CBSE Class 10 Important Questions of Science with Answers | Free PDFs for 2026-27

Preparation for the Science Board Exam becomes easier when students get access to good resources and follow a proper strategy. CBSE Class 10 Important Questions of Science PDFs are materials that help with better preparation and scoring well. 

These PDFs include questions that are mostly important and repetitive from the past few years. On this page, we discuss the importance of these PDFs and how to use them for better results. This will help you prepare for the next CBSE board exam 2026-27. 

Download CBSE Class 10 Science Chapter-wise PDF Download link

It’s a heavy burden to go through all the chapters to search for important questions and answers. Thus, we have arranged all the important questions of each chapter in one place by making PDFs. Tap the links to download Chapter-wise PDFs of CBSE Class 10 Important Questions in Science. 

Chapter 1: Chemical Reactions and Equations Important Questions

Chapter 2: Acids, Bases and Salts Important Questions

Chapter 3: Metals and Non-metals Important Questions

Chapter 4: Carbon and its Compounds Important Questions

Chapter 5: Life Processes Important Questions

Chapter 6: Control and Coordination Important Questions

Chapter 7: How do Organisms Reproduce? Important Questions

Chapter 8: Heredity Important Questions

Chapter 9: Light - Reflection and Refraction Important Questions

Chapter 10: The Human Eye and the Colourful World Important Questions

Chapter 1: Electricity Important Questions

Chapter 12: Magnetic Effects of Electric Current Important Questions

Chapter 13: Our Environment Important Questions

CBSE Class 10 Science  Board Exam Pattern

The newly released CBSE syllabus 2026-27 states that the General Science Theory Paper carries a total of 80 marks. It consists of a total of 27 questions, including MCQs, assertion-reasoning, VSA, SA, LA, and Case-Based or Source-Based Questions. 

The table below will help you understand the Board Exam pattern of Science.

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CBSE Class 10 Science Unit-Wise Weightage of Science

The CBSE Marking Scheme doesn’t provide Chapter-wise mark distribution. Instead, it divides the chapters into 5 different units and provides marks based on that. The table below shows the marks for every unit of the theory paper.

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CBSE Class 10 Science Important Topics of Every Chapter from Every Unit

Each unit covers 4 to 5 chapters from the NCERT science textbook. Below, we discuss the important topics of all chapters. The estimated marks section below is based on the analysis and observation of last year's question patterns.

Unit 1: Chemical Substances – Nature and Behaviour (Chemistry)

This unit carries 25 marks with 4 chapters. All the repetitive topics are included below.

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Unit 2: World of Living (Biology)

The Biology unit included in the syllabus consists of 4 chapters. This part carries a total of 25 in the question paper. The following are the important topics for this section.

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Unit 3 and 4: Natural Phenomena & Effects of Current (Physics)

The Physics part is important as it has 12 marks from the 4 chapters in the textbook. Below are the important topics that students should follow while practicing for the board exam.

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Unit 5: Natural Resources

The natural resources part of the syllabus includes only one chapter. The questions from this chapter come for 5 marks. It can be any MCQ, VSA, SA, or an LA.

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CBSE Class 10 Science  Important Questions With Solutions 2026-27

This section highlights a few CBSE Class 10 Science important questions with answers that are repeated in the Board Exams. These questions are chosen from Previous Years’ questions and answered according to the CBSE standard. 

1. Chemical Reactions and Equations

Q1. (Easy) What is a chemical equation?

Ans: A chemical equation is a symbolic representation of a chemical reaction using the formulae of reactants and products.

• Reactants are written on the left side
• Products are written on the right side. 

It shows the transformation of substances during a chemical reaction in a short and balanced form.

Q2. (Easy) Balance the equation: Fe + H₂O - Fe₃O₄ + H₂

Ans: Balanced equation is: 3Fe + 4H₂O - Fe₃O₄ + 4H₂

• First, iron atoms are balanced by putting 3 before Fe
• Then hydrogen and oxygen atoms are balanced using coefficients
• The final equation has an equal number of atoms on both sides

Q3. (Medium) What is oxidation and reduction? Give an example.

Ans: Oxidation is the process of addition of oxygen or removal of hydrogen and reduction is the process of removal of oxygen or addition of hydrogen

Example: CuO + H₂ - Cu + H₂O

• CuO is reduced to Cu (removal of oxygen)
• H₂ is oxidized to H₂O (addition of oxygen)

Q4. (HOTS) Why do silver articles turn black on exposure to air?

Ans: Silver articles turn black due to the formation of a layer of silver sulphide (Ag₂S). Silver reacts with sulfur compounds present in air. This is a slow oxidation reaction. The black coating reduces the shine of silver objects

2. Acids, Bases and Salts

Q1. (Easy) What happens when an acid reacts with a base?

Ans: When an acid reacts with a base, a neutralization reaction takes place.

• Acid + Base - Salt + Water
• This reaction releases heat energy
• The resulting solution becomes less acidic or less basic depending on quantities

Q2. (Medium) Why does dry HCl gas not change the color of dry litmus paper?

Ans: Dry HCl gas does not show acidic behavior because:

• Acids show properties only in aqueous solution
• HCl requires water to release H⁺ ions
• Without water, no ion formation occurs, so litmus remains unchanged

Q3. (Medium) What is the pH scale? Explain its importance.

Ans: The pH scale measures the acidity or basicity of a solution on a scale of 0 to 14.

• pH < 7 - acidic solution
• pH = 7 - neutral solution
• pH > 7 - basic solution
  It is important because it helps determine the strength of acids and bases in daily life, like soil, digestion, and water quality.

Q4. (HOTS) Why is toothpaste basic in nature?

Ans: Toothpaste is basic because it neutralizes acids produced by bacteria in the mouth. These acids can damage tooth enamel. Its basic nature helps prevent tooth decay and maintains oral hygiene

3. Metals and Non-metals

Q1. (Easy) Why are metals good conductors of electricity?

Ans: Metals are good conductors because they contain free electrons. These electrons move freely through the metal structure, and this movement allows electric current to pass easily.

Q2. (Medium) What is rusting of iron?

Ans: Rusting is the corrosion of iron when it reacts with oxygen and moisture. Iron forms hydrated iron oxide (Fe₂O₃·xH₂O). Rust appears as a reddish-brown layer. It weakens the metal over time

Q3. (Medium) Why are ionic compounds brittle?

Ans: Ionic compounds are brittle because:

• They have strong electrostatic forces between ions
• When force is applied, layers shift
• Similar charges come closer and repel each other, causing the compound to break

Q4. (HOTS) Why is sodium stored in kerosene?

Ans: Sodium is stored in kerosene because:

• It reacts violently with air and water
• It can catch fire spontaneously
• Kerosene prevents contact with air and moisture

4. Carbon and its Compounds

Q1. (Easy) What is catenation?

Ans: Catenation is the ability of carbon atoms to form long chains by bonding with other carbon atoms. This property is unique due to strong carbon-carbon bonds. It leads to the formation of large organic compounds

Q2. (Medium) Why does carbon form covalent bonds?

Ans: Carbon forms covalent bonds because:

• It has 4 valence electrons
• It cannot easily lose or gain electrons
• It shares electrons to achieve a stable configuration

Q3. (Medium) What is a functional group?

Ans: A functional group is an atom or group of atoms that determines the chemical properties of an organic compound. Examples: Alcohol group (-OH) and carboxylic acid group (-COOH)

Q4. (HOTS) Why are hydrocarbons used as fuels?

Ans: Hydrocarbons are used as fuels because:

• They burn easily in oxygen
• They release large amounts of heat energy
• They produce carbon dioxide and water as products

5. Life Processes

Q1. (Easy) What is nutrition?

Ans: Nutrition is the process by which organisms obtain food and use it for energy, growth, and repair. It provides essential nutrients and supports all life activities.

Q2. (Medium) What is the function of stomata?

Ans: Stomata are tiny pores on leaves that allow the exchange of gases like CO₂ and O₂. They also help in transpiration (loss of water vapor).

Q3. (Medium) Why is respiration important?

Ans: Respiration is important because:

• It releases energy from food
• This energy is used for growth, movement and repair
• It is a continuous process in living organisms

Q4. (HOTS) Why is double circulation important in humans?

Ans: Double circulation is important because it keeps oxygenated and deoxygenated blood separate. It ensures efficient oxygen supply to body cells and supports high energy demand in humans

6. Control and Coordination

Q1. (Easy) What is the function of neurons?

Ans: Neurons are nerve cells that:

• Transmit electrical impulses
• Carry messages between brain and body
• Help in coordination of body activities

Q2. (Medium) What is reflex action?

Ans: Reflex action is an automatic response to a stimulus without conscious thinking. It is controlled by the spinal cord, and it helps protect the body from harm.

Q3. (HOTS) Why do plants bend towards light?

Ans: Plants bend towards light due to phototropism:

• Auxin hormone moves to the shaded side
• Cells grow faster on the shaded side
• This causes bending towards light

7. How do Organisms Reproduce?

Q1. (Easy) What is reproduction?

Ans: Reproduction is the biological process by which organisms produce new individuals of the same species. It ensures continuity of life and helps maintain the population.

Q2. (Medium) What is binary fission?

Ans: Binary fission is a type of asexual reproduction in which one cell divides into two identical daughter cells. It occurs in unicellular organisms like Amoeba

Q3. (HOTS) Why is variation important in reproduction?

Ans: Variation is important because:

• It helps organisms adapt to environmental changes
• Increases chances of survival
• Prevents extinction of species

8. Heredity

Q1. (Easy) What is heredity?

Ans: Heredity is the transfer of traits from parents to offspring.

• It explains similarities between generations
• Controlled by genes

Q2. (Medium) What are genes?

Ans: Genes are units of heredity located on chromosomes. They control specific traits like eye color, height and are passed from parents to offspring

Q3. (HOTS) Why are offspring not identical to parents?

Ans: Offspring are not identical because:

• Genetic recombination occurs during reproduction
• Variation is introduced during gene inheritance
• The environment also influences traits

9. Light - Reflection and Refraction

Q1. (Easy) What is reflection of light?

Ans: Reflection is the bouncing back of light when it strikes a surface.

• It follows laws of reflection
• It helps us see objects

Q2. (Medium) State the laws of reflection.

Ans: Laws of reflection are:

• Angle of incidence = Angle of reflection
• Incident ray, reflected ray, and normal lie in the same plane

Q3. (HOTS) Why does a straw look bent in water?

Ans: This happens due to refraction:

• Light changes direction when moving from water to air
• This creates a shifted image
• Hence straw appears bent

10. Human Eye and Colourful World

Q1. (Easy) What is myopia?

Ans: Myopia is a defect of vision in which:

• Nearby objects are seen clearly
• Distant objects appear blurred
• It is corrected using concave lenses

Q2. (Medium) Why is the sky blue?

Ans: The sky appears blue due to scattering of light:

• Shorter wavelengths (blue light) scatter more
• This scattered light reaches our eyes

Q3. (HOTS) Why do stars twinkle?

Ans: Stars twinkle because:

• Their light passes through different atmospheric layers
• Refraction keeps changing
• This causes apparent fluctuation in brightness

11. Electricity

Q1. (Easy) What is electric current?

Ans: Electric current is the flow of electric charge through a conductor. It is measured in amperes and requires a potential difference

Q2. (Medium) State Ohm’s Law.

Ans:
Ohm’s Law states that:

• V ∝ I (at constant temperature)
• V = IR, where R is resistance

Q3. (HOTS) Why do electric wires heat up?

Ans: Electric wires heat up due to:

• Resistance offered to current
• Electrical energy converting into heat energy
• This is called the Joule heating effect

12. Magnetic Effects of Electric Current

Q1. (Easy) What is a magnetic field?

Ans: A magnetic field is the region around a magnet where magnetic force can be experienced.

• It has direction and strength
• Represented by field lines

Q2. (Medium) What is an electromagnet?

Ans: An electromagnet is a temporary magnet:

• Made by passing current through a coil
• Strength can be controlled
• Used in cranes and devices

Q3. (HOTS) Why is soft iron used in electromagnets?

Ans: Soft iron is used because:

• It gets magnetized easily
• It loses magnetism quickly when current stops
• Makes electromagnet efficient

13. Our Environment

Q1. (Easy) What is an ecosystem?

Ans: An ecosystem is a system where:

• Living organisms interact with each other
• And with their physical environment
• It includes biotic and abiotic components

Q2. (Medium) What is a food chain?

Ans: A food chain is a sequence showing:

• Transfer of energy from one organism to another
• Example: Grass - Deer - Lion

Q3. (HOTS) Why is energy flow unidirectional?

Ans: Energy flow is unidirectional because:

• Energy is lost as heat at each trophic level
• It cannot be recycled back
• Hence, it flows in one direction only

Best CBSE Class 10 Science  Important Questions Book?

The new Educart Science Question Banks and One Shot Question Banks provide access to more Class 10 Important Questions of Science. Practicing with these books before the final board exams has various benefits. Because these books have:

• Topic -wise notes: The Question Banks provide visually engaging topic-wise notes for all the topics from the Textbook. 
• Various worksheets: The One-Shot QBs have different one-hour pull-over unit-test worksheets for better preparation for every chapter. 
• All types of Questions: Both the QBs have various MCQs, VSA, SA, and LA with case-based subjective and objective questions. 
• Step-by-step solutions: All the topics and solutions are presented step by step. This makes the understanding process easier while studying the topics. 
• Based on the CBSE pattern: Both the books strictly follow the CBSE Syllabus and Pattern of the Board Exam 2027. 

How to Practice Science Important Questions for Boards Exam 2026-27

Scoring well in the Science board examination requires a good strategy. Therefore, while practicing CBSE Class 10 Important Questions of Science, students must have other materials. For example, worksheets, Sample papers, PYQs, etc. 

Students should follow a few points while preparing for the exam to score competitive marks in the Board Exam 2026-27. 

• Follow NCERT: Textbooks are the base of the Board Exam. Thus, go through every chapter before choosing other materials. 
• Use of Question Bank: After studying one chapter, use question banks to understand other questions and how they are answered there. 
• Exercise One-shot QB: Exercise with the One-shot QB’s worksheets after completing all the chapters. It will help with a better understanding of the paper. 
• PYQs and Sample papers: Practice PYQs and Sample Papers to understand the question pattern. If possible, complete a paper within 3 hours, like in exams.  
• Focus on necessary skills: Time management and answer writing are two important skills for board exams. They can be easily adopted while solving PYQs and sample papers.

Recommended Books for Stronger Preparation for Board Exam 2026-27

Order Educart’s latest released books and materials for all Class 12 subjects. Make your preparation stronger for the Board Exam 2026-27.

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Frequently Asked Questions (FAQs)

Q1. Which are the most important chapters in CBSE Class 10 Science for 2026–27?

Ans: All Units’ chapters carry high marks in the question papers, and that’s why students should prepare the complete syllabus.

Q2. Where can I download CBSE Class 10 Science Important Questions PDF for free?

Ans: Download Class 10 Important Questions of Science PDFs from this page. You can also explore Educart Free Study Materials for additional resources.

Q3. How can I prepare for the CBSE Class 10 Science Board Exam 2026–27?

Ans: Complete NCERT, practise chapter-wise important questions, and solve sample papers under timed conditions. Check the Class 10 Science Syllabus for more insight.

Q4. Are important questions enough to score well in the Science Board Exam?

Ans: Important questions support revision, but they are not enough alone. Study NCERT thoroughly and practise previous years' question papers, sample papers, and numerical problems.

Q5. Which book is best for CBSE Class 10 Science Important Questions 2026–27?

Ans: Educart Science Question Banks and One Shot Question Banks offer chapter-wise practice, different question types, and solutions. Explore the available options in the Educart Books section.