Important QuestionsClass 10 - Science

Class 10 · Science · Important Questions

Important Questions

The question shapes that recur most on CBSE boards — drawn from 10 years of papers, the official blueprint, and examiner-pattern analysis.
Master these patterns first.

These are important question patterns to prioritise — not predictions of the exact 2027 paper. Full preparation still matters.

Question stacks

Showing all important questions across all topics.

Topic:

Chemical Reactions & Equations

Must-crack4 Q - 11 marks2 competency QsChemistry

High-priority pattern stack for 2027 board revision. Includes 2 competency-style questions.

Section A1 mark

Which of the following is the correctly balanced equation for the formation of iron(III) oxide from iron and oxygen (Fe + O₂ → Fe₂O₃)?

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Section B2 marks

Identify the type of reaction for: 2KClO₃ → 2KCl + 3O₂. Write one more example of the same type.

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Section E4 marksCase-based

A steel gate near the sea starts developing brown flaky patches after a few months. (a) Name the process and the type of chemical reaction involved. (b) Suggest two preventive measures. (c) Explain in brief how painting helps.

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Section E4 marksCase-based

Priya performed two experiments in the lab:
Experiment 1: She added zinc granules to a solution of copper sulphate.
Experiment 2: She heated ferrous sulphate crystals in a dry test tube.
(a) Write the balanced chemical equation for each experiment.
(b) Name the type of reaction in each experiment.
(c) What colour change will Priya observe in Experiment 1? Why?

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Acids, Bases & Salts

Must-crack5 Q - 15 marks3 competency QsChemistry

High-priority pattern stack for 2027 board revision. Includes 3 competency-style questions.

Metals & Non-metals

High-ROI12 Q - 22 marks6 competency QsChemistry

High-value pattern stack for focused 2027 revision. Includes 6 competency-style questions.

Section A1 mark

Which metal is softest?

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Section A1 mark

How do non-metals generally react with water?

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Section A1 markAssertion–Reason

Assertion: Zinc will displace copper from copper sulphate solution. Reason: Zinc is above copper in the activity series.
Assertion: Zinc will displace copper from copper sulphate solution.
Reason: Zinc is above copper in the activity series.

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Section B2 marks

Name the main step used to extract iron from hematite in the blast furnace. Describe briefly.

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Section E4 marksCase-based

Rohan lives in a coastal town and notices that his iron bicycle rusts much faster than his cousin's bicycle in a dry inland town.
(i) Name the two substances that must be present for iron to rust. [1]
(ii) Why does Rohan's bicycle rust faster in the coastal town? [1]
(iii) Suggest two methods to prevent rusting of the bicycle and briefly explain why each method works. [2]

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Section A1 mark

Which of the following metals is the most reactive?

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Section B2 marks

Define corrosion and state two conditions necessary for the rusting of iron.

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Alloys are generally harder than their constituent metals.
Reason: Atoms of different sizes in an alloy distort the regular arrangement of the metal atoms and resist the movement of layers.

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Section C3 marks

Aluminium is placed high in the reactivity series. (a) Why can aluminium not be obtained by heating its oxide with carbon? (b) Name the process used to obtain aluminium from its oxide and state what happens at the cathode.

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Section E4 marksCase-based

Iron nails are dipped in a copper sulphate solution. After some time a reddish‑brown deposit is observed on the nails and the blue colour of the solution fades.
(a) Write the balanced chemical equation for the reaction.
(b) What type of reaction is this?
(c) Why does the colour of the solution change?

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Copper does not react with dilute hydrochloric acid.
Reason: Copper is placed below hydrogen in the reactivity series.

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Copper does not react with dilute hydrochloric acid.
Reason: Copper is placed below hydrogen in the reactivity series.

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Carbon & its Compounds

High-ROI6 Q - 15 marks3 competency QsChemistry

High-value pattern stack for focused 2027 revision. Includes 3 competency-style questions.

Section A1 mark

The bond formed between two carbon atoms in ethane (C₂H₆) is:

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Section C3 marks

Define a homologous series. State any two characteristics of a homologous series of alkanes.

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Section B2 marks

Give the IUPAC names of CH₃–CH₂–CH₂–OH and CH₃–CO–CH₃.

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Section E4 marksCase-based

A student observes that soap lathers less in hard water but a synthetic detergent lathers well. (a) Explain the reason. (b) Write one advantage of detergents over soaps and one environmental disadvantage.

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Section E4 marksCase-based

A chemistry teacher showed her students the molecular formulae of three organic compounds: CH₄, C₂H₆, C₃H₈.
(a) Do these compounds form a homologous series? Give reason.
(b) Write the general formula for this series.
(c) Write the IUPAC name and structural formula of C₃H₈.
(d) What is the molecular formula of the next member of this series?

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Members of a homologous series have similar chemical properties.
Reason: They have the same functional group.

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Life Processes

Must-crack10 Q - 25 marks4 competency QsBiology

High-priority pattern stack for 2027 board revision. Includes 4 competency-style questions.

Section A1 mark

In humans, the mode of nutrition is:

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Section C3 marks

Differentiate between aerobic and anaerobic respiration in any three points.

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Section D5 marks

Draw a labelled diagram of the human heart and explain the route of blood flow to show double circulation.

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Section A1 mark

Which organelle is known as the powerhouse of the cell?

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Section B2 marks

Write the balanced chemical equation for photosynthesis.

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Veins carry blood from the different organs back to the heart.
Reason: Veins have thick, elastic walls because the blood in them flows under high pressure.

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Section C3 marks

Draw a neat labelled diagram of a nephron and describe the process of ultrafiltration.

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Section E4 marksCase-based

In an experiment, a leaf on a plant was partially covered with black paper and the plant was kept in sunlight for several hours. The leaf was then tested with iodine solution.
(a) Which process was being investigated?
(b) What will be the result of the iodine test on the covered and uncovered parts of the leaf?
(c) What conclusion can be drawn from this experiment?

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: The small intestine is the main site of absorption of digested food.
Reason: The inner lining of the small intestine has villi which increase the surface area for absorption.

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Section E4 marksCase-based

A student performed an experiment to show that CO₂ is necessary for photosynthesis. A potted plant was kept in the dark for 48 hours, then a leaf was enclosed in a flask containing KOH.
(a) Why was the plant kept in the dark for 48 hours?
(b) What is the role of KOH in the experiment?
(c) After exposing the plant to sunlight, what result would be observed on testing the enclosed leaf with iodine?
(d) Write the balanced chemical equation for photosynthesis.

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How do Organisms Reproduce?

High-ROI3 Q - 8 marks1 competency QBiology

High-value pattern stack for focused 2027 revision. Includes 1 competency-style question.

Light – Reflection & Refraction

Must-crack6 Q - 15 marks3 competency QsPhysics

High-priority pattern stack for 2027 board revision. Includes 3 competency-style questions.

Section A1 mark

Which mirror is used by dentists to see an enlarged image of teeth?

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Section C3 marks

An object is placed at 30 cm in front of a convex lens of focal length 15 cm. Find the position and nature of the image formed.

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Section D5 marks

Draw a labelled ray diagram to show refraction of light when it passes from a denser medium (glass) to a rarer medium (air). Mark the angle of incidence, angle of refraction and normal. State Snell’s law.

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Section E4 marksCase-based

A student placed an object 30 cm in front of a convex lens of focal length 20 cm.
(a) Find the position of the image using the lens formula.
(b) What is the magnification?
(c) State the nature of the image (real/virtual, inverted/erect, magnified/diminished).
(d) If the object is moved to a position 15 cm from the lens, how does the image change?

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: When light travels from a denser to a rarer medium, it bends away from the normal.
Reason: The speed of light increases when it passes from a denser to a rarer medium.

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: A concave mirror always forms a real and inverted image.
Reason: When the object is placed between the pole and focus of a concave mirror, the image formed is virtual and erect.

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Human Eye & Colourful World

Good-to-do2 Q - 3 marksPhysics

Useful pattern stack for completing topic coverage.

Electricity

Must-crack6 Q - 21 marks3 competency QsPhysics

High-priority pattern stack for 2027 board revision. Includes 3 competency-style questions.

Section A1 mark

According to Ohm’s law, the V–I graph for a metallic conductor at constant temperature is:

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Section C3 marks

Three resistors of 2 Ω, 3 Ω and 6 Ω are connected in parallel. Find their equivalent resistance.

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Section D5 marks

An electric heater of power 1000 W is used for 5 hours every day for 30 days. Calculate (a) total electrical energy consumed in kWh, and (b) cost of using the heater at ₹7 per kWh.

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Section E4 marksCase-based

A student uses a thin wire as a fuse in the circuit. (a) Why is a fuse always connected in series? (b) On what principle does it work? (c) What will happen to the fuse wire if current exceeds the safe limit?

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Section E4 marksCase-based

Two resistors of 6 Ω and 12 Ω are connected in parallel across a 12 V battery.
(a) Calculate the equivalent resistance of the combination.
(b) Find the total current drawn from the battery.
(c) Find the current through each resistor.
(d) If the 6 Ω resistor is removed, what will be the new current from the battery?

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Section E4 marksCase-based

Three resistors of 2Ω, 3Ω, and 6Ω are connected in parallel across a 12V battery.
(a) Find the equivalent resistance.
(b) Find the total current drawn from the battery.
(c) Find the current through the 3Ω resistor.
(d) Find the power dissipated in the 6Ω resistor.

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Magnetic Effects of Electric Current

High-ROI2 Q - 4 marksPhysics

High-value pattern stack for focused 2027 revision.

Control and Coordination

High-ROI6 Q - 12 marks3 competency QsBiology

High-value pattern stack for focused 2027 revision. Includes 3 competency-style questions.

Section A1 mark

Which plant hormone is responsible for cell elongation in stem?

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Section B2 marks

What is a reflex action? Draw the pathway of a simple reflex arc.

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Section C3 marks

Name any three endocrine glands in human beings and write one function of each.

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Section E4 marksCase-based

Rohan accidentally touches a hot pan while cooking.
(a) What type of response is this? Name the pathway involved.
(b) Draw a flow chart showing the sequence of events in this response.
(c) Why is the response faster than a voluntary action?
(d) Name the part of the nervous system where the response is coordinated.

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Auxin promotes cell elongation on the shaded side of a plant shoot.
Reason: Auxin migrates away from light to the darker side.

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Section A1 markAssertion–Reason

Assertion–Reason: refer to assertion and reason below.
Assertion: Reflex actions are involuntary and extremely quick.
Reason: In reflex actions, the signal travels through the reflex arc via the spinal cord, not the brain.

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Heredity

Must-crack4 Q - 11 marks2 competency QsBiology

High-priority pattern stack for 2027 board revision. Includes 2 competency-style questions.

Our Environment

Good-to-do1 Q - 4 marks1 competency QGeneral

Useful pattern stack for completing topic coverage. Includes 1 competency-style question.