CBSE Class 10 Science Important Questions 2027 — Chapter-Wise

CBSE Class 10 Science is 80 marks of theory and 20 of internal assessment. Chemistry and Biology topics together are 50 of the 80 marks. Below are important questions from each chapter, all within the CBSE 2026-27 syllabus; topics that are now assessed only by your school are listed at the end.

Unit-Wise Marks (CBSE 2026-27)

The question paper is arranged by subject: Section A Biology (30 marks), Section B Chemistry (25) and Section C Physics (25).

Chemistry

Chemical Reactions and Equations

• Write balanced equations for (a) burning magnesium in air, (b) zinc with dilute hydrochloric acid, (c) heating ferrous sulphate crystals.
• What is a combination reaction? Give two examples with balanced equations.
• Distinguish between exothermic and endothermic reactions with examples.
• What happens when lead nitrate is heated? Write the balanced equation and name the type of reaction.
• Identify the substance oxidised and the substance reduced in a given redox reaction.

Acids, Bases and Salts

• What is the pH scale? Why is the pH of the mouth important for tooth decay?
• How is bleaching powder prepared? Give two uses.
• Write the chemical formula and one use each of baking soda, washing soda and plaster of Paris.
• What happens when an acid reacts with a metal carbonate? Write the equation and the test for the gas produced.

Metals and Non-metals

• Show the formation of NaCl and MgO by the transfer of electrons. Why do ionic compounds have high melting points?
• Arrange given metals in the reactivity series and predict whether a displacement reaction will occur.
• What is corrosion? Describe two ways of preventing the rusting of iron.
• Explain the steps in extracting a metal of medium reactivity from its sulphide ore.

Carbon and its Compounds

• What is a homologous series? Give three of its features and write the first five alkanes.
• Write the IUPAC names of CH₃CHO, CH₃COOH, CH₃CH₂OH and CH₃COCH₃.
• Distinguish between saturated and unsaturated hydrocarbons. How would you test for unsaturation?
• What happens when ethanol reacts with sodium? Write the equation.
• Explain the cleansing action of soap with a diagram of a micelle.

Biology

Life Processes

• Draw a labelled diagram of the human heart and describe the flow of blood through it.
• State the role of hydrochloric acid, bile, villi and pancreatic enzymes in digestion.
• Draw a labelled diagram of a nephron and explain how urine is formed.
• Distinguish between (a) arteries and veins, (b) aerobic and anaerobic respiration.
• Draw a stoma and explain how it opens and closes. What is transpiration and why does it matter?

Control and Coordination

• Draw a labelled neuron and give the functions of the dendrite, axon and nerve ending.
• What is a reflex arc? Explain a reflex action with a diagram.
• Name three plant hormones and state the function of each.
• State the functions of the cerebrum, cerebellum and medulla.

How do Organisms Reproduce?

• Draw the longitudinal section of a flower and explain pollination and fertilisation.
• Describe two methods of asexual reproduction with examples.
• What are the common methods of family planning? Why is it important for reproductive health?

Heredity

• Explain Mendel's monohybrid cross with a Punnett square and give the phenotypic and genotypic ratios.
• How is the sex of a child determined in humans? Explain with a diagram.

Physics

Electricity

• State Ohm's law. Draw the V–I graph for a metallic conductor. What does its slope represent?
• Resistors of 2 Ω, 3 Ω and 6 Ω are connected in parallel across a 12 V battery. Find the equivalent resistance and the current drawn.
• Derive the equivalent resistance of resistors connected in series.
• A 1000 W heater is used for 2 hours a day. Find the cost of electricity for 30 days at ₹5 per unit.
• What is resistivity? On what factors does the resistance of a conductor depend?
• State Joule's law of heating and give two applications.

Light and the Human Eye

• Draw ray diagrams for a concave mirror with the object (a) at infinity, (b) between C and F, (c) at F.
• A concave mirror forms a real image three times the size of an object placed 10 cm from it. Find its focal length.
• Define the power of a lens and one dioptre. A lens has power −2.5 D; find its focal length and type.
• Why does light bend when it passes from one medium into another? State Snell's law.
• Explain myopia and hypermetropia and how each is corrected, with ray diagrams.
• Why does the sky look blue? Explain using scattering of light.

Magnetic Effects of Electric Current

• Draw the magnetic field lines around a straight current-carrying conductor and a solenoid.
• State Fleming's left-hand rule and use it to find the direction of the force on a conductor.
• Distinguish between AC and DC. What is an advantage of AC over DC?
• Explain the role of the fuse and earthing in domestic electric circuits.

Our Environment

• What is a food chain? Why do food chains usually have only three or four trophic levels?
• How is ozone formed in the upper atmosphere, and why is its depletion a concern?
• Distinguish between biodegradable and non-biodegradable substances with examples.

Assessed Only by Your School in 2026-27

CBSE's 2026-27 syllabus keeps these topics but assesses them only through school-based (formative) assessment, not in the Board exam: Periodic Classification of Elements, Evolution, and the electric motor, electromagnetic induction and the generator. Sources of Energy is no longer part of the Class 10 Science syllabus.

Answer-Writing Tips

1. Chemical equations: always balance them, add state symbols (s, l, g, aq) and write conditions above the arrow.
2. Physics numericals: Given → To find → Formula → Substitution → Answer with units.
3. Ray diagrams: use a ruler, label every point (F, C, P, O, I) and show arrows on the rays.
4. Biology diagrams: draw them large and neat in pencil and label all the main parts.
5. Differences: use a table with 4–5 points rather than a paragraph.

Unit marks, section marks and topic coverage follow CBSE's Class 10 Science syllabus and sample paper for 2026-27. Complete NCERT before using this list for revision.