Important Questions for Class 10 Science with Answers PDF

Important questions for class 10 science are chapter-wise exam-focused questions drawn from the CBSE 2026 NCERT syllabus. They cover VSA, short answer, long answer, case-based, and competency-based formats across all 13 chapters. Students use them to identify high-weightage topics, practise answer writing, and revise faster before board exams.

Class 10 science important questions on this page cover all 13 NCERT chapters for CBSE 2026. You get chapter-wise links, curated most important questions, extra questions with answers, marks-based sets, and case-based practice. Every question follows the current 2026 syllabus.

A student who has practised these class 10 science important questions knows which concept each question targets, how to open an answer, and how much detail each marks category needs. Most marks are lost on answer structure. A student who writes three lines for a 5-mark question loses marks even with accurate content. All questions and answers are available chapter by chapter below.

Key Takeaways

Introduction to Important Questions for Class 10 Science

CBSE board exams reward students who practise writing answers. A student who has read about photosynthesis and a student who has written a 3-mark answer on it perform very differently in the exam.

Chapter coverage and answer structure are two separate skills. This page builds both. The chapter-wise links below take you to full question banks. The curated sets on this page give you the highest-probability questions from each chapter in one place.

Use this alongside NCERT Solutions Class 10 Science for textbook-level accuracy and Sample Papers Class 10 Science for timed full-paper practice.

Most Important Questions Class 10 Science

These are the most important questions class 10 science students cannot afford to skip. Each one has appeared across multiple CBSE board cycles and tests the exact reasoning examiners look for.

Most Important Questions on Chemical Reactions and Life Processes

These two chapters together account for the largest share of 3-mark and 5-mark questions in CBSE 2026 papers.

Q1. Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Iron is more reactive than copper. It displaces copper from copper sulphate solution. The blue colour fades as iron sulphate forms and copper deposits on the nail.

Q2. What is photosynthesis? Write the chemical equation. Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to make glucose and release oxygen. Equation: 6CO2 + 6H2O → C6H12O6 + 6O2.

Q3. What is the role of the epiglottis in the human body? The epiglottis is a cartilage flap that covers the windpipe during swallowing. It stops food from entering the trachea. Without it, food would reach the lungs instead of the stomach.

Most Important Questions on Light, Electricity and Heredity

These three chapters produce the most diagram-based and derivation questions in CBSE 2026 board papers.

Q4. How does the human eye adjust to see objects at different distances? Ciliary muscles change the thickness of the eye lens. They contract for nearby objects, making the lens thicker. They relax for distant objects, making the lens thinner. This is called accommodation.

Q5. What happens to resistance when the length of a conductor doubles? Resistance is directly proportional to length. When length doubles, resistance doubles. This holds true only when material and cross-sectional area stay the same.

Q6. State Mendel's two laws of inheritance. The Law of Segregation says alleles separate during gamete formation. The Law of Independent Assortment says alleles for different traits are inherited independently.

Q7. What is the magnetic field due to a current-carrying straight conductor? A straight conductor carrying current produces a magnetic field in concentric circles around it. The right-hand thumb rule gives the direction: thumb points in current direction, curled fingers show field direction.

Q8. How does binary fission differ from multiple fission? In binary fission, one organism splits into two. In multiple fission, the nucleus divides multiple times and produces many daughter cells at once. Amoeba uses binary fission; Plasmodium uses multiple fission.

Q9. Why is sustainable management of natural resources necessary? Natural resources are limited. Overuse depletes them and destroys ecosystems. Sustainable management ensures present needs are met without reducing future generations' access.

Q10. Distinguish between renewable and non-renewable energy sources with examples. Renewable sources replenish naturally: solar energy and wind energy. Non-renewable sources deplete over time: coal, petroleum, and natural gas. Once non-renewable sources are exhausted, they cannot be recovered.

Extra Questions for Class 10 Science with Answers

Science extra questions class 10 go one level deeper than standard revision. These questions test application and reasoning. Students targeting 90+ marks should practise these after completing the chapter-wise sets.

Extra Questions on Chemical Reactions and Physical Changes

These extra questions for class 10 science test whether students can distinguish between reaction types and change categories, two areas where marks are commonly lost.

Q1. A student mixes two colourless solutions and sees a yellow precipitate form. What type of reaction is this? This is a double displacement reaction. When two ionic solutions react and one product is insoluble, it settles as a precipitate. The yellow colour suggests a sulphide or sulphur-containing product.

Q2. Is dissolving sugar in water a physical or chemical change? Dissolving sugar is a physical change. No new substance forms. Sugar molecules separate and disperse in water but their chemical composition stays unchanged.

Extra Questions on Biology and Physics Application

Q3. Why do some organisms reproduce asexually even though sexual reproduction produces more variation? Asexual reproduction is faster and needs only one parent. In stable environments, existing traits already suit survival well. Producing variation is less important than reproducing quickly.

Q4. A convex lens forms a real, inverted image equal in size to the object. Where is the object placed? The object is placed at the centre of curvature, at a distance of 2F from the lens. The image forms at 2F on the other side, real, inverted, and the same size as the object.

Q5. Why is the resistance of a tungsten filament higher when hot than when cold? Resistance of metals increases with temperature. As the filament heats, atoms vibrate more and resist electron flow more strongly. This raises resistance significantly during operation.

Q6. How does the ozone layer protect life on Earth? The ozone layer absorbs most ultraviolet radiation from the sun. UV radiation causes skin cancer, cataracts, and DNA damage. Without the ozone layer, these rays would reach the Earth's surface directly.

Important Questions for Class 10 Science Chapter 1 to Chapter 13

Each chapter in CBSE 2026 Class 10 Science carries specific exam weight. Chapters like Life Processes, Electricity, and Light appear across multiple question formats, so prioritise those first.

Class 10 Science Important Questions with Answers: 2 Marks, 3 Marks and 5 Marks

CBSE 2026 Science papers divide questions into fixed marks categories. Each category tests a different depth of understanding. Practising by marks category trains students to write answers that match exactly what each format demands.

2-Mark Important Questions Class 10 Science

Two-mark answers need one direct statement and one supporting explanation. Keep answers to three or four lines.

Q1. What is a balanced chemical equation? Why is it important to balance equations? A balanced chemical equation has equal numbers of each atom on both sides. Balancing is important because matter cannot be created or destroyed. It follows the law of conservation of mass.

Q2. Name the part of the brain that controls posture and balance. The cerebellum controls posture and balance. It coordinates voluntary movements and ensures smooth, precise muscle activity.

Q3. Define power of a lens. State its SI unit. Power of a lens is the reciprocal of its focal length in metres. Its SI unit is dioptre (D). A convex lens has positive power; a concave lens has negative power.

3-Mark Important Questions Class 10 Science

Three-mark answers need a definition, an explanation, and one example or comparison. Answer structure matters as much as content here.

Q1. Explain the difference between autotrophic and heterotrophic nutrition with one example each. Autotrophic organisms make their own food using sunlight or chemical energy. Plants use photosynthesis to convert sunlight, water, and CO2 into glucose. Heterotrophic organisms depend on other organisms; humans digest food obtained from plants and animals.

Q2. What is the difference between acquired traits and inherited traits? Acquired traits develop during an organism's lifetime due to environment or activity. A bodybuilder's muscles are acquired and not passed to offspring. Inherited traits pass from parents to offspring through genes; eye colour is inherited.

Important 5 Marks Questions Class 10 Science

Five-mark answers need a full explanation, often with a diagram, comparison table, or step-by-step derivation. Practise writing these in full before the 2026 board exam.

Q1. With a labelled diagram, describe the structure and function of the human heart. The human heart has four chambers: two atria and two ventricles. The right atrium receives deoxygenated blood through the vena cava and passes it to the right ventricle. The right ventricle pumps it to the lungs through the pulmonary artery.

Oxygenated blood returns through the pulmonary vein to the left atrium. The left ventricle pumps it to the entire body through the aorta. Valves prevent backflow between chambers and the septum separates the left and right sides completely.

Diagram labels: right atrium, left atrium, right ventricle, left ventricle, aorta, pulmonary artery, pulmonary vein, vena cava, valves, septum.

Q2. Derive the relation between resistance, resistivity, length, and area of cross-section. Resistance R increases with length L: R is proportional to L. Resistance decreases as cross-sectional area A increases: R is proportional to 1/A. Combining both: R is proportional to L/A.

Introducing resistivity as the constant: R = pL/A. Resistivity depends on the material. Its SI unit is ohm-metre. A longer, thinner wire has higher resistance; a shorter, thicker wire has lower resistance.

Most Important Case-Based and Competency-Based Questions

CBSE 2026 board papers include case-based questions in every section. This format gives a real-world scenario and asks students to apply chapter knowledge to it. These questions cannot be answered by memorisation alone.

Case Study on Chemical Reactions

Case: Riya notices sugar dissolves faster in hot water than in cold. Stirring speeds it up further.

Q1. Is dissolving sugar a physical or chemical change? It is a physical change. No new substance forms. Sugar molecules disperse in water but their chemical composition stays unchanged.

Q2. Why does heat speed up dissolving? Heat increases kinetic energy of water molecules. Faster molecules collide with sugar particles more often and break them apart more quickly.

Q3. Name one other factor that affects the rate of dissolving. Stirring affects the rate of dissolving. It brings fresh solvent into contact with undissolved solute continuously.

Case Study on Electricity

Case: A student adds a second resistor in series and the bulb dims. She reconnects it in parallel and the bulb stays bright.

Q1. Why does the bulb dim in series? Total resistance increases in series. Higher resistance reduces circuit current. Lower current through the bulb produces less light.

Q2. Why does the bulb stay bright in parallel? Voltage across each component stays equal to the battery voltage in parallel. The bulb receives the same voltage and current, so brightness does not change.

Q3. Write the formula for total resistance in a parallel combination. 1/R = 1/R1 + 1/R2. Total resistance in parallel is always less than the smallest individual resistance.

How to Revise Class 10 Science Important Questions in the Last 10 Days

Ten days before the board exam, the strategy must shift from learning to consolidating. This plan works chapter by chapter and builds speed in the final stretch.

Days 1 to 6: Question-First Revision

Days 1 to 3: Attempt chapter-wise important questions for all 13 chapters. Do not read theory. Only attempt questions. Mark every answer you got wrong or left incomplete.

Days 4 to 6: Go back only to marked questions. For each wrong answer, read the relevant NCERT paragraph and then re-attempt. Do not re-read full chapters.

Days 7 to 10: Exam Simulation and Final Reinforcement

Days 7 to 8: Practise the important 5 marks questions class 10 science and all case-based questions from this page. These take the most time to write. Practising them now builds both speed and structure.

Day 9: Attempt one full sample paper under timed conditions using Sample Papers Class 10 Science. Review only wrong answers that night.

Day 10: Go through your formula list, diagram labels, and key definitions. No new questions. Only reinforce what you already know.