CBSE Class 10 Science Important Questions Chapter Wise 2026-27

Welcome to your guide for CBSE Class 10 Science Important Questions Chapter Wise. I am a CBSE board examiner and a content strategist so I put this list together just to help you make your study time much easier. I know that Science can feel like much to handle sometimes. However if you focus on the topics the competency-based questions and the main ideas you can really get a top score, in Science.

This resource is optimized for both quick revision and in-depth board preparation, covering Physics, Chemistry, and Biology. Let’s dive into the chapter-wise breakdown.

Chapter 1: Chemical Reactions and Equations

Important Topics

Balancing chemical equations
Types of reactions (Combination, Decomposition, Displacement, Double Displacement, Oxidation-Reduction)
Effects of oxidation in everyday life (Corrosion and Rancidity)

Most Important Questions (MIQs) & Conceptual Questions

Why do we apply paint on iron articles? (Short Answer)
What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube? Write the balanced chemical equation and name the type of reaction. (Short Answer)
A shiny brown colored element ‘X’ on heating in air becomes black in color. Name the element ‘X’ and the black colored compound formed. (Conceptual)

Chemical Equation/Reaction Questions

Translate the following statements into chemical equations and then balance them: (a) Barium chloride reacts with aluminium sulphate to give aluminium chloride and barium sulphate. (b) Hydrogen gas combines with nitrogen to form ammonia.
Write the chemical equation for the reaction of zinc with dilute hydrochloric acid.

Assertion-Reason Questions Q: Assertion (A): Decomposition of vegetable matter into compost is an exothermic reaction. Reason (R): Exothermic reactions are those in which heat is evolved along with the formation of products. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

A student added dilute HCl to a test tube containing zinc granules and observed a gas. How can he test the gas evolved? What type of reaction is this? Write the equation.

Quick Revision Points

Reactions requiring heat, light, or electricity to occur are endothermic.
Corrosion of silver is called tarnishing (forms Ag₂S).
To prevent rancidity, antioxidants are added to food, and chips are flushed with nitrogen gas.

Chapter 2: Acids, Bases and Salts

Important Topics

pH scale and its importance
Reactions of metal carbonates/hydrogen carbonates with acids
Chlor-alkali process and bleaching powder preparation

Most Important Questions (MIQs) & Conceptual Questions

State the chemical property in each case shown by the action of: (i) Water on quicklime (ii) Dilute acid on zinc granules.
Why does distilled water not conduct electricity, whereas rain water does? (Conceptual)

Chemical Equation/Reaction Questions

Write the chemical formula of washing soda. How is it prepared? Write its two uses.
What happens when an acid reacts with a metal oxide? Explain with an example.

Assertion-Reason Questions Q: Assertion (A): Bleaching powder releases chlorine gas when exposed to air. Reason (R): Bleaching powder reacts with CO₂ and moisture present in the air. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

A milkman adds a very small amount of baking soda to fresh milk. (a) Why does he do so? (b) What happens to the pH of fresh milk when it turns into curd?

Quick Revision Points

pH = 7 (neutral), < 7 (acidic), > 7 (basic).
Plaster of Paris (CaSO₄.½H₂O) must be stored in a moisture-proof container to prevent hydration into Gypsum.
Sodium hydroxide and Hydrochloric acid are produced in the Chlor-alkali process.

Chapter 3: Metals and Non-metals

Important Topics

Reactivity series
Extraction of metals (Roasting, Calcination, Refining)
Galvanization and Alloying

Most Important Questions (MIQs) & Conceptual Questions

Why do ionic compounds have high melting points?
Give reasons: (a) Platinum, gold, and silver are used to make jewelry. (b) Sodium, potassium, and lithium are stored under kerosene oil.

Chemical Equation/Reaction Questions

Differentiate between roasting and calcination with balanced equations.
What is thermite reaction? Write its use.

Assertion-Reason Questions Q: Assertion (A): Carbonate and sulphide ores are usually converted into oxides during extraction. Reason (R): It is easier to obtain a metal from its oxide as compared to its sulphide or carbonate. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

You are given a hammer, a battery, a bulb, wires, and a switch. How will you distinguish between a sample of metal and non-metal based on their physical and chemical properties?

Quick Revision Points

Aqua Regia is a mixture of concentrated HCl and concentrated HNO₃ in a 3:1 ratio. It dissolves gold and platinum.
Solder is an alloy of lead and tin (low melting point).
Amphoteric oxides react with both acids and bases to produce salt and water (e.g., Al₂O₃, ZnO).

Chapter 4: Carbon and its Compounds

Important Topics

IUPAC Nomenclature
Isomerism (Chain, Position, Functional group)
Properties of Ethanol and Ethanoic acid
Soaps and Detergents

Most Important Questions (MIQs) & Conceptual Questions

What is a homologous series? Explain with an example.
Why are carbon and its compounds used as fuels for most applications?

Chemical Equation/Reaction Questions

Write the next higher homologue of C₃H₇OH. Give the IUPAC name of the given compound and draw its structure.
Write the equation for the reaction of ethanol with sodium metal.

Assertion-Reason Questions Q: Assertion (A): Detergents are more effective than soaps in hard water. Reason (R): The calcium and magnesium salts of detergents are soluble in water. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

A compound ‘X’ has the molecular formula C₂H₄O₂. It reacts with sodium bicarbonate to liberate CO₂. Identify ‘X’, write its structure, and write the chemical equation for the reaction.

Quick Revision Points

Ethanol reacts with ethanoic acid in the presence of conc. H₂SO₄ to form an ester (Esterification reaction).
Hydrogenation of vegetable oils uses Nickel as a catalyst to make fats.
Soaps form insoluble scum in hard water, whereas detergents form soluble substances.

Chapter 5: Life Processes

Important Topics

Photosynthesis mechanism
Human digestive system
Human respiratory system
Excretion in humans (Nephron)

Most Important Questions (MIQs) & Conceptual Questions

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Where do plants get each of the raw materials required for photosynthesis?
Explain the process of breakdown of glucose in a cell in the absence of oxygen.

Chemical Equation/Reaction Questions

Write the balanced equation for the process of photosynthesis. What are the conditions necessary for it?

Assertion-Reason Questions Q: Assertion (A): The inner lining of the small intestine has millions of tiny finger-like projections called villi. Reason (R): Villi increase the surface area for absorption of digested food. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

Case-Based: A patient complains of severe stomach pain. The doctor diagnoses it as an ulcer caused by H. pylori. Explain how the stomach protects itself from its own digestive juices normally, and how the liver and pancreas assist the small intestine in digestion.

Important Diagrams

Human Heart (Pulmonary and Systemic circulation)
Nephron structure
Open and closed stomata

Quick Revision Points

Salivary amylase breaks down starch into simple sugars in the mouth.
Blood vessels (arteries) carry oxygenated blood except the pulmonary artery.
Haemoglobin binds with oxygen to transport it.

Chapter 6: Control and Coordination

Important Topics

Structure and function of Neuron
Reflex action and arc
Plant hormones (Auxins, Gibberellins, Cytokinins, ABA)
Endocrine glands (Pituitary, Thyroid, Pancreas, Adrenal)

Most Important Questions (MIQs) & Conceptual Questions

What is the difference between a reflex action and walking?
How does chemical coordination occur in plants? Give examples.
Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron, but not the reverse?

Assertion-Reason Questions Q: Assertion (A): The growth of a plant shoot towards light is called phototropism. Reason (R): Auxin accumulates on the shaded side of the shoot, promoting cell elongation on that side. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

A doctor advises a patient to take an injection of insulin. Which gland is not functioning properly in the patient? Name the disease and the hormone responsible.

Important Diagrams

Reflex Arc
Structure of a Neuron
Human Brain (Lateral view)

Quick Revision Points

The gap between two neurons is called a synapse.
Thyroxine regulates carbohydrate, protein, and fat metabolism. Iodine is essential for its synthesis.
Adrenaline is the ‘fight or flight’ hormone.

Chapter 7: How do Organisms Reproduce?

Important Topics

Pollination and fertilization in flowering plants
Male and female reproductive systems
Menstrual cycle
Methods of contraception

Most Important Questions (MIQs) & Conceptual Questions

What is the role of the seminal vesicle and the prostate gland?
Why is variation beneficial to the species but not necessarily for the individual?
How does the embryo get nourishment inside the mother’s body?

Assertion-Reason Questions Q: Assertion (A): The placenta is a vital connection between the mother and the developing fetus. Reason (R): It provides oxygen and nutrients to the fetus and removes waste products. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

In a bisexual flower, despite having both male and female parts, cross-pollination is preferred. Explain the mechanisms by which plants prevent self-pollination.

Important Diagrams

Longitudinal section of a flower
Human male reproductive system
Human female reproductive system

Quick Revision Points

Binary fission occurs in Amoeba; multiple fission in Plasmodium.
Regeneration occurs in Planaria and Hydra.
The lining of the uterus thickens every month to receive the fertilized egg.

Chapter 8: Heredity

Important Topics

Mendel’s laws of inheritance
Monohybrid and Dihybrid crosses
Sex determination in humans
Acquired vs. Inherited traits

Most Important Questions (MIQs) & Conceptual Questions

How do Mendel’s experiments show that traits may be dominant or recessive?
How is the sex of a child determined in human beings?
Give an example of characteristics in the traits of peas that are determined by two genes.

Assertion-Reason Questions Q: Assertion (A): Traits acquired during the lifetime of an individual are not inherited. Reason (R): Changes in non-reproductive tissues cannot be passed on to the DNA of germ cells. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

A pure tall pea plant (TT) is crossed with a pure dwarf pea plant (tt). Work out the cross up to F2 generation. State the phenotypic and genotypic ratios.

Important Diagrams

Mechanism of sex determination (XX and XY chromosomes)

Quick Revision Points

Gregor Mendel chose the garden pea (Pisum sativum) for his experiments.
Humans have 23 pairs of chromosomes (22 pairs autosomes, 1 pair sex chromosomes).
Father determines the sex of the child.

Chapter 9: Light – Reflection and Refraction

Important Topics

Laws of reflection and refraction
Mirror formula and magnification
Lens formula and power of a lens
Sign convention

Most Important Questions (MIQs) & Conceptual Questions

State the laws of refraction of light.
An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.
Why do we prefer a convex mirror as a rear-view mirror in vehicles?

Important Numericals

A concave lens has a focal length of 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens? Also, find the magnification.
An object 5 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position and size of the image.

Assertion-Reason Questions Q: Assertion (A): A convex mirror always produces a virtual, erect, and diminished image. Reason (R): The focal length of a convex mirror is positive. Answer: Both A and R are true but R is not the correct explanation of A.

Competency-Based Questions

A lens forms an image at ‘v’ when the object is at ‘u’. If the object is moved closer by 10 cm, where will the new image form? Show mathematically.

Important Diagrams

Ray diagrams for image formation by Concave/Convex mirrors.
Ray diagrams for image formation by Convex/Concave lenses.

Quick Revision Points

Refractive index of a medium = Speed of light in vacuum / Speed of light in medium.
Power = 1 / Focal length (in meters). Unit: Dioptre.
For a concave mirror, ‘f’ is negative; for a convex mirror, ‘f’ is positive.

Chapter 10: The Human Eye and the Colourful World

Important Topics

Defects of vision (Myopia, Hypermetropia, Presbyopia)
Dispersion and scattering of light
Atmospheric refraction (Tyndall effect)

Most Important Questions (MIQs) & Conceptual Questions

What is the far point and near point of the human eye with normal vision?
A student has difficulty reading the blackboard while sitting in the last row. What defect of vision is he suffering from? How can it be corrected? Draw the ray diagram.
Why does the sky appear blue?

Assertion-Reason Questions Q: Assertion (A): Stars twinkle but planets do not. Reason (R): Planets are much closer to Earth than stars, so they act as extended sources of light. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

The danger signals installed at the top of tall buildings are red in color. Explain the scattering of light reasoning behind this choice of color.

Important Diagrams

Defects of vision and their correction using lenses.
Dispersion of white light through a glass prism.

Quick Revision Points

The least distance of distinct vision is 25 cm for a normal eye.
Rainbow formation is due to dispersion, refraction, and internal reflection of sunlight by water droplets.
Red light is least scattered by fog/smoke (longest wavelength).

Chapter 11: Electricity

Important Topics

Ohm’s Law
Series and Parallel circuits
Electric Power and Heating effect
Resistivity

Most Important Questions (MIQs) & Conceptual Questions

Why is the tungsten used almost exclusively for filament of electric lamps?
Why are the conductors of electric heating devices made of an alloy rather than a pure metal?
Draw a schematic diagram of a circuit consisting of a battery of three cells of 2V each, a 5Ω resistor, an 8Ω resistor, and a 12Ω resistor all in parallel, plugged with a key and ammeter.

Important Numericals

Two resistors of 4Ω and 6Ω are connected in parallel. This combination is connected to a battery of 12V. Find the total current drawn from the battery and the current through each resistor.
An electric bulb is rated 220V and 100W. When it is operated on 110V, find the power consumed.
Calculate the heat generated when an electric iron of resistance 20Ω is operated on a 220V supply for 2 hours.

Assertion-Reason Questions Q: Assertion (A): A fuse wire is always connected in series with the live wire. Reason (R): Fuse wire melts and breaks the circuit when current exceeds a safe limit. Answer: Both A and R are true and R is the correct explanation of A.

Competency-Based Questions

A student’s house has frequent electrical short-circuits. Explain the physics behind a short circuit and suggest two safety measures commonly used to prevent them.

Quick Revision Points

V = IR (Ohm’s Law).
H = I²Rt (Joule’s Law of Heating).
Resistivity depends on the nature of the material, not its dimensions.

Chapter 12: Magnetic Effects of Electric Current

Important Topics

Right-Hand Thumb Rule
Force on a current-carrying conductor in a magnetic field (Fleming’s Left-Hand Rule)
Electromagnetic Induction (Fleming’s Right-Hand Rule)
Domestic electric circuits (Live, Neutral, Earth wire)

Most Important Questions (MIQs) & Conceptual Questions

What is the function of an earth wire? Why is it necessary to earth metallic appliances?
State the rule to find the direction of force acting on a current-carrying conductor placed in a magnetic field.
Explain the principle and working of an electric motor.

Assertion-Reason Questions Q: Assertion (A): A current-carrying conductor experiences a force in a magnetic field. Reason (R): The magnetic field exerts pressure on the conductor causing it to move. Answer: Both A and R are true but R is not the exact correct explanation of A (The force is due to the interaction of the two magnetic fields).

Competency-Based Questions

A student wants to test if a given piece of metal is a magnet. Using a battery, wire, and compass, explain how they can determine the polarity of a magnet using electromagnetic principles.

Important Diagrams

Magnetic field lines around a bar magnet.
Magnetic field lines due to a current-carrying circular loop/solenoid.
Domestic electric circuit.

Quick Revision Points

Alternating Current (AC) reverses direction; Direct Current (DC) flows in one direction.
Electric fuse is based on the heating effect of current.
A solenoid behaves like an electromagnet.

👉 Download CBSE Class 10 Science Important Questions & Answers PDF

Most Important Numericals

1. Light (Chapter 9): An object 4 cm in height is placed at a distance of 15 cm from a concave mirror of focal length 10 cm. Find the position, nature, and size of the image formed. (Ans: v = -30 cm, Image is real, inverted, 8 cm tall)

2. Light (Chapter 9): A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? (Ans: u = -30 cm)

3. Electricity (Chapter 11): A wire of length 2 m and area of cross-section 1 mm² has a resistance of 2Ω. What will be the resistance of another wire of the same material having length 4 m and area of cross-section 2 mm²? (Ans: 2Ω)

4. Electricity (Chapter 11): An electric heater rated 1000 W operates at 220 V. Calculate the current drawn by the heater. If the heater is used for 2 hours daily, calculate the energy consumed in a day. (Ans: I = 4.54 A, E = 2 kWh)

Most Important Diagrams

Biology: Human Heart (Label pulmonary veins, aorta, ventricles).
Biology: Nephron (Label glomerulus, Bowman’s capsule, renal tubule).
Biology: Reflex Arc.
Biology: Longitudinal Section of a Flower.
Physics: Image formation by a Concave Mirror when the object is between F and 2F.
Physics: Magnetic Field lines around a Solenoid.

7-Day Science Revision Strategy

Day 1: Chemistry (Ch 1 & 2) – Focus on equations, balancing, and salts.
Day 2: Chemistry (Ch 3 & 4) – Focus on extraction, nomenclature, and carbon reactions.
Day 3: Biology (Ch 5 & 6) – Focus on Life Processes diagrams and nervous system.
Day 4: Biology (Ch 7 & 8) – Focus on reproduction and Mendelian crosses.
Day 5: Physics (Ch 9 & 10) – Focus on numericals, ray diagrams, and defects of vision.
Day 6: Physics (Ch 11 & 12) – Focus on circuits, Ohm’s law, and magnetic fields.
Day 7: Solve CBSE Sample Papers and Previous Year Question Papers. Time yourself.

Frequently Asked Questions

Q1: Are NCERT questions enough for scoring 90+ in CBSE Class 10 Science?

A: Yes, NCERT is the bible. However, in Physics, practice extra numericals. In Biology, read between the lines. For Chemistry, practice balancing and direct reactions thoroughly.

Q2: How do I manage time during the Science board exam?

A: Allocate 30 mins for Section A (MCQs & VSA), 45 mins for Section B (SA), 45 mins for Section C (LA), and 30 mins for Section D (Case-based). Keep the last 30 minutes for revising and completing diagrams.

Q3: Which chapter carries the highest weightage?

A: Generally, “Chemical Reactions” (Ch 1), “Life Processes” (Ch 5), and “Electricity” (Ch 11) carry the highest weightage across different sections.

Conclusion

Getting marks in the CBSE Class 10 Science exam is all about having a good plan understanding your concepts and practicing every single day. I made this CBSE Class 10 Science Important Questions Chapter Wise guide to help you focus on what matters so you do not waste time on things that will not show up on the test. Make sure you focus on the numericals practice your diagrams and memorize your chemical equations. If you do these things you can trust your preparation. I wish you the best of luck, for your board exams!