CBSE Class 10 Science Previous Year Questions with Solutions

If you have ever finished a chapter and wondered, “Okay, but how will this actually show up in the exam?”, previous-year questions are your answer. They show you which concepts the board loves to revisit, how questions are worded, and how much detail an answer needs to earn full marks.

In this article, we have put together 32 important questions and 3 case studies based on recurring CBSE Class 10 Science board-exam patterns. They cover Chemistry, Biology and Physics, and include conceptual questions, chemical equations, numericals, diagram-based concepts and application-based questions. Every question comes with a step-by-step solution, so you can see not just the answer but the reasoning behind it.

These questions are meant for students preparing for the CBSE Class 10 Science Board Examination 2027. One honest note before you begin: they are adapted practice questions built around recurring board-exam patterns, not word-for-word copies of any particular year’s paper.

Download the printable file (PDF) of 32 important questions and 3 case studies

How to get the most out of this article?
Cover the solution and try each question on your own first. Then compare your answer with ours, and make a note of where your steps or wording differed. That small habit is where most of the learning happens.

Table of Contents

CBSE Class 10 Science Exam Pattern 2026–27

Let us start with the big picture. According to the CBSE Class 10 Science syllabus for the 2026–27 session, the theory paper carries 80 marks and runs for three hours. Another 20 marks come from internal assessment.

Unit	Marks
Chemical Substances – Nature and Behaviour	25
World of Living	25
Natural Phenomena	12
Effects of Current	13
Natural Resources	5
Total (Theory)	80
Internal Assessment	20
Grand Total	100

The paper tests three things: what you know, how well you can apply it, and how you think when a question looks unfamiliar. That is why it helps to practise every format, including objective questions, assertion-reason questions, short-answer and long-answer questions, and case-based questions.

Important syllabus note: Some topics that appear in older Class 10 Science papers are not part of the 2026–27 year-end assessment. For example, Periodic Classification of Elements and Heredity and Evolution are designated for formative assessment. Before you use any older paper for revision, check it against the latest syllabus so you do not spend time on topics that will not be asked.

CBSE Class 10 Science Previous Year Questions with Solutions

Every question below follows the current syllabus. Take them one section at a time, and do not rush through the numericals. Writing out each step is exactly what the board rewards.

Section A: Chemistry Important Questions and Answers

We begin with Chemistry. In board answers, a correctly balanced equation and a clear reason usually go hand in hand, so practise both together.

Chapter 1: Chemical Reactions and Equations

Question 1. Balance the following chemical equation and identify the type of reaction:

Fe + H₂O → Fe₃O₄ + H₂

Solution:

The balanced chemical equation is:

3Fe + 4H₂O → Fe₃O₄ + 4H₂

This is a redox reaction because oxidation and reduction occur simultaneously.

Iron is oxidised as it combines with oxygen.
Hydrogen in water is reduced as it forms hydrogen gas.

Question 2. What happens when an aqueous solution of sodium sulphate is mixed with barium chloride solution? Write the balanced chemical equation and identify the reaction.

Solution:

When sodium sulphate solution is mixed with barium chloride solution, a white insoluble precipitate of barium sulphate is formed.

Balanced chemical equation:

Na₂SO₄ + BaCl₂ → BaSO₄ ↓ + 2NaCl

This is a double displacement reaction because the ions of the two compounds exchange places.

It is also a precipitation reaction because an insoluble solid, barium sulphate, is produced.

Question 3. Explain oxidation and reduction with the help of the following reaction:

CuO + H₂ → Cu + H₂O

Solution:

In this reaction:

Copper oxide loses oxygen to form copper. Therefore, CuO is reduced.
Hydrogen gains oxygen to form water. Therefore, H₂ is oxidised.

Hence, this is a redox reaction because oxidation and reduction take place simultaneously.

Hydrogen acts as the reducing agent, while copper oxide acts as the oxidising agent.

Chapter 2: Acids, Bases and Salts

Question 4. Why does dry hydrogen chloride gas not change the colour of dry blue litmus paper, while aqueous hydrochloric acid turns blue litmus red?

Solution:

Hydrogen chloride produces hydrogen ions only when dissolved in water.

In dry conditions, HCl does not release hydrogen ions, so it does not change the colour of dry blue litmus paper.

When HCl dissolves in water, it ionises:

HCl + H₂O → H₃O⁺ + Cl⁻

The hydronium ions make the solution acidic and turn blue litmus red.

Question 5. A student tests three solutions using pH paper and obtains the following readings:

Solution A: pH 2
Solution B: pH 7
Solution C: pH 11

Identify the acidic, neutral and basic solutions. Which solution has the highest concentration of hydrogen ions?

Solution:

Solution A (pH 2): Acidic
Solution B (pH 7): Neutral
Solution C (pH 11): Basic

Solution A has the highest hydrogen-ion concentration because a lower pH indicates a greater concentration of hydrogen ions.

Question 6. What happens when baking soda reacts with hydrochloric acid? Write the balanced chemical equation and name the gas released.

Solution:

Baking soda is sodium hydrogen carbonate (NaHCO₃). When it reacts with hydrochloric acid, sodium chloride, water and carbon dioxide are produced.

Balanced chemical equation:

NaHCO₃ + HCl → NaCl + H₂O + CO₂ ↑

The gas released is carbon dioxide.

It can be tested by passing it through limewater. Limewater turns milky due to the formation of calcium carbonate.

Chapter 3: Metals and Non-Metals

Question 7. Why does zinc displace copper from copper sulphate solution? Write the balanced chemical equation.

Solution:

Zinc is more reactive than copper. Therefore, it displaces copper from copper sulphate solution.

Balanced chemical equation:

Zn + CuSO₄ → ZnSO₄ + Cu

Observations:

The blue colour of copper sulphate solution gradually fades.
A reddish-brown deposit of copper forms on the zinc.

This is a displacement reaction.

Question 8. Explain why ionic compounds have high melting and boiling points.

Solution:

Ionic compounds consist of positively charged and negatively charged ions held together by strong electrostatic forces of attraction.

A large amount of heat energy is required to overcome these forces and separate the ions.

Therefore, ionic compounds generally have high melting and boiling points.

Question 9. Why is sodium stored in kerosene?

Solution:

Sodium is a highly reactive metal. It reacts vigorously with oxygen and moisture in the air and may catch fire.

It is stored under kerosene to prevent contact with air and water.

Chapter 4: Carbon and Its Compounds

Question 10. What is a homologous series? Write two characteristics of a homologous series.

Solution:

A homologous series is a group of organic compounds having the same functional group and general formula, in which successive members differ by a –CH₂– unit.

Characteristics:

All members have similar chemical properties because they contain the same functional group.
The molecular mass of successive members differs by 14 u.
Their physical properties, such as boiling point and melting point, show a gradual change.

Example: Methane (CH₄), ethane (C₂H₆) and propane (C₃H₈) belong to the alkane series.

Question 11. What happens when ethanol reacts with ethanoic acid in the presence of concentrated sulphuric acid? Write the chemical equation and name the reaction.

Solution:

Ethanol reacts with ethanoic acid in the presence of concentrated sulphuric acid to form an ester and water.

Chemical equation:

CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

The ester formed is ethyl ethanoate.

This reaction is called esterification. Esters generally have a pleasant fruity smell.

Question 12. Why does soap form less lather in hard water?

Solution:

Hard water contains calcium and magnesium salts.

When soap is added to hard water, it reacts with calcium and magnesium ions to form insoluble substances called scum.

As a result:

Soap is wasted in forming scum.
Less lather is produced.
Cleaning becomes less effective.

Detergents are generally more effective than ordinary soaps in hard water because they do not form insoluble precipitates with calcium and magnesium ions as readily.

Section B: Biology Important Questions and Answers

Biology answers score best when they are clear and well organised. Wherever a diagram helps, draw it neatly and label it properly.

Chapter 5: Life Processes

Question 13. Explain the process of photosynthesis. Write its balanced chemical equation.

Solution:

Photosynthesis is the process by which green plants prepare their food using carbon dioxide and water in the presence of sunlight and chlorophyll.

During this process:

Chlorophyll absorbs sunlight.
Light energy is converted into chemical energy.
Water molecules are split, releasing oxygen.
Carbon dioxide is reduced to form carbohydrates.

Balanced chemical equation:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Conditions: Sunlight and chlorophyll.

Question 14. Explain how digested food is absorbed in the small intestine.

Solution:

The small intestine is the main site of absorption of digested food.

Its inner lining contains numerous finger-like projections called villi.

The villi:

Increase the surface area for absorption.
Contain blood capillaries that absorb glucose and amino acids.
Contain lymph vessels called lacteals that absorb most digested fats.

The absorbed nutrients are transported to different parts of the body through the circulatory system.

Question 15. Differentiate between aerobic and anaerobic respiration.

Solution:

Aerobic Respiration	Anaerobic Respiration
Takes place in the presence of oxygen.	Takes place without oxygen.
Complete breakdown of glucose occurs.	Incomplete breakdown of glucose occurs.
Releases more energy.	Releases less energy.
Produces carbon dioxide and water.	May produce alcohol and carbon dioxide, or lactic acid.

Aerobic respiration occurs in most human cells under normal conditions. Anaerobic respiration in human muscles may occur during vigorous exercise when oxygen supply is insufficient.

Question 16. Explain the role of xylem and phloem in plants.

Solution:

Xylem and phloem are the two main conducting tissues in plants.

Xylem:

Transports water and minerals from roots to other parts of the plant.
Movement is mainly upward.
Also provides mechanical support.

Phloem:

Transports food prepared by leaves to other parts of the plant.
Food can move in both directions depending on the plant’s needs.
This movement is called translocation.

Question 17. Describe the role of the nephron in the formation of urine.

Solution:

A nephron is the structural and functional unit of the kidney.

Urine formation takes place through three major processes:

Filtration: Blood is filtered under pressure in the glomerulus.
Selective reabsorption: Useful substances such as glucose, amino acids, salts and much of the water are reabsorbed into the blood.
Tubular secretion: Certain additional wastes and excess ions are secreted into the tubule.

The remaining fluid forms urine, which passes into the collecting ducts and then towards the ureter.

Chapter 6: Control and Coordination

Question 18. What is a reflex action? Explain the reflex arc with an example.

Solution:

A reflex action is a quick, automatic and involuntary response to a stimulus.

Example: Pulling your hand away immediately after touching a hot object.

The pathway followed by nerve impulses during a reflex action is called a reflex arc.

The sequence is:

Stimulus → Receptor → Sensory Neuron → Spinal Cord → Motor Neuron → Effector

The spinal cord coordinates the immediate response, helping protect the body from injury.

Question 19. What are plant hormones? Explain the role of auxin in phototropism.

Solution:

Plant hormones are chemical substances that regulate growth and development in plants.

Auxin is a plant hormone that promotes cell elongation.

When light falls on one side of a plant shoot, auxin accumulates more on the shaded side. Cells on that side grow faster, causing the shoot to bend towards the light.

This growth response towards light is called positive phototropism.

Chapter 7: How Do Organisms Reproduce?

Question 20. Differentiate between binary fission and budding with one example each.

Solution:

Binary Fission	Budding
One parent organism divides into two daughter organisms.	A small outgrowth or bud develops on the parent organism.
The nucleus divides, followed by division of the cytoplasm.	The bud grows and eventually separates from the parent.
Example: Amoeba.	Example: Hydra or yeast.

Both are forms of asexual reproduction and generally involve a single parent.

Question 21. Explain the functions of the following parts of a flower: (a) Stamen (b) Pistil (c) Ovary (d) Ovule

Solution:

Stamen: The male reproductive part of a flower. It produces pollen grains.
Pistil: The female reproductive part of a flower. It consists of stigma, style and ovary.
Ovary: Contains ovules and develops into the fruit after fertilisation.
Ovule: Contains the female gamete and develops into a seed after fertilisation.

Question 22. Mention three methods of contraception and explain why contraception is important.

Solution:

Three methods of contraception are:

Barrier methods: Condoms prevent sperm from reaching the egg and also help reduce the risk of sexually transmitted infections.
Hormonal methods: Oral contraceptive pills prevent pregnancy by interfering with ovulation and other reproductive processes.
Intrauterine devices (IUDs): Devices such as copper-T are placed inside the uterus to prevent pregnancy.

Contraception helps prevent unwanted pregnancies, supports family planning and protects reproductive health. Condoms also help reduce the transmission of HIV and other sexually transmitted infections.

Section C: Physics Important Questions and Answers

Physics numericals reward a tidy, step-by-step approach. Write what is given, choose the formula, substitute carefully, and always finish with the correct unit. Watch your signs in the mirror and lens problems.

Chapter 8: Light – Reflection and Refraction

Question 23. An object is placed 30 cm in front of a concave mirror having a focal length of 15 cm. Calculate the position and nature of the image.

Solution:

Given:

Object distance, u = −30 cm
Focal length, f = −15 cm

Using the mirror formula:

1/f = 1/v + 1/u

Substituting the values:

1/(−15) = 1/v + 1/(−30)

1/v = −1/15 + 1/30

1/v = −1/30

Therefore:

v = −30 cm

The image is formed 30 cm in front of the mirror.

Magnification:

m = −v/u

m = −(−30)/(−30) = −1

Answer: The image is real, inverted and of the same size as the object.

Question 24. An object is placed 30 cm in front of a convex lens of focal length 20 cm. Calculate the image distance and magnification.

Solution:

Given:

Object distance, u = −30 cm
Focal length, f = +20 cm

Using the lens formula:

1/f = 1/v − 1/u

Substituting:

1/20 = 1/v − 1/(−30)

1/20 = 1/v + 1/30

1/v = 1/20 − 1/30

1/v = 1/60

Therefore:

v = +60 cm

Magnification:

m = v/u

m = 60/(−30) = −2

Answer: The image is formed 60 cm on the other side of the lens. It is real, inverted and twice the size of the object.

Question 25. What is myopia? Explain how it can be corrected.

Solution:

Myopia, or short-sightedness, is a defect of vision in which a person can see nearby objects clearly but cannot see distant objects clearly.

In a myopic eye, the image of a distant object forms in front of the retina instead of on the retina.

Correction: Myopia is corrected using a concave lens of suitable power. The concave lens diverges incoming light rays so that the eye lens forms the image on the retina.

Chapter 9: Electricity

Question 26. A current of 3 A flows through a resistor when a potential difference of 12 V is applied across it. Calculate the resistance.

Solution:

Given:

Potential difference, V = 12 V
Current, I = 3 A

According to Ohm’s law:

V = IR

Therefore:

R = V/I

R = 12/3

Answer: Resistance = 4 Ω

Question 27. Two resistors of 6 Ω and 3 Ω are connected in parallel across a 12 V battery. Calculate the equivalent resistance and total current.

Solution:

Given:

R₁ = 6 Ω, R₂ = 3 Ω

For a parallel combination:

1/R = 1/R₁ + 1/R₂

1/R = 1/6 + 1/3

1/R = 1/6 + 2/6

1/R = 3/6 = 1/2

Therefore:

R = 2 Ω

Using Ohm’s law:

I = V/R

I = 12/2

Answer: Equivalent resistance = 2 Ω; Total current = 6 A

Question 28. An electric heater rated at 1000 W is used for 2 hours. Calculate the electrical energy consumed in kWh and joules.

Solution:

Given:

Power = 1000 W = 1 kW, Time = 2 hours

Electrical energy consumed:

Energy = Power × Time

= 1 × 2

= 2 kWh

Since 1 kWh = 3.6 × 10⁶ J,

Energy = 2 × 3.6 × 10⁶

Answer: Electrical energy = 2 kWh = 7.2 × 10⁶ J

Chapter 10: Magnetic Effects of Electric Current

Question 29. State the right-hand thumb rule. What does it help us determine?

Solution:

The right-hand thumb rule helps determine the direction of the magnetic field around a straight current-carrying conductor.

According to the rule:

If a straight conductor is held in the right hand such that the thumb points in the direction of conventional current, the curled fingers indicate the direction of the magnetic field lines around the conductor.

The rule is useful for understanding the magnetic field produced by electric current.

Question 30. Why are household electrical appliances connected in parallel rather than in series?

Solution:

Household electrical appliances are connected in parallel for the following reasons:

Each appliance receives the same potential difference as the mains supply.
Each appliance can be switched on or off independently.
If one appliance stops working, the others continue to operate.
Different appliances can draw the current required for their operation.

Therefore, parallel connections are more suitable for domestic electrical wiring.

Section D: Natural Resources – Important Questions

Question 31. Differentiate between biodegradable and non-biodegradable substances. Give two examples of each.

Solution:

Biodegradable Substances	Non-Biodegradable Substances
Can be broken down by microorganisms into simpler substances.	Cannot be broken down easily by natural biological processes.
Usually do not remain in the environment for very long when properly decomposed.	May remain in the environment for a long time.
Examples: Vegetable peels and paper.	Examples: Plastic and glass.

Biodegradable waste can be managed through composting, while non-biodegradable waste should be reduced, reused and recycled wherever possible.

Question 32. What is ozone depletion? Why is the ozone layer important for living organisms?

Solution:

Ozone depletion refers to the thinning of the ozone layer in the stratosphere due to the action of ozone-depleting substances, such as chlorofluorocarbons (CFCs).

The ozone layer is important because it absorbs much of the harmful ultraviolet (UV) radiation from the Sun.

Excessive exposure to UV radiation can cause:

Skin cancer.
Eye damage, including cataracts.
Harm to plants and aquatic organisms.

Reducing the use and release of ozone-depleting substances helps protect the ozone layer.

Section E: Competency-Based and Case-Based Questions

CBSE increasingly asks you to apply what you know to everyday situations. These three case studies give you a feel for that style. Read the passage carefully, then answer each part.

Case Study 1: Electricity in a Household

A family uses a 1000 W electric heater and a 100 W bulb. Both appliances operate on a 220 V household supply. The appliances are connected in parallel.

Answer the following questions:

(a) Why are the appliances connected in parallel?

Answer: Parallel connection ensures that each appliance receives the same supply voltage and can operate independently.

(b) Calculate the current drawn by the 1000 W heater.

Solution:

P = VI

I = P/V

I = 1000/220

Answer: Approximately 4.55 A.

(c) Calculate the current drawn by the 100 W bulb.

Solution:

I = P/V

I = 100/220

Answer: Approximately 0.45 A.

(d) What is the total current drawn when both appliances operate simultaneously?

Total current = 4.55 + 0.45

Answer: Approximately 5 A.

Case Study 2: Digestion in Humans

A student learns that the human digestive system breaks down complex food substances into simpler substances that can be absorbed by the body. Different digestive organs and enzymes perform specific functions.

Answer the following questions:

(a) Where does the digestion of starch begin?

Answer: Digestion of starch begins in the mouth with the help of salivary amylase.

(b) Which organ produces bile?

Answer: The liver produces bile.

(c) What is the function of bile in digestion?

Answer: Bile helps emulsify fats into smaller droplets, increasing the surface area available for the action of digestive enzymes. It also helps neutralise acidic food entering the small intestine.

(d) Where does the maximum absorption of digested food take place?

Answer: The small intestine, which contains numerous villi for efficient absorption.

Case Study 3: Refraction Through a Lens

A student uses a convex lens to form the image of an object placed at different distances. The student observes that the image changes in size and position depending on the object’s distance from the lens.

Answer the following questions:

(a) What happens when an object is placed beyond 2F₁ of a convex lens?

Answer: A real, inverted and diminished image is formed between F₂ and 2F₂.

(b) What happens when the object is placed at 2F₁?

Answer: A real, inverted image of the same size is formed at 2F₂.

(c) What is the nature of the image when the object is placed between F₁ and the optical centre?

Answer: A virtual, erect and magnified image is formed on the same side of the lens as the object.

(d) Which type of lens is used as a magnifying glass?

Answer: A convex lens.

Important Formulas for CBSE Class 10 Science

Keep this table handy while you practise numericals, and try to revisit it a little every day. Formulas stick far better when you use them than when you only read them.

Topic	Formula
Ohm’s Law	V = IR
Electric Power	P = VI
Power in terms of resistance	P = I²R
Power in terms of voltage	P = V²/R
Electrical Energy	E = Pt
Resistance in Series	R = R₁ + R₂
Resistance in Parallel	1/R = 1/R₁ + 1/R₂
Mirror Formula	1/f = 1/v + 1/u
Lens Formula	1/f = 1/v − 1/u
Magnification (Mirror)	m = −v/u
Magnification (Lens)	m = v/u
Power of a Lens	P = 1/f (f in metres)

One last reminder: always use the correct sign convention when solving mirror and lens problems. It is the most common place where marks slip away.

Tips to Prepare for the CBSE Class 10 Science Board Examination

Solving previous-year questions is one of the smartest things you can do, but it works best alongside textbook revision and a real understanding of the concepts. Here is how to put it all together.

1. Start with the latest CBSE syllabus

Begin by reading through the official syllabus for your academic session. It saves you from spending precious hours on topics that will not appear in the year-end examination.

2. Practise previous-year question papers

Sit down with a complete paper from a previous year and solve it under timed conditions, as if it were the real exam. You will quickly get a feel for the format and discover which areas need more work.

3. Get comfortable with chemical reactions

Practise balancing equations until it feels natural, and learn to spot the type of reaction in front of you, whether it is combination, decomposition, displacement, double displacement, oxidation or reduction.

4. Keep revising biology diagrams

Draw the labelled diagrams of the human digestive system, respiratory system, nephron and flower again and again. Neat drawings with clear labels make your answers easier to read and easier to reward.

5. Solve physics numericals step by step

Write the given values, pick the correct formula, substitute the numbers and finish with the right unit. Following the same pattern every time keeps careless mistakes away.

6. Practise competency-based questions

CBSE questions often test how well you can apply a concept to a real-life situation. Case-based, reasoning and data-interpretation questions are great practice, so do not rely on memorisation alone. Building good effective study techniques such as self-testing and spaced revision will help you here.

7. Follow a regular revision routine

Set aside time every day for revising concepts, practising questions and correcting your mistakes, and keep coming back to the difficult topics. If you are not sure where to begin, our guide on how to create a study schedule and this walkthrough of a daily study routine for students can help you plan your week.

Frequently Asked Questions (FAQs)

1. Where can I download CBSE Class 10 Science previous-year question papers?

You can download them from the official CBSE website. Head to the CBSE Previous Years’ Question Papers page, then choose the examination year and subject you need.

2. How many years of previous-year questions should I practise?

Practising at least five years of available question papers is a useful target. Just remember to check the current syllabus and focus first on the questions that cover topics included in your examination.

3. Are previous-year questions repeated in CBSE Class 10 Science board exams?

Some concepts and question patterns can come back in a different form, but you should not expect the exact same question. Concentrate on understanding the concept so you can apply it to a new situation.

4. Which sections of Class 10 Science should students focus on?

Prepare Chemistry, Biology and Physics thoroughly, following the prescribed syllabus. Do not forget to practise questions from Natural Resources and from application-based topics too.

5. How can I score high marks in CBSE Class 10 Science?

Read the NCERT textbook carefully, revise key concepts, practise numericals, learn your chemical equations, draw labelled diagrams, and solve previous-year and sample question papers. When you write answers, keep them clear and use scientific terms accurately.

Final Words

Solving CBSE Class 10 Science previous-year questions is one of the most effective ways to get ready for the board examination. It helps you understand important concepts, sharpen your answer writing and get used to different types of questions.

So work through the questions in this article, revise your NCERT textbook, and attempt full CBSE papers under exam conditions. Most importantly, aim to understand the idea behind each answer rather than memorising the solution word for word.

Consistent practice and clear concepts will carry you into the exam hall with far more confidence. And on the days when motivation dips, these tips on staying motivated and boosting exam performance are worth a read. You have got this!

Official CBSE Resources for Class 10 Science

Bookmark these pages. They let you check the syllabus, try the current sample paper and download actual previous-year papers straight from the source.

The official CBSE archive includes Class 10 papers for 2026, 2025, 2024 and earlier examination years.