CBSE Class 10 · Science · board exam 2027
CBSE Class 10 Science Question Paper 2026
The board’s 2026 question paper, set 31/1/1 — all 39 questions as printed; 20 objective answers from the board’s own key; full model answers for 3 written questions, how the answer begins for 9 more. Each question names its chapter, where that chapter’s most-asked questions are.
Full marks 80 · Time 3 h
Section A · Objective questions (20)
Which structure in a leaf is mainly responsible for gaseous exchange ?
- (A) Xylem
- (B) Stomata ✓
- (C) Phloem
- (D) Cuticle
Answer (the board’s key): (B)
Identify the type of reproduction shown in the diagram given below :
- (A) Budding
- (B) Fragmentation
- (C) Spore Formation
- (D) Binary Fission ✓
Answer (the board’s key): (D)
Select the correct statement in the context of Spirogyra, Leishmania and Hydra :
- (A) All of them reproduce sexually.
- (B) They are unicellular.
- (C) They are multicellular organisms.
- (D) They reproduce asexually. ✓
Answer (the board’s key): (D)
Human brain has various parts or regions that help in different actions, responses and coordination. From the following, identify the part responsible for precision of voluntary actions :
- (A) Cerebrum
- (B) Cerebellum ✓
- (C) Medulla
- (D) Pons
Answer (the board’s key): (B)
Pancreatic juice is secreted by the pancreas which contains some specific enzymes that help in digestion of food. Select the correct option from the following :
- (A) Trypsin digests emulsified fat and lipase digests protein.
- (B) Trypsin digests protein and lipase digests emulsified fat. ✓
- (C) Both trypsin and lipase digest fat.
- (D) Trypsin digests protein and lipase digests carbohydrates.
Answer (the board’s key): (B)
Sex is determined by different factors in various species. However, in human beings, it is determined genetically. Which amongst the following option(s) is/are correct for human beings ? (i) Gamete carrying X chromosome from female parent. (ii) Gamete carrying X chromosome from male parent. (iii) Gamete carrying Y chromosome from male parent.
- (A) (ii) and (iii) ✓
- (B) (i) only
- (C) (i) and (iii)
- (D) (iii) only
Answer (the board’s key): (A)
Which of the following is not a 'biodegradable' group?
- (A) Vegetable peels, dead leaves, paper
- (B) Cow dung, leather bag, water
- (C) Polythene bag, rubber band, ball pen ✓
- (D) Paper, fruit, bones
Answer (the board’s key): (C)
Assertion (A) : Reflex actions do not involve thinking. Reason (R) : Most reflex actions are controlled by the spinal cord.
- (A) Both, Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). ✓
- (B) Both, Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false.
- (D) Assertion (A) is false, but Reason (R) is true.
Answer (the board’s key): (A)
Assertion (A) : In human beings, the respiratory pigment is haemoglobin present in red blood cells. Reason (R) : Haemoglobin has a very high affinity for carbon dioxide.
- (A) Both, Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- (B) Both, Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false. ✓
- (D) Assertion (A) is false, but Reason (R) is true.
Answer (the board’s key): (C)
(i) AgNO3 + NaCl -> NaNO3 + AgCl (ii) K2SO4 + BaCl2 -> BaSO4 + 2KCl Which of the following options clearly describes both the reactions ?
- (A) (i) is double displacement, (ii) is displacement reaction.
- (B) Both (i) and (ii) are displacement reactions and precipitation reactions.
- (C) Both (i) and (ii) are double displacement reactions and precipitation reactions. ✓
- (D) (i) is displacement, (ii) is double displacement reaction.
Answer (the board’s key): (C)
Which one of the following can be used as an acid-base indicator by a visually impaired (blind) student ?
- (A) Turmeric
- (B) Vanilla essence ✓
- (C) Methyl orange
- (D) Litmus
Answer (the board’s key): (B)
The gases evolved on heating lead (II) nitrate crystals are :
- (A) NO and O2
- (B) N2 and NO2
- (C) NO2 and H2
- (D) NO2 and O2 ✓
Answer (the board’s key): (D)
The formula of functional group for aldehyde is :
- (A) -COOH
- (B) -CHO ✓
- (C) -C=O
- (D) -OH
Answer (the board’s key): (B)
Which of the following is a poor conductor of electricity ?
- (A) Pb ✓
- (B) Cu
- (C) Ag
- (D) Al
Answer (the board’s key): (A)
The natural sources of oxalic acid, lactic acid and methanoic acid respectively are :
- (A) tomato, curd, ant-sting ✓
- (B) tomato, orange, nettle-sting
- (C) orange, milk, ant-sting
- (D) orange, sour milk, nettle-sting
Answer (the board’s key): (A)
When an element 'X' reacts with water, it starts floating. Identify the element 'X' :
- (A) Potassium
- (B) Calcium ✓
- (C) Sodium
- (D) Iron
Answer (the board’s key): (B)
Assertion (A) : Carbon shares its valence electrons with other atoms of carbon or with atoms of other elements. Reason (R) : The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining the noble gas configuration.
- (A) Both, Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). ✓
- (B) Both, Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false.
- (D) Assertion (A) is false, but Reason (R) is true.
Answer (the board’s key): (A)
A convex lens of focal length 15 cm forms a real image. If the size of the image is equal to the size of the object, then the position of the object and the position of the image will be respectively :
- (A) at - 15 cm and at - 15 cm from lens
- (B) at - 15 cm and at + 15 cm from lens
- (C) at - 30 cm and at + 30 cm from lens ✓
- (D) at - 30 cm and at - 30 cm from lens
Answer (the board’s key): (C)
When you look at an object very close to your eyes, the :
- (A) Ciliary muscles of your eye contract and the eye lens becomes thick. ✓
- (B) Ciliary muscles of your eye get relaxed and the eye lens becomes thick.
- (C) Ciliary muscles of your eye contract and the eye lens becomes thin.
- (D) Ciliary muscles of your eye get relaxed and the eye lens becomes thin.
Answer (the board’s key): (A)
Directions : For question number 32, two statements are given, one labelled as Assertion (A) and the other is labelled as Reason (R). Select the correct answer to this question from the codes (A), (B), (C) and (D) as given below : Assertion (A) : When rays of white light pass through a prism, on emerging they give spectrum of seven colours. Reason (R) : It is due to the scattering of light that red light bends minimum and violet light bends the maximum.
- (A) Both, Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- (B) Both, Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false. ✓
- (D) Assertion (A) is false, but Reason (R) is true.
Answer (the board’s key): (C)
Section B · Written questions (19)
What is the function of diaphragm in human respiratory system ? Where is it present in human body ?
(a) State two differences between the act of chewing food and salivation on sight of food. OR (b) State two differences between pollination and fertilization.
Draw a neat diagram to show germination of pollen on the female reproductive part of the flower. Name and label only the following parts : (a) The part that receives the pollen grain. (b) The structure that carries the male germ cell to reach the female germ cell.
Given below is a pyramid showing various trophic levels in an ecosystem : (a) From the organisms listed below, identify which one is to be placed at which trophic level ? Deer, Grass, Lion, Snake, Rabbit (b) Discuss the reason why primary consumers will have more energy as compared to secondary consumers ? (c) Why is the base of the pyramid broad ?
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Model answer · trophic levels, energy pyramid
- 1.(a) Grass – producers (first trophic level); deer and rabbit – primary consumers (herbivores); snake – secondary consumer; lion – tertiary (top) consumer.1 mark
- 2.(b) Only about 10% of the energy at one level passes to the next; the rest is lost as heat and used in life processes. So secondary consumers get much less energy than primary consumers.1 mark
- 3.(c) The base is broad because producers are the most numerous and have the most energy, which supports the fewer organisms at each higher level.1 mark
Marks split as in the board’s published marking scheme
Give differences between the following : (a) Nephron and neuron (b) Sensory nerve and motor nerve (c) Consumers and decomposers
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Model answer · Differences: nephron, nerves, consumers
- 1.(a) Nephron: the basic filtration unit (structural and functional unit) of the kidney; Neuron: the structural and functional unit of the nervous system. Nephron: filters nitrogenous wastes such as urea from the blood; Neuron: transmits information from one part of the body to another.1 mark
- 2.(b) Sensory nerve: carries impulses from the receptors to the CNS (brain and spinal cord); Motor nerve: carries impulses from the CNS (brain and spinal cord) to the effector organs such as muscles.1 mark
- 3.(c) Consumers: organisms that feed on producers and other consumers; Decomposers: organisms that break down dead organic matter into simpler inorganic substances. Consumers: transfer energy through the food chain; Decomposers: recycle nutrients back into the environment.1 mark
- In (b), write the direction of the impulse for both nerves: "from the receptors to the CNS" and "from the CNS ... to the effector organs".
- In (a), write "unit of the kidney" for nephron and "unit of the nervous system" for neuron, plus what each one does.
- Write each pair on one line, with the same feature compared on both sides.
Marks split as in the board’s published marking scheme
Mendel took garden pea plants with different characteristics, such as height to study the inheritance pattern of factors (genes). He crossed tall pea plant with short pea plant and obtained all the tall plants in the F1 generation. Answer the following questions : (a) Why only tall pea plants were observed in F1 progeny ? (b) By which method did Mendel obtain F2 progeny ? (c) (i) Write one difference between dominant and recessive trait. OR (c) (ii) Write two observations made by Mendel about F1 progeny.
Medha Ma’am
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Model answer · Mendel's monohybrid cross, dominance
- 1.(a) Only tall plants appeared in F1 because tallness is dominant over dwarfness: every F1 plant is Tt, and one copy of T is enough to make it tall.0.5 marks
- 2.(b) Mendel obtained the F2 progeny by self-pollinating the F1 tall plants.0.5 marks
- 3.(c)(i) A dominant trait appears in the F1 hybrid; a recessive trait stays hidden in F1 and appears only in F2 (when both copies are recessive, tt). OR (c)(ii) All F1 plants were tall — only one parental trait was seen, with no medium-height plants; and the dwarf trait, hidden in F1, reappeared in F2.1 mark
Marks split from a structure derived from past papers (checked twice); not CBSE’s official scheme
(a) Given below are certain situations. Analyse each and describe its possible impact : (i) A population of bacteria living in temperate waters whose temperature increased by global warming. (ii) The sperm encounters the egg when it reaches the oviduct in human females. (iii) Self pollination does not occur in a flower that contains only pistil. (iv) Egg does not get fertilised in a human female. (v) When the seed is placed under appropriate condition of water and air in the soil ? OR (b) Given below are certain situations. Analyse and describe what would happen when : (i) Spores are liberated from blob-like structures of the bread mould? (ii) Leaves of bryophyllum fall on wet soil ? (iii) A pollen from different species land on the stigma of totally unrelated species ? (iv) Copper-T is placed in the uterus of a human female ? (v) Spirogyra breaks into smaller fragments upon maturation ?
How the model answer begins
1. (a) (i) When global warming raises the temperature of the temperate waters, most of these bacteria would die, but the few variants resistant to heat would survive and grow further.
The full answer from Medha Ma’am →(a) What are amphoteric oxides? (b) Categorise the following based on their nature : ZnO, Na2O, CO2
How the model answer begins
1. (a) Amphoteric oxides are metal oxides which react with both acids as well as bases to produce salts and water. Aluminium oxide and zinc oxide are examples, because they show both acidic and basic behaviour.
The full answer from Medha Ma’am →(a) Name the substance oxidised and reduced in the following reaction : ZnO + C -> Zn + CO (b) Balance the following chemical reaction : Pb(NO3)2 + KI -> PbI2 + KNO3 (c) Give one example each of electrolytic decomposition and decomposition by sunlight.
(a) Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode. OR (b) Write the preparation of following compounds with balanced chemical equation : (i) Baking soda (ii) Bleaching powder (iii) Plaster of Paris
Read the following passage and answer the questions given below : Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like - Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals. (a) Why carbonate or sulphide ores are converted into oxides before extraction of metal from it? (b) Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide. (c) (i) How is copper obtained from its ore (Cu2S)? Give equations of the reactions. (ii) Why highly reactive metals cannot be obtained from their oxides by using carbon as a reducing agent? (iii) Why solder, an alloy of lead and tin, is used for welding of electrical wires?
How the model answer begins
1. Carbonate or sulphide ores are converted into oxides before extraction of metal because it is easier to obtain a metal from its oxide, as compared to its sulphides and carbonates. The sulphide ores are converted into…
The full answer from Medha Ma’am →(a) (i) Give reasons for the following : (I) Covalent compounds are poor conductor of electricity. (II) Soap does not form lather in hard water. (III) Carbon shows catenation but silicon does not. (ii) Write chemical equations for the following : (I) Oxidation of ethanol by acidified K2Cr2O7. (II) Hydrogenation of ethene. OR (b) Mohan heated ethanol with a compound 'X' in the presence of a few drops of conc. H2SO4 and observed a sweet smelling compound 'Y' is formed. When 'Y' is treated with sodium hydroxide it gives back ethanol and a compound 'Z'. (i) Identify 'X', 'Y' and 'Z'. (ii) Write the role of conc. H2SO4 in the reaction. (iii) Write the chemical equations involved and name the reactions.
How the model answer begins
1. (a) (i) (I) Covalent compounds are poor conductors of electricity because they do not give rise to charged particles or ions. In covalent bonds, electrons are shared between two atoms, not transferred, so no ions are…
The full answer from Medha Ma’am →The given figure shows image formation by a lens. Analyse the figure and answer the following questions : (a) What is the type of lens used for image formation in the given ray diagram ? (b) If the real image is formed at a distance of 30 cm from the lens and the size of image is twice the size of the object, then where was the object placed ?
How the model answer begins
1. (a) A convex lens — only a convex lens forms a real image, and here the image is also magnified.
The full answer from Medha Ma’am →(a) The resistance of a wire of 0.01 cm radius and 1.0 cm length is 7 Ω. Calculate its resistivity. OR (b) An electric heater is rated 220 V; 11 A. Calculate the power consumed if the heater is operated at 200 V.
A person is unable to read a book placed closer than 1 meter from his eyes. Identify the defect of vision in his eyes. Draw the ray diagrams to show the defect of vision and its correction.
How the model answer begins
1. The person is suffering from hypermetropia, which is also known as far-sightedness.
The full answer from Medha Ma’am →(a) Describe an activity to show that a current carrying conductor, placed in an external magnetic field experiences a force. (b) Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally towards the front wall from the back wall, is deflected by a strong magnetic field to your right side. Find the direction of the magnetic field.
How the model answer begins
1. (a) Take a small aluminium rod AB, about 5 cm long. Use two connecting wires to hang it horizontally from a stand. Place a strong horse-shoe magnet so that the rod lies between its two poles, with the north pole…
The full answer from Medha Ma’am →(a) The pattern of magnetic field due to a current carrying wire depends upon the shape made by that wire. Justify. (b) A current carrying straight wire AB is shown in the given diagram. Out of X, Y and Z on which point will the strength of magnetic field be maximum and why ?
How the model answer begins
1. (a) Around a straight current-carrying wire, the field lines are concentric circles centred on the wire, in a plane perpendicular to it; they get larger, and the field weaker, farther from the wire.
The full answer from Medha Ma’am →Read the following passage and answer the questions given below: Lenses can form different types of images depending on their focal length and the position of the object. A convex lens forms real, inverted or virtual, erect images while a concave lens always forms virtual and diminished images. The focal length determines the power of a lens. By convention, the focal length of a convex lens is positive while the focal length of a concave lens is negative. When lenses are placed in contact with each other, their total power is determined by the sum of the individual powers of the lenses. Ray diagrams help in showing how light converges or diverges through a lens to form images. (a) A convex lens of focal length 20 cm is used to form an image. If an object is placed at a distance of 40 cm from the lens, what will be the position and nature of the image? (b) With the help of a ray diagram, show the formation of image in the situation when the object is placed between the principal focus and the optical centre of a concave lens. (c) (i) In a lens combination, a convex lens of focal length 30 cm and a concave lens of focal length 15 cm are placed together in contact. Find the equivalent focal length and power of this combination. or (c) (ii) Two lenses are placed in contact. One is a concave lens of focal length 2 m and the other is a convex lens of focal length 1.5 m. What type of lens (convex or concave) will this combination behave as? Give reason.
How the model answer begins
1. (a) 1/v − 1/u = 1/f with u = −40 cm and f = +20 cm: 1/v = 1/20 − 1/40 = 1/40, so v = +40 cm — the image is 40 cm on the other side of the lens (at 2F₂).
The full answer from Medha Ma’am →(a) (i) On changing the length and area of cross-section of a conductor, the resistance of the conductor changes, but the resistivity does not change. Why? (ii) The conductors of electric toasters and electric irons are made of alloys rather than pure metals. Why? (iii) Define the SI unit of electric current. or (b) (i) How many bulbs of resistance 8 Ω each, connected in parallel, would draw a current of 2 A from a 4 V battery? (ii) Write the name of the device used for measuring electric current. How is it connected in a circuit? (iii) Write the statement of Joule's law of heating.
The same preparation, with Medha Ma’am — on your phone
Every question of every chapter with its model answer, practice questions in the board’s own shapes, 60 minutes of class a day, written answers marked, a test every Sunday and a WhatsApp report to parents.
Medha Ma’am is an AI teacher, not a live tutor. Every answer is checked twice; a person takes responsibility.