Class 10 Science

Here you can find Class 10 Science Notes. These notes include important revision points, simple explanations.

Chapter 1. Chemical Reactions and Equations 

This chapter explains how substances undergo chemical changes to form new substances through chemical reactions. It helps students identify chemical reactions by observing changes such as colour change, gas evolution, temperature change, or formation of a precipitate. The chapter introduces the correct way of representing reactions using word equations and balanced chemical equations, highlighting the importance of the law of conservation of mass. It also discusses different types of chemical reactions and their effects in everyday life, including corrosion and rancidity. 

Key Points

• A chemical reaction involves the conversion of reactants into products.

• Chemical reactions are identified by observable changes like colour change, gas evolution, temperature change, or precipitate formation.

• A word equation represents a reaction using words.

• A chemical equation uses symbols and formulae to represent reactions.

• A skeletal equation is an unbalanced chemical equation.

• Balanced chemical equations follow the law of conservation of mass.

• Physical states of substances are shown using (s), (l), (g), and (aq).

• Combination reactions form a single product from two or more reactants.

• Decomposition reactions break a compound into simpler substances.

• Displacement reactions occur when a more reactive element replaces a less reactive one.

• Double displacement reactions involve exchange of ions between compounds.

• Oxidation is gain of oxygen or loss of hydrogen.

• Reduction is loss of oxygen or gain of hydrogen.

• Oxidation and reduction occur together and are called redox reactions.

• Corrosion is the slow destruction of metals by reaction with air, moisture, or chemicals.

• Rancidity is the oxidation of fats and oils causing spoilage of food.

👉 👉Chemical reactions explain the changes happening all around us, from rusting of iron to digestion of food. Understanding chemical equations and reaction types helps us control reactions, prevent damage like corrosion, preserve food, and apply chemistry safely and responsibly in daily life and industry.

Chapter 2. Acids, Bases and Salts 

This chapter explains how acids, bases, and salts are important chemical substances used in daily life. It describes their properties, chemical behaviour, and reactions, helping students understand how these substances affect our surroundings. The chapter discusses acids and bases in aqueous solutions, their strength, and the role of pH scale in measuring acidity and basicity. It also explains the preparation, properties, and uses of common salts such as washing soda, baking soda, bleaching powder, plaster of Paris, and common salt, highlighting their importance in homes, industries, and health.

Key Points

• Acids are substances that produce hydrogen ions (H⁺) in aqueous solutions.

• Bases produce hydroxide ions (OH⁻) in aqueous solutions.

• Salts are formed by the neutralisation reaction between an acid and a base.

• Acids and bases show their properties only in the presence of water.

• Acids turn blue litmus red, while bases turn red litmus blue.

• Metal oxides are generally basic, while non-metal oxides are acidic.

• Acids react with metals to form salt and hydrogen gas.

• Acids react with metal carbonates and bicarbonates to produce carbon dioxide.

• Bases react with acids to form salt and water (neutralisation).

• The pH scale measures acidity or basicity on a scale of 0 to 14.

• pH less than 7 indicates an acidic solution, pH equal to 7 is neutral, and pH greater than 7 is basic.

• Strong acids and bases can be harmful and must be handled carefully.

• pH of soil and water affects plants, crops, and aquatic life.

• Common salts like washing soda, baking soda, and plaster of Paris have wide domestic and industrial uses.

• Excessive acidity or basicity in the environment can damage living organisms.

👉 👉Acids, bases, and salts play an essential role in daily life, from food and medicines to cleaning and industry. By understanding their properties and the concept of pH, we can use these substances safely, wisely, and responsibly, while protecting our health and the environment.

Chapter 3. Metals and Non-metals 

This chapter explains how elements are broadly classified into metals and non-metals based on their physical and chemical properties. It describes why metals are widely used in daily life due to their strength, conductivity, and malleability, while non-metals play an equally important role in life processes and industries. The chapter discusses the reactivity series, methods of extraction of metals from ores, and the importance of corrosion prevention. It also highlights how metals and non-metals are essential for technological development and sustainable use of natural resources.

Key Points

• Elements are classified as metals, non-metals, and metalloids.

• Metals are generally lustrous, hard, malleable, ductile, and good conductors of heat and electricity.

• Non-metals are usually dull, brittle, and poor conductors of heat and electricity.

• Malleability allows metals to be beaten into thin sheets.

• Ductility allows metals to be drawn into wires.

• Sonority is the property by which metals produce a ringing sound.

• Metals form positive ions (cations) by losing electrons.

• Non-metals form negative ions (anions) by gaining electrons.

• Reactivity series arranges metals in decreasing order of reactivity.

• Highly reactive metals are found in combined form in nature.

• Less reactive metals can be found in free state.

• Extraction of metals depends on their position in the reactivity series.

• Ores are minerals from which metals can be extracted profitably.

• Corrosion is the gradual destruction of metals due to air and moisture.

• Rusting is corrosion of iron in presence of air and water.

• Corrosion can be prevented by painting, galvanisation, oiling, or alloying.

• Alloys are mixtures of metals or metals with non-metals that improve properties.

• Metals and non-metals are vital for industry, health, agriculture, and technology.

👉 👉Metals and non-metals are invaluable natural resources that support modern life and technology. By understanding their properties, extraction, and proper use, we can reduce waste, prevent damage like corrosion, and ensure responsible and sustainable use of Earth’s resources for the future.

Chapter 4. Carbon and Its Compounds  

This chapter explains the central role of carbon in forming a vast variety of substances essential for life and industry. It describes why carbon is unique due to its ability to form strong covalent bonds and long chains through catenation. The chapter introduces different forms of carbon, basic organic compounds, and important groups like hydrocarbons, alcohols, and carboxylic acids. It also explains everyday substances such as fuels, soaps, and detergents, showing how chemistry directly connects with daily life, health, and the environment.

Key Points

• Carbon has the ability to form a large number of compounds.

• Carbon forms covalent bonds by sharing electrons.

• Catenation allows carbon atoms to link with each other to form long chains.

• Allotropes of carbon include diamond, graphite, and fullerenes.

• Diamond is very hard and does not conduct electricity.

• Graphite is soft and a good conductor of electricity.

• Organic compounds mainly contain carbon and hydrogen.

• Hydrocarbons are compounds made only of carbon and hydrogen.

• Saturated hydrocarbons contain single bonds, while unsaturated hydrocarbons contain double or triple bonds.

• Homologous series is a group of compounds with similar chemical properties.

• Functional groups decide the chemical nature of organic compounds.

• Alcohols and carboxylic acids are important functional groups.

• Ethanol is a common alcohol used as fuel and solvent.

• Ethanoic acid is found in vinegar.

• Soaps and detergents are cleansing agents used to remove dirt and grease.

• Soaps are biodegradable, while detergents work better in hard water.

👉 👉Carbon chemistry shows how simple atoms can create complex and useful substances. By understanding carbon compounds, we learn to use fuels wisely, choose eco-friendly products, and apply science responsibly for a healthier and sustainable future.

Chapter 5. Life Processes 

This chapter explains how living organisms carry out essential activities that are necessary to maintain life. It describes life processes such as nutrition, respiration, transportation, and excretion, which continue even when an organism is at rest. The chapter highlights how these processes provide energy, maintain internal balance, and remove waste materials. It explains differences in life processes among plants and animals, unicellular and multicellular organisms, and shows how specialised organs and tissues work together to keep the body alive and functioning efficiently.

Key Points

• Life processes are activities needed to maintain life.

• Living organisms show internal molecular movement, even if no visible movement is seen.

• Nutrition provides energy and raw materials for growth and repair.

• Autotrophic nutrition occurs in green plants through photosynthesis.

• Photosynthesis uses carbon dioxide, water, sunlight, and chlorophyll to make food.

• Heterotrophic nutrition depends on other organisms for food.

• Animals show different feeding methods such as holozoic, parasitic, and saprophytic nutrition.

• Digestion in humans occurs in the alimentary canal, with the help of enzymes.

• Respiration releases energy from food.

• Aerobic respiration uses oxygen and releases more energy.

• Anaerobic respiration occurs without oxygen and releases less energy.

• Transportation moves food, oxygen, hormones, and wastes in the body.

• The heart, blood, and blood vessels form the human transport system.

• Plants use xylem to transport water and minerals.

• Plants use phloem to transport food by translocation.

• Excretion removes harmful metabolic wastes from the body.

• Kidneys filter blood and form urine using nephrons.

• Plants remove wastes through transpiration, storage, and shedding leaves.

👉 👉Life depends on continuous and well-coordinated processes. Understanding life processes helps us appreciate how our body and plants function efficiently and reminds us to maintain a healthy lifestyle and protect living systems responsibly.

Chapter 6. Control and Coordination 

This chapter explains how living organisms control and coordinate their activities and responses to changes in the environment. It describes the two main systems of control in animals—the nervous system and the endocrine (hormonal) system—and explains how plants respond to stimuli without nerves or muscles. The chapter highlights how quick responses are managed through electrical impulses, while slow and long-lasting responses occur through chemical signals (hormones). Together, these systems help organisms survive, grow, and maintain balance within the body.

Key Points

• Control and coordination help organisms respond properly to environmental changes.

• Movement in living organisms is often a response to a stimulus.

• In animals, control is achieved through the nervous system and hormones.

• The nervous system uses electrical impulses for fast responses.

• Receptors detect stimuli such as light, heat, sound, smell, and taste.

• Neurons transmit impulses through dendrites, cell body, axon, and synapse.

• Reflex actions are quick, automatic responses that do not involve thinking.

• Reflex arcs are formed in the spinal cord for faster responses.

• The brain is the main coordinating centre of the body.

• The forebrain controls thinking and voluntary actions.

• The midbrain and hindbrain control involuntary actions like breathing and heartbeat.

• The cerebellum maintains posture, balance, and precision of movements.

• The spinal cord protects reflex pathways and connects the brain to the body.

• Muscles move by changing shape due to special contractile proteins.

• Plants respond to stimuli through growth movements and non-growth movements.

• Tropic movements in plants are directional growth responses to stimuli.

• Phototropism, geotropism, hydrotropism, and chemotropism are types of tropisms.

• Plant hormones like auxin, gibberellin, cytokinin, and abscisic acid regulate growth.

• Animals use hormones for slow but widespread coordination.

• Adrenaline prepares the body for emergency situations.

• Thyroxin, growth hormone, insulin, testosterone, and oestrogen regulate growth and metabolism.

• Feedback mechanisms control hormone levels in the body.

👉 👉Efficient control and coordination are essential for survival. By working together, the nervous system and hormonal system ensure proper responses, balanced growth, and internal stability. Understanding these systems helps us appreciate how the body and plants function in a highly organised and intelligent manner.

Chapter 7. How do Organisms Reproduce?  

This chapter explains reproduction as a fundamental life process by which organisms produce new individuals of their own kind. It describes why reproduction is essential for the continuity of species and how it introduces variation, which is important for evolution. The chapter discusses different modes of reproduction, including asexual reproduction and sexual reproduction, with examples from plants, animals, and humans, helping students understand growth, development, and reproductive health.

Key Points

• Reproduction is the process by which organisms produce new individuals.

• It is not essential for the survival of an individual but is necessary for the survival of a species.

• DNA copying is a basic event in reproduction and leads to inheritance of traits.

• Minor variations occur during DNA copying, which are useful for evolution.

• Asexual reproduction involves only one parent and produces genetically similar offspring.

• Fission occurs in unicellular organisms like Amoeba and Plasmodium.

• Binary fission produces two daughter cells, while multiple fission produces many.

• Fragmentation occurs when an organism breaks into pieces, each growing into a new individual.

• Regeneration is the ability to regrow lost body parts, seen in Planaria and Hydra.

• Budding involves the formation of a small outgrowth that develops into a new organism.

• Vegetative propagation in plants uses roots, stems, or leaves to form new plants.

• Spore formation occurs in fungi like Rhizopus, where spores grow under favorable conditions.

• Sexual reproduction involves two parents and leads to greater variation.

• Meiosis produces gametes with half the number of chromosomes.

• In flowering plants, reproduction occurs through pollination and fertilisation.

• In humans, reproductive organs mature during puberty.

• Fertilisation results in the formation of a zygote, which develops into an embryo.

• Menstruation occurs when the egg is not fertilised.

• Contraceptive methods help in family planning and reproductive health.

👉 👉Reproduction ensures the continuity of life on Earth. Understanding different reproductive methods helps us appreciate biological diversity, make informed choices about reproductive health, and respect the natural processes that support evolution and survival of species.

Chapter 8. Heredity   

This chapter explains how traits and characteristics are passed from parents to offspring through the process of reproduction. It describes how variations arise and accumulate over generations, leading to diversity among living organisms. The chapter introduces the basic rules of inheritance discovered by Gregor Mendel, explaining concepts such as dominant and recessive traits, genes, and chromosomes. It also explains how traits are inherited independently, how genes control the expression of characteristics, and how sex determination takes place in human beings.

Key Points

• Heredity is the transfer of traits from parents to offspring.

• Variations arise during reproduction and may be inherited.

• Variations help organisms survive in changing environments.

• Asexual reproduction produces fewer variations than sexual reproduction.

• Genes are units of inheritance present on DNA.

• Each gene controls a specific trait.

• In sexual reproduction, offspring inherit two copies of each gene, one from each parent.

• Gregor Mendel studied inheritance using pea plants.

• A dominant trait expresses itself even if one copy is present.

• A recessive trait expresses itself only when both copies are recessive.

• Mendel showed that traits are inherited in fixed patterns.

• Traits for different characters can be inherited independently of each other.

• Chromosomes carry genes and occur in pairs in body cells.

• Gametes contain only one set of chromosomes.

• Fertilisation restores the normal chromosome number.

• In humans, sex determination depends on the X and Y chromosomes.

• Females have XX chromosomes, while males have XY chromosomes.

• The father determines the sex of the child.

👉 👉Heredity helps us understand how life continues with both similarities and differences. By learning how traits are inherited and how variations arise, we gain insight into diversity, evolution, and the responsibility of respecting and protecting life in all its forms.

Chapter 9. Light – Reflection and Refraction 

This chapter explains how light behaves when it falls on surfaces and travels through different media. It introduces the phenomena of reflection and refraction, which help us understand how images are formed by mirrors and lenses. The chapter explains the laws of reflection, the working of spherical mirrors, and the formation of images using ray diagrams. It also describes refraction of light, refractive index, and the functioning of glass slabs and lenses. These concepts help explain everyday experiences like seeing our image in mirrors, bending of light in water, and the working of optical devices.

Key Points

• Light is a form of energy that enables us to see objects.

• Reflection of light occurs when light bounces back from a surface.

• The laws of reflection state that:

• The angle of incidence equals the angle of reflection.

• The incident ray, reflected ray, and normal lie in the same plane.

• Plane mirrors form images that are virtual, erect, and same size.

• Spherical mirrors are of two types: concave and convex.

• Concave mirrors can form real or virtual images depending on object position.

• Convex mirrors always form virtual, erect, and diminished images.

• Ray diagrams help locate the position and nature of images.

• Refraction of light is the bending of light when it passes from one medium to another.

• Refraction occurs due to a change in the speed of light in different media.

• The refractive index measures how much light bends in a medium.

• A glass slab shows refraction but the emergent ray is parallel to the incident ray.

• Lenses are transparent optical devices that refract light.

• Convex lenses converge light rays.

• Concave lenses diverge light rays.

• Image formation by lenses depends on the position of the object.

• Magnification tells how large or small the image is compared to the object.

• These principles are used in spectacles, cameras, microscopes, and telescopes.

👉 👉Light helps us understand the world visually. By learning how light reflects and refracts, we gain insight into natural phenomena and technological devices. This knowledge teaches us how science transforms simple observations into powerful tools that improve daily life and vision care.

Chapter 10. The Human Eye and the Colourful World  

This chapter explains how the human eye works as a natural optical instrument that enables us to see the colourful world around us. It describes the structure of the eye, the concept of accommodation, and how images are formed on the retina. The chapter also discusses common defects of vision and their correction using suitable lenses. Further, it explains beautiful natural phenomena related to light, such as dispersion, rainbow formation, atmospheric refraction, twinkling of stars, and scattering of light, helping us understand why the sky appears blue and the Sun looks red during sunrise and sunset.

Key Points

• The human eye is a sensitive sense organ that enables vision.

• Light enters the eye through the cornea and forms an image on the retina.

• The eye lens forms a real and inverted image on the retina.

• Ciliary muscles change the curvature of the eye lens.

• Power of accommodation is the ability of the eye to focus on near and distant objects.

• The near point of a normal eye is about 25 cm.

• The far point of a normal eye is at infinity.

• Cataract causes clouding of the eye lens in old age.

• Myopia (near-sightedness) makes distant objects appear blurred.

• Myopia is corrected using a concave lens.

• Hypermetropia (far-sightedness) makes nearby objects appear blurred.

• Hypermetropia is corrected using a convex lens.

• Presbyopia occurs due to weakening of ciliary muscles with age.

• Bi-focal lenses help correct presbyopia.

• A prism bends light due to refraction.

• Dispersion is the splitting of white light into VIBGYOR colours.

• A rainbow is formed due to refraction, dispersion, and internal reflection of sunlight in raindrops.

• Atmospheric refraction causes twinkling of stars.

• Stars twinkle because they appear as point sources of light.

• Planets do not twinkle as they appear as extended sources.

• Advance sunrise and delayed sunset occur due to atmospheric refraction.

• Scattering of light causes the blue colour of the sky.

• Blue light is scattered more because it has shorter wavelength.

• The Sun appears red at sunrise and sunset due to scattering of shorter wavelengths.

👉 👉The human eye and natural light phenomena show how beautifully science explains nature. Understanding vision and light helps us care for our eyes, appreciate natural wonders like rainbows and blue skies, and apply scientific knowledge responsibly to improve life and technology.

Chapter 11. Electricity  

This chapter explains electricity as a vital and controllable form of energy used in daily life. It introduces electric current, electric circuits, potential difference, and resistance, and explains their relationships through Ohm’s law. The chapter further discusses series and parallel combinations of resistors, the heating effect of electric current, Joule’s law of heating, and electric power, helping students understand how electrical devices work safely and efficiently.

Key Points

• Electric current is the flow of electric charges through a conductor.

• A closed electric circuit is necessary for current to flow.

• Electric current (I) is defined as the rate of flow of charge: I = Q/t.

• The SI unit of current is ampere (A).

• Potential difference (V) is the work done per unit charge: V = W/Q.

• The SI unit of potential difference is volt (V).

• Ammeter measures current and is connected in series.

• Voltmeter measures potential difference and is connected in parallel.

• Ohm’s Law states that V ∝ I, or V = IR, at constant temperature.

• Resistance (R) opposes the flow of current; its unit is ohm (Ω).

• Resistance depends on length, area of cross-section, and material.

• Resistivity (ρ) is a material property and is independent of dimensions.

• In series combination, total resistance increases: Rs = R₁ + R₂ + R₃.

• In parallel combination, total resistance decreases: 1/Rp = 1/R₁ + 1/R₂ + 1/R₃.

• Heating effect of electric current converts electrical energy into heat.

• Joule’s law of heating: H = I²Rt.

• Heating effect is used in electric irons, heaters, bulbs, and fuses.

• Electric power (P) is the rate of consumption of electrical energy.

• P = VI = I²R = V²/R.

• The SI unit of power is watt (W).

• Commercial unit of electrical energy is kilowatt-hour (kWh) or unit.

• Parallel circuits are preferred in homes for safety and proper functioning.

👉 👉Understanding electricity helps us use electrical energy safely, efficiently, and economically. Knowledge of circuits, resistance, and power prevents accidents, reduces energy waste, and forms the foundation for modern technology and responsible energy usage.

Chapter 12. Magnetic Effects of Electric Current   

This chapter explains the close relationship between electricity and magnetism. It describes how an electric current produces a magnetic field and how this magnetic field can exert a force on a current-carrying conductor. The chapter introduces important rules such as the Right-Hand Thumb Rule and Fleming’s Left-Hand Rule, and explains devices like the electromagnet, electric motor, and fuse. It also discusses the role of magnetic fields in daily-life applications and the importance of electrical safety in domestic circuits.

Key Points

• Electric current flowing through a conductor produces a magnetic field around it.

• The region around a magnet or current-carrying conductor where magnetic force is felt is called a magnetic field.

• Magnetic field lines represent the strength and direction of the magnetic field.

• Magnetic field lines emerge from the north pole and enter the south pole outside the magnet.

• Magnetic field lines never intersect each other.

• The magnetic field around a straight current-carrying conductor forms concentric circles.

• The strength of the magnetic field increases with increase in current.

• The strength of the magnetic field decreases with increase in distance from the conductor.

• Right-Hand Thumb Rule helps determine the direction of the magnetic field around a conductor.

• A circular current-carrying loop produces a stronger magnetic field at its centre.

• A solenoid is a coil of many turns of insulated copper wire.

• A current-carrying solenoid behaves like a bar magnet.

• An electromagnet is formed by placing a soft iron core inside a solenoid.

• The strength of an electromagnet can be controlled by changing current and number of turns.

• A current-carrying conductor placed in a magnetic field experiences a force.

• Fleming’s Left-Hand Rule gives the direction of force on a current-carrying conductor.

• An electric motor converts electrical energy into mechanical energy.

• Domestic electric circuits use live wire, neutral wire, and earth wire.

• A fuse protects electrical circuits from overloading and short-circuiting.

• A fuse works on the heating effect of electric current.

👉 👉Understanding the magnetic effects of electric current helps us safely use electrical devices and appreciate how electricity powers machines and technology. Proper knowledge of magnetic fields, motors, and safety devices promotes responsible energy use and protects both people and appliances.

Chapter 13. Our Environment    

This chapter explains the meaning of the environment and how living organisms and non-living components interact to maintain balance in nature. It introduces the concept of an ecosystem, its biotic and abiotic components, and explains how energy flows through food chains and food webs. The chapter also highlights serious environmental concerns such as biological magnification, ozone layer depletion, and waste management, helping students understand how human activities affect the environment and why sustainable practices are essential.

Key Points

• The environment includes all living and non-living things around us.

• An ecosystem is formed by the interaction of living organisms with their physical surroundings.

• Ecosystems have biotic components (plants, animals, microorganisms) and abiotic components (air, water, soil, temperature).

• Producers are green plants that make food using photosynthesis.

• Consumers depend directly or indirectly on producers for food.

• Decomposers break down dead organisms and recycle nutrients back to the soil.

• A food chain shows who eats whom in an ecosystem.

• Each step in a food chain is called a trophic level.

• Energy transfer between trophic levels follows the 10% law.

• Only about 10% of energy is passed to the next trophic level.

• Due to energy loss, food chains are usually short.

• A food web is a network of interconnected food chains.

• Energy flow in an ecosystem is unidirectional.

• Harmful chemicals like pesticides enter food chains and accumulate.

• Biological magnification is the increase in concentration of harmful substances at higher trophic levels.

• Humans are most affected as they occupy the top trophic level.

• The ozone layer protects Earth from harmful ultraviolet (UV) radiation.

• CFCs are responsible for ozone layer depletion.

• Ozone depletion increases risks like skin cancer and ecological damage.

• Waste can be biodegradable or non-biodegradable.

• Non-biodegradable waste persists in the environment for long periods.

• Improper waste disposal causes serious environmental pollution.

• Reduce, Reuse, and Recycle help manage waste effectively.

👉 👉Nature works as a balanced system, and human actions strongly influence it. By understanding ecosystems, conserving resources, reducing waste, and protecting the ozone layer, we can live responsibly and ensure a healthy environment for future generations.