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Paper pattern

Objective · all 20 · 1 mark each · multiple choice and assertion-reason20

Very short answer · all 6 · 2 marks each · about 30 to 50 words12

Short answer · all 7 · 3 marks each · about 50 to 80 words21

Case-based · all 3 · 4 marks each · case-based, 1 + 1 + 2 marks12

Long answer · all 3 · 5 marks each · about 80 to 120 words, with diagram15

Board paper total80

CBSE Science (086) question paper design and sample paper, 2026-27: 39 questions, 80 marks, 3 hours, internal choice in about a third of the questions.

Mock paper

Make a full practice paper in the same shape as the exam, picked from our question bank. Write your answers on paper, timed, then check them against the sheets.

Likely questions

Written by us from your syllabus, not copied from any exam paper. Tap one to open its sheet.

2 marks · short answer

Before a magnesium ribbon is burnt in the laboratory, it is rubbed with sandpaper. Explain why, and name the white powder formed when it burns.Unit I Balance the equation and add state symbols: aluminium reacts with steam to give aluminium oxide and hydrogen, Al + H₂O → Al₂O₃ + H₂.Unit I Classify respiration as exothermic or endothermic. Give a reason, with its balanced equation.Unit I Identify the substance oxidised and the substance reduced in H₂S + Cl₂ → 2HCl + S. Give a reason for each.Unit I What is rancidity? Give two ways to prevent it.Unit I What are olfactory indicators? Name two.Unit II Sour curd left in a copper vessel tastes bad and may be harmful to eat. Explain why, naming the kind of substance in curd.Unit II In a circuit test, a bulb glows with dilute HCl but not with glucose solution, though both contain hydrogen. Explain why.Unit II A drop of a solution turns red litmus blue. Which of these could be its pH: 2, 6, 7 or 11? Give a reason.Unit II Gypsum and plaster of Paris are both forms of calcium sulphate. How do they differ in formula, and how is each changed into the other?Unit II Give reasons: (i) a frying pan has a metal body but a plastic or wooden handle; (ii) a steel plate dropped on the floor makes a ringing sound.Unit III In the school laboratory, sodium is kept in a bottle of kerosene, never in water or an open dish. Explain why.Unit III Can copper sulphate solution be stored in an iron vessel? Give a reason with an equation.Unit III Calcium oxide melts at 2850 K, but ice melts at 273 K. Why do ionic compounds such as calcium oxide have such high melting points?Unit III What is an alloy? Why is solder used to join electrical wires, while the wires themselves are made of pure copper?Unit III Why does carbon form covalent bonds and not ionic bonds?Unit IV Explain, with one example each, how catenation and tetravalency help carbon form so many compounds.Unit IV Write the names of CH₃CH₂Cl and CH₃CH₂CH₂CHO.Unit IV A bottle labelled alcohol may really hold vinegar. Describe one test, using a substance found in the kitchen, to check this, and give the result for each liquid.Unit IV Why does soap not work well in hard water?Unit IV What are stomata? Write two functions of stomata.Unit V Why is the small intestine of a herbivore longer than that of a carnivore?Unit V Why does the trachea not collapse when there is little air in it? Why do aquatic animals breathe faster than land animals?Unit V Write two differences between xylem and phloem.Unit V What is a synapse? How is a nerve impulse passed across it?Unit VI How is a reflex action different from walking?Unit VI How are the brain and the spinal cord protected in the human body?Unit VI Why is the use of iodised salt advised? Name the disease caused by a lack of iodine.Unit VI Why is DNA copying an essential part of reproduction?Unit VII Name one organism that reproduces by binary fission and one that reproduces by multiple fission. How are the two processes different?Unit VII Why are the testes located in the scrotum, outside the abdominal cavity?Unit VII What is the placenta? How does it help the developing embryo?Unit VII Why do offspring from sexual reproduction show more variation than offspring from asexual reproduction?Unit VIII What are dominant and recessive traits? Give one example of each from Mendel's experiments.Unit VIII What is a gene? Where are genes found in a cell?Unit VIII How is the sex of the young decided in some reptiles and in snails?Unit VIII Define the principal focus of a concave mirror. A concave mirror has a radius of curvature of 36 cm. What is its focal length?Unit IX Give two reasons why a convex mirror is used as the rear-view mirror of a scooter or a car.Unit IX The refractive index of water is 1.33 and that of kerosene is 1.44. In which of the two does light travel faster? Give a reason.Unit IX Define 1 dioptre. Find the power of a convex lens of focal length 40 cm.Unit IX Define the power of accommodation. How does the focal length of the eye lens change when you look up from your book at a far-off tree?Unit X What is presbyopia? State two reasons why it happens.Unit X Why do stars twinkle at night while planets shine steadily?Unit X What is the Tyndall effect? Give one example of it from daily life.Unit X Define 1 volt. How much work is done in moving a charge of 2 C between two points that have a potential difference of 12 V?Unit XI Why are copper and aluminium used for electric transmission lines, while nichrome is used in electric heaters?Unit XI Give two reasons why appliances in a house are connected in parallel and not in series.Unit XI Which uses more energy: a 200 W television used for 2 hours, or a 1500 W toaster used for 15 minutes? Show your working.Unit XI Why do two magnetic field lines never intersect? What does the closeness of field lines show?Unit XII State the right-hand thumb rule. A current flows upwards in a vertical wire: what is the direction of the field lines when seen from above?Unit XII List two ways of making the magnetic field of a current-carrying solenoid stronger.Unit XII Give two differences between direct current and alternating current. What is the frequency of AC in India?Unit XII What would happen to a forest if all the decomposers in it died? Give two reasons.Unit XIII What is a food web? How is it different from a food chain?Unit XIII If 20,000 J of energy is available at the producer level, how much energy will reach the secondary consumers? State the law you used.Unit XIII Write the two equations that show how ozone is formed in the upper atmosphere.Unit XIII

3 marks · short answer

What happens when an iron nail is dipped in copper sulphate solution for about 20 minutes? Write the equation and name the type of reaction.Unit I Name the form of energy that breaks the reactant in each case, and write the balanced equation: (i) limestone heated in a lime kiln, (ii) acidified water with an electric current passed through it, (iii) silver bromide on a photographic film exposed to light.Unit I Colourless solutions of sodium sulphate and barium chloride are mixed, and a white solid appears. Name the white solid, write the balanced equation with state symbols, and name two types of reaction it belongs to.Unit I Explain how tooth decay happens and how it can be prevented.Unit II What is the chlor-alkali process? Write the equation and give one use of each product.Unit II Write the balanced equations for: (i) zinc warmed with sodium hydroxide solution, (ii) sodium carbonate with dilute HCl, (iii) excess carbon dioxide passed through lime water.Unit II Zinc oxide reacts with both hydrochloric acid and sodium hydroxide solution to form a salt and water. What is such an oxide called? Name one more example, and write its equations with an acid and with a base.Unit III Show the formation of calcium chloride (CaCl₂) by the transfer of electrons, and name its cation and anion.Unit III Differentiate between roasting and calcination. Write one equation for each.Unit III CH₄, C₂H₆ and C₃H₈ belong to one series. What is such a series called? State three of its features, using these compounds.Unit IV What are addition and substitution reactions? Give one equation for each, with the condition needed.Unit IV Draw the structures of ethane, ethene and ethyne, and say which are saturated and which are unsaturated.Unit IV List the three events of photosynthesis. How do desert plants take in carbon dioxide without losing much water?Unit V With a flow chart, show how glucose is broken down in yeast, in muscle cells short of oxygen, and in mitochondria.Unit V How do plants get rid of their excretory products? Give three ways.Unit V Draw a flow chart of the reflex arc for pulling your hand away from a hot object. Why does this response not wait for the brain?Unit VI How is the folding of the leaves of the touch-me-not plant different from the bending of a shoot towards light? Name the hormone involved in the bending.Unit VI Draw the structure of a neuron and label the dendrite, cell body, axon and nerve ending. Show the direction in which the impulse travels.Unit VI What is vegetative propagation? Give two advantages and two examples of plants grown this way.Unit VII List the changes that take place in a flower after fertilisation.Unit VII Name two bacterial and two viral sexually transmitted infections. How can their spread be prevented?Unit VII A pure tall pea plant is crossed with a pure short pea plant. Show the F1 and F2 generations with a checkerboard, and write both F2 ratios.Unit VIII Explain how a gene controls the height of a pea plant.Unit VIII With a flow chart, show that the sex of a child is decided by the father.Unit VIII An object is placed 8 cm in front of a concave mirror of focal length 12 cm. Use the mirror formula to find the position of the image and its magnification, and state the nature of the image.Unit IX State the two laws of refraction. Draw a diagram to show the path of a ray of light through a rectangular glass slab, and mark the angle of incidence and the angle of emergence.Unit IX Draw a ray diagram to show the image formed by a concave lens when an object is placed between infinity and its optical centre. State the position, size and nature of the image.Unit IX Draw a labelled ray diagram to show the refraction of a ray of light through a triangular glass prism. Mark the angle of incidence, the angle of emergence and the angle of deviation.Unit X What is dispersion of white light? Why do the colours separate when white light passes through a prism? How can the colours be combined again into white light?Unit X Why does the clear sky appear blue? How would the sky look to an astronaut on the Moon, and why?Unit X A wire of length 2 m and area of cross-section 4 × 10⁻⁷ m² has a resistance of 5 Ω. Find the resistivity of its material. What would the resistance be if the length were doubled?Unit XI How will you connect three resistors of 6 Ω each to get an equivalent resistance of (a) 18 Ω, (b) 2 Ω and (c) 9 Ω? Draw a diagram for each.Unit XI State Joule's law of heating and give two of its applications. Calculate the heat produced when a current of 0.5 A flows through a 100 Ω resistor for 2 minutes.Unit XI What is a solenoid? Draw the pattern of magnetic field lines around a current-carrying solenoid and mark its north and south poles.Unit XII State Fleming's left-hand rule. A horizontal wire carries a current from west to east in a magnetic field that points vertically upwards. Find the direction of the force on the wire.Unit XII What is the function of an earth wire? Why is it necessary to earth appliances that have metal bodies?Unit XII Explain biological magnification with an example. Why are human beings often the most affected?Unit XIII Why are food chains usually limited to three or four trophic levels? Explain using the ten percent law.Unit XIII Give three ways in which your school can reduce the waste it sends to the dump, and say why each one helps.Unit XIII

5 marks · long answer

What is a combination reaction? Describe what happens when water is added to quicklime, write the equation, say whether it is exothermic or endothermic, and explain why whitewashed walls shine after a few days.Unit I Define oxidation and reduction. With equations, explain what happens when copper powder is heated in air and the product is then heated in hydrogen. Name the oxidising agent and the reducing agent.Unit I How are baking soda and washing soda prepared? Write the equations. Give two uses of each, and explain why baking powder makes a cake soft and spongy.Unit II Describe an activity to show that acids react with metal carbonates to give carbon dioxide. Draw the set-up and write the equations, including what happens when excess gas is passed.Unit II Explain the steps used to extract a metal from the middle of the reactivity series, with equations. Describe the electrolytic refining of copper with a labelled diagram.Unit III Describe an activity to show that both air and water are needed for rusting. Explain three ways of preventing rusting.Unit III With a labelled diagram, explain how soap micelles remove oily dirt from clothes. Why do people with hard water at home prefer detergents?Unit IV With equations, describe the reaction of ethanol with sodium and with hot concentrated sulphuric acid, and the reaction of ethanoic acid with ethanol and with sodium hydrogencarbonate.Unit IV Describe the process of digestion in human beings. Draw a labelled diagram of the human alimentary canal.Unit V Draw a sectional view of the human heart and label it. Describe double circulation and explain why it is needed in mammals.Unit V Draw a labelled diagram of the human brain. Describe the jobs of the forebrain, the medulla and the cerebellum.Unit VI What are hormones? Name four endocrine glands, the hormone each makes and one job of each. Explain the feedback mechanism with an example.Unit VI Draw a longitudinal section of a flower and label the stigma, style, ovary, anther and filament. Describe pollination and fertilisation in flowering plants.Unit VII Draw a labelled diagram of the human female reproductive system. Describe how the embryo is nourished in the mother's body, and what happens when the egg is not fertilised.Unit VII Describe Mendel's dihybrid cross between pea plants with round yellow seeds and plants with wrinkled green seeds. Draw the F2 checkerboard and state the conclusion.Unit VIII Describe Mendel's monohybrid cross using tall and short pea plants. Explain the terms dominant and recessive, and give the F2 ratios with a checkerboard.Unit VIII Draw ray diagrams to show the image formed by a concave mirror when the object is placed (i) at the centre of curvature, (ii) between the centre of curvature and the focus, and (iii) between the focus and the pole. State the position, size and nature of the image in each case, and give one use of case (iii).Unit IX (a) Write the lens formula and the formula for magnification by a lens, and say what each symbol stands for. (b) An object 5 cm tall is placed 20 cm from a convex lens of focal length 15 cm. Find the position, size and nature of the image. (c) Find the power of the lens.Unit IX (a) What is myopia? State two causes of it. (b) Draw ray diagrams to show a myopic eye and its correction. (c) The far point of a myopic person is 2 m. Find the nature and power of the lens needed.Unit X Draw a labelled diagram of the human eye. Explain how the eye focuses first on a book in your hand and then on a tree far away. What are the near point and the far point of a normal eye?Unit X State Ohm's law. Describe an activity to verify it, with a labelled circuit diagram. Draw the V-I graph you expect and say what its slope gives.Unit XI Derive the expression for the equivalent resistance of three resistors connected in parallel. Resistors of 2 Ω, 3 Ω and 6 Ω are joined in parallel to a 6 V battery: find the equivalent resistance and the total current.Unit XI Describe an activity to show that a current-carrying conductor experiences a force in a magnetic field. How does the force change when the current is reversed? State the rule that gives its direction.Unit XII Draw a schematic diagram of a domestic electric circuit. Explain short-circuiting and overloading, and how a fuse protects the circuit.Unit XII Define an ecosystem and describe its biotic and abiotic components. Explain the roles of producers, consumers and decomposers, with an example of each.Unit XIII Explain the flow of energy in an ecosystem using a food chain with four trophic levels. State the ten percent law and explain why the flow of energy is unidirectional.Unit XIII

4 marks · case-based (1 + 1 + 2)

Answer frames

How to lay out a long answer, with a write-up check. 76 frames so far.