / (25 × 10^-3) = 20,000 seconds. Converting seconds to hours: 20,000 / 3600 ≈ 5.56 hours. The electric source will take approximately 20,000 seconds to discharge completely.
27. Study the experimental setup shown in the diagram and write the chemical equation for the reaction involved. Name and define the type of reaction. List two other metals which can be used in place of iron to show the same type of reaction with copper sulfate solution.	Fe + CuSO₄ → FeSO₄ + Cu Displacement reaction Zinc and Magnesium	In the reaction, iron displaces copper from copper sulfate solution, forming iron sulfate and copper metal: Fe + CuSO₄ → FeSO₄ + Cu This is a displacement reaction where a more reactive metal (iron) displaces a less reactive metal (copper). Other metals like zinc and magnesium can also displace copper in this reaction.
28. Name the ore of mercury and state the form in which it is found in nature. Write the chemical equations along with the conditions required for the reactions involved in the extraction of mercury from its ore.	Ore: Cinnabar (HgS) Found as: Mercury(II) sulfide Reactions: 2HgS + 3O₂ → 2HgO + 2SO₂ 2HgO → 2Hg + O₂	Mercury is extracted from its ore cinnabar (HgS): 1. Roasting: HgS is heated in oxygen to form mercury(II) oxide and sulfur dioxide. 2HgS + 3O₂ → 2HgO + 2SO₂ 2. Reduction: Mercury(II) oxide is further heated to produce mercury metal and oxygen. 2HgO → 2Hg + O₂ Mercury is found in nature as a sulfide compound (HgS).
29. Taking the example of any two animal hormones along with their gland of secretion, explain how these hormones help in: (i) Growth and development (ii) Regulating metabolism in the body	Hormones: Growth hormone and thyroxine Growth: Stimulates body growth Metabolism: Controls metabolic rate	(i) Growth and Development: - Growth Hormone (secreted by the pituitary gland): Promotes cell division, bone growth, and muscle development. Its deficiency causes dwarfism, and excess causes gigantism. (ii) Regulating Metabolism: - Thyroxine (secreted by the thyroid gland): Regulates the basal metabolic rate (BMR), ensuring proper metabolism of carbohydrates, proteins, and fats. Deficiency causes hypothyroidism, while excess causes hyperthyroidism.
30. Mendel crossed pure tall pea plants (TT) with pure short pea plants (tt) and obtained F₁ progeny. When the plants of F₁ progeny were self-pollinated, plants of F₂ progeny were obtained. (a) What did the plants of F₁ progeny look like? Give their gene combination. (b) Why could the gene for shortness not be expressed in plants of F₁ progeny? (c) Write the ratio of the plants obtained in F₂ progeny and state the conclusion drawn from this experiment.	(a) Tall, Tt (b) Masked by dominant allele (c) Phenotypic ratio: 3:1; Genotypic ratio: 1:2:1	(a) All F₁ plants were tall with gene combination Tt (heterozygous). (b) The gene for shortness (t) is recessive and is masked by the dominant allele (T) in F₁ progeny. (c) In the F₂ generation: - Phenotypic ratio: Tall : Short = 3:1 - Genotypic ratio: TT : Tt : tt = 1:2:1 Conclusion: Traits are controlled by alleles, and dominant alleles mask the expression of recessive alleles in heterozygous conditions.
31. (a) Study the diagram given below and answer the following questions: (i) Name the defect of vision depicted in the diagram and state the part of the eye responsible for this condition. (ii) List two causes of this defect. (iii) Name the type of lens used to correct this defect and state its role.	(i) Hypermetropia; Eye lens (ii) Short eyeball, low converging power (iii) Convex lens; Converges light	(i) The defect is hypermetropia (far-sightedness). The eye lens fails to focus light properly on the retina. (ii) Causes: - The eyeball is too short, reducing the distance between the lens and retina. - The eye lens loses its converging power. (iii) A convex lens is used to correct hypermetropia. It converges incoming light rays before they enter the eye, enabling the image to form on the retina.
OR 31. (b) What is dispersion of white light? State its cause. Draw a diagram to show dispersion of a beam of white light by a glass prism.	Splitting of light; Different wavelengths refract differently	Dispersion is the phenomenon where white light splits into its constituent colors (VIBGYOR) when passing through a prism. Cause: Different wavelengths of light refract by different amounts due to varying speeds in the prism medium. Diagram: The diagram shows white light splitting into seven colors as it passes through a prism.
32. (a) What happens when a bundle of wires of soft iron is placed inside a solenoid carrying a steady current? Name the device obtained. Why is it called so?	Electromagnet	When a bundle of soft iron wires is placed inside a solenoid, the magnetic field of the solenoid magnetizes the iron, creating a strong temporary magnet. Device: Electromagnet. Reason: It is called an electromagnet because its magnetism is induced by the electric current in the solenoid.
OR 32. (b) Draw the magnetic field lines inside a current-carrying solenoid. What does this pattern of magnetic field lines indicate?	Uniform magnetic field	The magnetic field lines inside a solenoid are parallel and equidistant, indicating a uniform magnetic field. Outside the solenoid, the lines spread out, resembling the magnetic field of a bar magnet.
33. Differentiate between food chain and food web. In a food chain consisting of deer, grass, and tiger, if the population of deer decreases, what will happen to the population of organisms belonging to the first and third trophic levels?	Food chain: Single path Food web: Multiple paths Grass increases, tiger decreases	Difference: - Food Chain: Linear sequence of energy transfer. - Food Web: Network of interconnected food chains. Effect of Deer Decrease: - Grass (first trophic level) increases due to reduced grazing. - Tigers (third trophic level) decrease due to reduced food availability.
34. (a) A few crystals of ferrous sulfate are heated in a test tube. Tiny droplets of water appear, and the crystals change color. Explain the observations and write the chemical reaction involved.	Loss of water of crystallization FeSO₄·7H₂O → FeSO₄	On heating, ferrous sulfate (FeSO₄·7H₂O) loses water of crystallization, forming anhydrous ferrous sulfate (FeSO₄), which is white. Further heating decomposes it into ferric oxide (Fe₂O₃), sulfur dioxide (SO₂), and sulfur trioxide (SO₃). Reaction: 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃.
OR 34. (b) An acid ‘X’ present in tamarind when mixed with ‘Y’ produces a mixture ‘Z’. ‘Z’ on addition to dough when heated makes cakes soft and spongy. ‘Y’ is prepared from common salt and helps in faster cooking. (i) Write the common names of ‘X’, ‘Y’, and ‘Z’, and the chemical formula of ‘Y’. (ii) How is ‘Y’ prepared, and how does it help in making cakes soft and spongy? Illustrate with a chemical equation. (iii) Write the name and chemical formula of a mild base other than ‘Y’ used as an antacid.	(i) X: Tartaric acid; Y: Baking soda (NaHCO₃); Z: Baking powder (ii) Baking soda releases CO₂, making cakes soft (iii) Milk of magnesia; Mg(OH)₂	(i) The common names are: - ‘X’: Tartaric acid (acid in tamarind). - ‘Y’: Baking soda (NaHCO₃). - ‘Z’: Baking powder (a mixture of baking soda and tartaric acid). (ii) Preparation and Function of Baking Soda: Baking soda (NaHCO₃) is prepared by reacting sodium chloride (NaCl) with ammonia (NH₃), carbon dioxide (CO₂), and water (H₂O): NaCl + NH₃ + CO₂ + H₂O → NaHCO₃ + NH₄Cl. - Baking soda decomposes when heated, releasing carbon dioxide gas (CO₂): 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂. The release of CO₂ causes the dough to rise, making cakes soft and spongy. (iii) A mild base used as an antacid is milk of magnesia, with the chemical formula Mg(OH)₂. It neutralizes stomach acid and relieves acidity.
35. (a) Design an experiment to demonstrate that carbon dioxide is essential for photosynthesis. Write the observation and conclusion of the experiment.	Potassium hydroxide setup CO₂ absence → No starch	Experiment: - Place a de-starched potted plant in sunlight. - Cover one leaf with a bell jar containing potassium hydroxide (KOH) to absorb CO₂. - Test the leaves for starch using iodine solution. Observation: The leaf inside the jar (no CO₂) does not turn blue-black, indicating no starch formation. The other leaf does. Conclusion: CO₂ is essential for photosynthesis.
OR 35. (b) (i) In the experimental setup shown above in diagram (I), atmospheric air is being passed into lime water with a syringe, while in diagram (II), air is being exhaled into lime water. The time taken for the lime water to turn milky in both the test tubes is different. Give the reason.	Exhaled air has more CO₂	Lime water turns milky due to the reaction of carbon dioxide (CO₂) with calcium hydroxide (lime water): Ca(OH)₂ + CO₂ → CaCO₃ ↓ + H₂O. Exhaled air contains a higher concentration of CO₂ (~4%) compared to atmospheric air (~0.03%), so lime water in diagram (II) turns milky faster.
(ii) Draw the diagram of an open stomatal pore and label (I) Guard cells, and (II) Chloroplast on it. Mention two functions performed by stomata.	Gas exchange and transpiration	Functions of Stomata: 1. Gas exchange: Allows CO₂ entry for photosynthesis and O₂ release. 2. Transpiration: Facilitates water vapor loss, aiding in cooling and nutrient transport. Diagram: The diagram should depict an open stomatal pore with labeled guard cells and chloroplasts.
36. (a) (i) The potential difference across a circuit component is reduced to one-third, while its resistance remains constant. What happens to the current flowing through it? Name and state the law used to answer this question. (ii) Draw a schematic diagram of a circuit with a 6V battery, a 5Ω resistor, a 10Ω resistor, a 15Ω resistor, and a key connected in series. Calculate the current through the circuit and the potential difference across the 10Ω resistor.	(i) Current decreases to one-third (ii) Current: 0.2A; V across 10Ω: 2V	(i) From Ohm's Law: V = IR, if V becomes 1/3 and R is constant, then I becomes 1/3. Ohm's Law: The current flowing through a conductor is directly proportional to the voltage across it, provided the resistance remains constant. (ii) Total resistance: 5Ω + 10Ω + 15Ω = 30Ω. Current: I = V/R = 6V / 30Ω = 0.2A. Potential difference across 10Ω: V = IR = 0.2 × 10 = 2V. The schematic diagram includes the battery, resistors in series, and a key.
OR 36. (b) (i) Define 1 volt. (ii) A copper wire with a diameter of 0.2 mm and resistivity 1.6 × 10⁻⁸ Ωm is used to create a 14Ω resistor. What is the required length of the wire? How does resistance change if the diameter is doubled?	(i) 1V = 1J/C (ii) Length: 27.5m; New resistance: 3.5Ω	(i) 1 volt is the potential difference when 1 joule of work moves 1 coulomb of charge between two points. (ii) Resistance R = ρL/A, where A = πr² = 3.14 × (0.1 × 10⁻³)² = 3.14 × 10⁻⁸ m². Length: L = RA/ρ = (14 × 3.14 × 10⁻⁸) / (1.6 × 10⁻⁸) = 27.5m. When diameter doubles, area increases 4x; new resistance = 14/4 = 3.5Ω.
37. Carbon is a versatile element that forms the basis of all living organisms. Answer the following: (a) What are hydrocarbons? (b) List two properties by virtue of which carbon can form a large number of compounds. (c)(i) Write the formula of the functional group present in aldehydes and ketones. Write the chemical equation for the reaction between ethanoic acid and ethanol.	(a) Organic compounds composed of only carbon and hydrogen. (b) Properties: Catenation and Tetravalency. (c)(i) Aldehydes: –CHO, Ketones: C=O. Esterification: CH3COOH + C2H5OH → CH3COOC2H5 + H2O.	(a) Hydrocarbons form the backbone of organic chemistry with classifications like alkanes, alkenes, and alkynes. (b) Catenation allows carbon to form chains, and tetravalency lets it bond with multiple elements. (c)(i) Aldehydes have –CHO, ketones have C=O. Esterification produces esters, e.g., ethyl ethanoate.
OR 37.(c)(ii) What are structural isomers? Write the structures of two isomers of butane.	(c)(ii) Structural isomers have the same molecular formula but different arrangements. Examples: n-Butane and iso-Butane.	(c)(ii) Structural isomers differ in structure, e.g., n-Butane: CH3-CH2-CH2-CH3 and iso-Butane: (CH3)2CH-CH3.
38. Pollination is essential for reproduction in plants. Answer the following: (a) Write the difference between self-pollination and cross-pollination. (b) Name the flower part attracting insects for pollination. What happens to it post-fertilisation? (c)(i) Define fertilisation. State the fate of ovules and the ovary post-fertilisation.	(a) Self-pollination involves the same flower; cross-pollination involves different plants. (b) Petals attract insects; they wither post-fertilisation. (c)(i) Fertilisation: Fusion of gametes. Ovules → Seeds, Ovary → Fruit.	(a) Self-pollination ensures genetic similarity, while cross-pollination increases genetic diversity. (b) Petals lose function and fall off after fertilisation. (c)(i) Fertilisation leads to zygote formation. Ovules form seeds, ovaries turn into fruits aiding dispersal.
OR 38.(c)(ii) In a germinating seed, name future shoot and root parts. Mention cotyledon function.	(c)(ii) Plumule: Future shoot, Radicle: Future root. Cotyledons store and supply nutrients.	Plumule grows into the shoot, radicle forms roots. Cotyledons nourish the embryo during germination.
39. Reflection and mirrors are integral to optics. Answer the following: (a) Define the principal axis of a concave mirror. (b) A ray parallel to the axis passes through the focus 10 cm from the pole. Find the mirror's radius of curvature. (c)(i) An object is placed 10 cm from a convex mirror (f=15 cm). Find image position.	(a) Straight line through pole and center of curvature. (b) R = 20 cm. (c)(i) Image at 6 cm behind the mirror.	(a) The principal axis is the symmetry line of a concave mirror. (b) R = 2f = 2 × 10 = 20 cm. (c)(i) Mirror formula: 1/f = 1/v + 1/u gives v = 6 cm, virtual and diminished.
OR 39.(c)(ii) A mirror forms a virtual, erect, diminished image. Identify the mirror. Draw its ray diagram.	(c)(ii) Convex mirror.	Convex mirrors always produce virtual, erect, and diminished images useful for wide-field views.