Class 10 · Science · English medium
Class 10 Science companion
An original companion to Science, NCERT Class 10 Science (2026–27 edition). Official textbook ↗ ncert.nic.in
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Chapters
- ENHinglish
Chapter 1: Chemical Reactions and Equations
Class 10 Science chapter 1. - ENHinglish
Chapter 2: Acids, Bases and Salts
Class 10 chemistry. Indicators (litmus, turmeric, methyl orange, phenolphthalein, olfactory) tell acids from bases. - ENHinglish
Chapter 3: Metals and Non-metals
Class 10 chemistry chapter on metals and non-metals. - ENHinglish
Chapter 4: Carbon and its Compounds
Carbon forms covalent bonds by sharing electrons, since gaining or losing four is too hard. - ENHinglish
Chapter 5: Life Processes
Class 10 biology chapter on life processes: nutrition, respiration, transportation and excretion, and why large organisms need organs and transport. - ENHinglish
Chapter 6: Control and Coordination
Class 10 biology chapter on control and coordination. - ENHinglish
Chapter 7: How do Organisms Reproduce?
Class 10 biology chapter on reproduction. - ENHinglish
Chapter 8: Heredity
Class 10 chapter on heredity. - ENHinglish
Chapter 9: Light – Reflection and Refraction
Reflection and refraction of light with the ray model. - ENHinglish
Chapter 10: The Human Eye and the Colourful World (Human Eye, Colourful World)
The eye forms a real, inverted image on the retina; the cornea does most of the bending and the ciliary muscles change the eye lens's focal - ENHinglish
Chapter 11: Electricity
Class 10 electricity. - ENHinglish
Chapter 12: Magnetic Effects of Electric Current (Magnetic Effects of Current)
Magnetic effects of current. - ENHinglish
Chapter 13: Our Environment
An ecosystem is all the organisms of an area plus their non-living surroundings, acting on one another.
Also in Hinglish
- Chapter 1: Chemical Reactions and Equations (Hinglish)
- Chapter 2: Acids, Bases and Salts (Hinglish)
- Chapter 3: Metals aur Non-metals (Hinglish)
- Chapter 4: Carbon and its Compounds (Hinglish)
- Chapter 5: Life Processes (Hinglish)
- Chapter 6: Control and Coordination (Hinglish)
- Chapter 7: Organisms Reproduce Kaise Karte Hain? (Hinglish)
- Chapter 8: Heredity (Hinglish)
- Chapter 9: Light – Reflection aur Refraction (Hinglish)
- Chapter 10: Human Eye aur Rangeen Duniya (Hinglish)
- Chapter 11: Electricity (Hinglish)
- Chapter 12: Electric Current ke Magnetic Effects (Hinglish)
- Chapter 13: Hamara Environment (Hinglish)
1
10 per cent lawदस प्रतिशत नियमOn average only about 10 % of the energy at one trophic level is passed on to the next.Ch 13 · Our EnvironmentA
abiotic componentअजैव घटकThe non-living part of an ecosystem, such as soil and its minerals, water, sunlight, wind and temperature.Ch 13 · Our Environmentacidअम्लA substance that gives hydrogen ions (H+) in water. Acids taste sour, turn blue litmus red and have a pH below 7.Ch 2 · Acids, Bases and Saltsaddition reactionसंकलन अभिक्रियाA reaction in which atoms add across a double or triple bond, as when vegetable oils are hydrogenated.Ch 4 · Carbon and its Compoundsaerobic respirationवायवीय श्वसनBreakdown of food using oxygen, completed in the mitochondria, giving carbon dioxide, water and a large amount of energy.Ch 5 · Life Processesalkaliक्षारA base that dissolves in water, giving hydroxide ions, such as sodium hydroxide.Ch 2 · Acids, Bases and SaltsallotropeअपररूपOne of the forms of an element in which its atoms are arranged differently; diamond and graphite are allotropes of carbon.Ch 4 · Carbon and its Compoundsalloyमिश्रातुA metal blended evenly with other metals or with a non-metal, such as brass or steel.Ch 3 · Metals and Non-metalsalveoliकूपिकाTiny thin-walled air sacs at the ends of the bronchioles, wrapped in capillaries, where gases are exchanged in the lungs.Ch 5 · Life ProcessesammeterऐमीटरA meter that measures current. It is joined in series, so the current being measured flows through it.Ch 11 · Electricityamphoteric oxideउभयधर्मी ऑक्साइडA metal oxide, such as Al2O3 or ZnO, that reacts with both acids and bases to give a salt and water.Ch 3 · Metals and Non-metalsanaerobic respirationअवायवीय श्वसनBreakdown of food without oxygen, giving ethanol and carbon dioxide (yeast) or lactic acid (muscle) and only a little energy.Ch 5 · Life Processesangle of deviationविचलन कोणThe angle between the incident ray and the emergent ray for light passing through a prism.Ch 10 · The Human Eye and the Colourful WorldantacidA mild base, such as milk of magnesia, taken to neutralise excess acid in the stomach.Ch 2 · Acids, Bases and Saltsatmospheric refractionवायुमंडलीय अपवर्तनBending of light by the air around the Earth, whose refractive index changes with height and from moment to moment.Ch 10 · The Human Eye and the Colourful Worldautotrophस्वपोषीAn organism that makes its own food from simple inorganic substances, as green plants do by photosynthesis.Ch 5 · Life Processesauxinऑक्सिनA plant hormone made at the shoot tip that makes cells lengthen; it collects on the shaded side of a shoot.Ch 6 · Control and CoordinationB
balanced equationसंतुलित समीकरणAn equation with the same number of atoms of each element on both sides. An unbalanced draft is a skeletal equation.Ch 1 · Chemical Reactions and Equationsbaseक्षारकA substance that reacts with an acid to give a salt and water. Bases turn red litmus blue; those that dissolve give OH- ions.Ch 2 · Acids, Bases and Saltsbiodegradableजैव निम्नीकरणीयAble to be broken down into simple substances by bacteria, fungi and other living things.Ch 13 · Our Environmentbiological magnificationजैव आवर्धनThe rise in concentration of a non-degradable chemical at each higher trophic level of a food chain.Ch 13 · Our Environmentbiotic componentजैव घटकThe living part of an ecosystem: plants, animals and microorganisms.Ch 13 · Our EnvironmentbuddingमुकुलनAsexual reproduction in which an outgrowth (bud) of the parent grows into a new individual and separates.Ch 7 · How do Organisms Reproduce?C
calcinationनिस्तापनHeating a carbonate ore strongly in little or no air to turn it into the oxide.Ch 3 · Metals and Non-metalscatenationशृंखलनThe ability of an element's atoms to bond to one another in chains, branches or rings; carbon shows it most strongly.Ch 4 · Carbon and its Compoundscentral nervous systemकेंद्रीय तंत्रिका तंत्रThe brain and the spinal cord, which receive information from the whole body and coordinate responses.Ch 6 · Control and Coordinationcentre of curvatureवक्रता केंद्रThe centre of the sphere of which a mirror (or a lens surface) is a part, marked C.Ch 9 · Light – Reflection and Refractionchemical equationरासायनिक समीकरणA reaction written with chemical formulae: reactants on the left, an arrow, products on the right.Ch 1 · Chemical Reactions and Equationschlor-alkali processElectrolysis of brine (sodium chloride solution) to make chlorine, hydrogen and sodium hydroxide.Ch 2 · Acids, Bases and Saltschlorofluorocarbons (CFCs)क्लोरोफ्लोरोकार्बनMan-made compounds of chlorine, fluorine and carbon, once used in fridges and sprays, that release ozone-destroying chlorine high in the atmosphere.Ch 13 · Our Environmentchromosomeगुणसूत्रA thread-like piece of DNA in the nucleus that carries many genes. Body cells have chromosomes in pairs.Ch 8 · Heredityciliary musclesपक्ष्माभी पेशियाँMuscles around the eye lens that change its curvature and so its focal length.Ch 10 · The Human Eye and the Colourful Worldcombination reactionसंयोजन अभिक्रियाTwo or more reactants join to form a single product.Ch 1 · Chemical Reactions and Equationscompass needleदिक्सूचक सुईA small, light magnet pivoted so that it can turn freely; its north pole points roughly towards geographic north.Ch 12 · Magnetic Effects of Electric Currentconcave mirrorअवतल दर्पणA spherical mirror whose reflecting surface curves inwards, facing the centre of the sphere.Ch 9 · Light – Reflection and Refractionconsumerउपभोक्ताAn organism that gets food by eating producers or other consumers.Ch 13 · Our Environmentcontraceptionगर्भनिरोधनAny method of preventing pregnancy, such as condoms, pills, a copper-T or surgery.Ch 7 · How do Organisms Reproduce?convex mirrorउत्तल दर्पणA spherical mirror whose reflecting surface bulges outwards.Ch 9 · Light – Reflection and Refractioncorneaस्वच्छ मंडलThe clear, curved front surface of the eye through which light enters; it does most of the bending of light.Ch 10 · The Human Eye and the Colourful Worldcorrosionसंक्षारणThe slow eating-away of a metal by air, moisture, acids or other substances around it.Ch 1 · Chemical Reactions and Equationscorrosionसंक्षारणThe slow eating away of a metal by air, moisture or chemicals around it; rusting of iron is an example.Ch 3 · Metals and Non-metalscovalent bondसहसंयोजी आबंधA bond formed when two atoms share a pair of electrons; two or three shared pairs make a double or triple bond.Ch 4 · Carbon and its CompoundsD
decomposerअपघटकA microorganism, mainly a bacterium or fungus, that feeds on dead matter and wastes and so releases their minerals back into soil and water.Ch 13 · Our Environmentdecomposition reactionवियोजन अभिक्रियाOne reactant breaks down into two or more simpler products.Ch 1 · Chemical Reactions and Equationsdihybrid crossA cross that follows two pairs of contrasting traits at once; its F2 shows a 9: 3: 3: 1 ratio.Ch 8 · HereditydilutionतनुकरणAdding water to an acid or base, which lowers the concentration of its ions.Ch 2 · Acids, Bases and Saltsdispersionविक्षेपणThe splitting of white light into its colours, because each colour bends by a different angle.Ch 10 · The Human Eye and the Colourful Worlddisplacement reactionविस्थापन अभिक्रियाA more reactive element takes the place of a less reactive one in its compound.Ch 1 · Chemical Reactions and EquationsDNAडीएनएDeoxyribonucleic acid: the molecule in chromosomes that carries the instructions for making a cell's proteins.Ch 7 · How do Organisms Reproduce?dominant traitप्रभावी लक्षणA trait that shows even when only one copy of its gene version is present, such as tallness in Tt peas.Ch 8 · Hereditydouble circulationदोहरा परिसंचरणCirculation in which blood passes through the heart twice in each complete round, once for the lungs and once for the body.Ch 5 · Life Processesdouble displacement reactionद्विविस्थापन अभिक्रियाTwo compounds exchange ions to form two new compounds.Ch 1 · Chemical Reactions and Equationsductileतन्यAble to be stretched into fine wire; gold can be drawn finer than any other metal.Ch 3 · Metals and Non-metalsE
earth wireभूसंपर्क तारA green safety wire that joins the metal body of an appliance to a metal plate buried in the ground.Ch 12 · Magnetic Effects of Electric Currentecosystemपारितंत्रAll the organisms of an area together with their non-living surroundings, acting on one another as one unit.Ch 13 · Our Environmentelectric circuitविद्युत परिपथAn unbroken, closed conducting path that lets charge flow from one terminal of a source back to the other.Ch 11 · Electricityelectric currentविद्युत धाराThe rate of flow of electric charge through a conductor, I = Q/t, measured in amperes (A).Ch 11 · Electricityelectric powerविद्युत शक्तिThe rate at which electrical energy is used or supplied, P = VI, measured in watts (W).Ch 11 · Electricityelectrolytic refiningविद्युत-अपघटनी परिष्करणPurifying a metal by electrolysis, with impure metal as the anode and pure metal as the cathode.Ch 3 · Metals and Non-metalselectromagnetविद्युत चुंबकA soft iron core inside a coil of insulated wire, which is a magnet only while current flows in the coil.Ch 12 · Magnetic Effects of Electric Currentendocrine glandअंतःस्रावी ग्रंथिA ductless gland that releases its hormones straight into the blood, such as the thyroid or the pancreas.Ch 6 · Control and Coordinationendothermic reactionऊष्माशोषी अभिक्रियाA reaction that takes in energy, usually as heat.Ch 1 · Chemical Reactions and EquationsenzymeएंजाइमA biological catalyst, usually a protein, that speeds up a chemical reaction in a living thing, such as amylase breaking down starch.Ch 5 · Life Processesesterificationएस्टरीकरणThe reaction of a carboxylic acid with an alcohol, using an acid catalyst, to give a sweet-smelling ester and water.Ch 4 · Carbon and its Compoundsexcretionउत्सर्जनThe removal of harmful wastes made by the body's own chemical reactions, such as urea and carbon dioxide.Ch 5 · Life Processesexothermic reactionऊष्माक्षेपी अभिक्रियाA reaction that gives out heat.Ch 1 · Chemical Reactions and EquationsF
far pointदूर बिंदुThe farthest point the eye can see clearly; at infinity for a normal eye.Ch 10 · The Human Eye and the Colourful Worldfeedback mechanismपुनर्भरण क्रियाविधिA control loop in which the effect of a hormone adjusts how much of it is released, as with insulin and blood sugar.Ch 6 · Control and CoordinationfertilisationनिषेचनFusion of a male gamete with a female gamete to form a zygote.Ch 7 · How do Organisms Reproduce?fissionविखंडनReproduction of a single cell by division: into two in binary fission, into many at once in multiple fission.Ch 7 · How do Organisms Reproduce?Fleming's left-hand ruleफ्लेमिंग का वामहस्त नियमWith the thumb and first two fingers of the left hand at right angles: first finger along the field, second finger along the current; the thumb gives the force.Ch 12 · Magnetic Effects of Electric Currentfocal lengthफोकस दूरीThe distance from the pole of a mirror, or the optical centre of a lens, to its principal focus.Ch 9 · Light – Reflection and Refractionfood chainआहार श्रृंखलाA sequence of organisms in which each one is eaten by the next, starting with a producer.Ch 13 · Our Environmentfood webआहार जालA network of interlinked food chains in an ecosystem.Ch 13 · Our Environmentfunctional groupप्रकार्यात्मक समूहAn atom or group of atoms, such as –OH or –COOH, that decides the chemical properties of a carbon compound.Ch 4 · Carbon and its Compoundsfuseफ़्यूज़A short wire of low melting point joined in series with a circuit; it melts and breaks the circuit if the current gets too large.Ch 11 · Electricityfuseविद्युत फ्यूज़A short wire of low melting point in series with the live wire; it melts and breaks the circuit when the current is too large.Ch 12 · Magnetic Effects of Electric CurrentG
galvanisationयशदलेपनGiving iron or steel a thin coat of zinc to stop it rusting.Ch 3 · Metals and Non-metalsgameteयुग्मकA germ cell (sperm or egg) with half the usual number of chromosomes, made by meiosis.Ch 7 · How do Organisms Reproduce?gangueगैंगThe soil, sand and rock mixed with an ore, removed before the metal is extracted.Ch 3 · Metals and Non-metalsgeneजीनA stretch of DNA with the instructions for one protein. Genes control traits and are inherited in pairs.Ch 8 · Hereditygenotypeजीनप्ररूपAn organism's gene make-up for a trait, written as its pair of gene copies, such as TT, Tt or tt.Ch 8 · Hereditygeotropismगुरुत्वानुवर्तनDirectional growth in response to gravity: roots grow downwards, shoots upwards.Ch 6 · Control and Coordinationgerm cellजनन कोशिकाA reproductive cell (egg, sperm or pollen) carrying one member of every chromosome pair: half the number in a body cell.Ch 8 · HeredityH
haemoglobinहीमोग्लोबिनThe red, oxygen-carrying pigment in red blood cells; it picks up oxygen in the lungs and releases it in the tissues.Ch 5 · Life ProcessesheredityआनुवंशिकताThe passing on of traits from parents to offspring, by rules that make offspring reliably resemble their parents.Ch 8 · HeredityheterotrophविषमपोषीAn organism that takes in complex food made by other organisms, such as an animal or a fungus.Ch 5 · Life Processeshomologous seriesसमजातीय श्रेणीA family of compounds with the same functional group in which successive members differ by a CH2 unit (14 u).Ch 4 · Carbon and its Compoundshormoneहॉर्मोनA chemical messenger made in one part of an organism that travels to another part and changes what the cells there do.Ch 6 · Control and Coordinationhydronium ionहाइड्रोनियम आयनThe ion H3O+: a hydrogen ion joined to a water molecule, the form H+ takes in water.Ch 2 · Acids, Bases and Saltshypermetropiaदीर्घ-दृष्टि दोषNear objects blur because their image would form behind the retina; corrected by a convex lens.Ch 10 · The Human Eye and the Colourful WorldI
indicatorसूचकA substance whose colour (or smell) is different in acids and in bases, such as litmus, methyl orange or phenolphthalein.Ch 2 · Acids, Bases and Saltsionic compoundआयनिक यौगिकA compound of positive and negative ions held by electrostatic attraction, formed by electron transfer from a metal to a non-metal.Ch 3 · Metals and Non-metalsJ
Joule's law of heatingजूल का तापन नियमThe heat produced in a resistor is H = I²Rt.Ch 11 · ElectricityK
kilowatt hourकिलोवाट घंटाThe commercial unit of electrical energy (one unit): 1 kW used for 1 h, equal to 3.6 × 10⁶ J.Ch 11 · ElectricityL
lensलेंसA transparent piece of material bounded by two surfaces, at least one of them spherical. Convex lenses converge light; concave lenses diverge it.Ch 9 · Light – Reflection and Refractionlife processesजैव प्रक्रमThe basic activities, such as nutrition, respiration, transportation and excretion, that keep an organism maintained and alive.Ch 5 · Life Processeslive wireविद्युन्मय तारThe mains wire at high potential (220 V relative to neutral); red in the older Indian colour code.Ch 12 · Magnetic Effects of Electric CurrentM
magnetic fieldचुंबकीय क्षेत्रThe region around a magnet or a current in which a magnetic force can be detected. It has both strength and direction.Ch 12 · Magnetic Effects of Electric Currentmagnetic field lineचुंबकीय क्षेत्र रेखाA line along which a small compass needle would point; its arrow shows the way the north pole points.Ch 12 · Magnetic Effects of Electric Currentmagnificationआवर्धनThe ratio of image height to object height, m = h′/h; its sign shows whether the image is inverted (−) or erect (+).Ch 9 · Light – Reflection and Refractionmalleableआघातवर्ध्यAble to be beaten or rolled into thin sheets without breaking, as gold, silver and aluminium are.Ch 3 · Metals and Non-metalsmenstruationऋतुस्रावThe monthly shedding of the thickened uterine lining, as blood and mucus, when no embryo has implanted.Ch 7 · How do Organisms Reproduce?metallurgyधातुकर्मGetting metals out of their ores and purifying them for use.Ch 3 · Metals and Non-metalsmicelleमिसेलA ball of soap molecules in water with the oily tails inside and the ionic heads outside; it can hold oily dirt.Ch 4 · Carbon and its CompoundsmineralखनिजA naturally formed element or compound found in the Earth's crust.Ch 3 · Metals and Non-metalsmonohybrid crossA cross that follows one pair of contrasting traits, such as tall and short; its F2 shows a 3: 1 ratio.Ch 8 · Hereditymyopiaनिकट-दृष्टि दोषDistant objects blur because their image forms in front of the retina; corrected by a concave lens.Ch 10 · The Human Eye and the Colourful WorldN
near pointनिकट बिंदुThe closest point at which the eye sees clearly without strain; about 25 cm for a normal young eye.Ch 10 · The Human Eye and the Colourful Worldnephronवृक्काणुThe filtering unit of the kidney: a glomerulus inside Bowman's capsule, followed by a tubule where useful substances are reabsorbed.Ch 5 · Life Processesneuronतंत्रिका कोशिकाA nerve cell, specialised to carry information as electrical impulses; it has dendrites, a cell body and an axon.Ch 6 · Control and Coordinationneutral wireउदासीन तारThe return wire of the mains supply, kept close to the potential of the earth; black in the older colour code.Ch 12 · Magnetic Effects of Electric CurrentneutralisationउदासीनीकरणThe reaction in which an acid and a base cancel each other, forming a salt and water.Ch 2 · Acids, Bases and Saltsnon-biodegradableअजैव निम्नीकरणीयNot broken down by living things, so it lasts for years or even centuries.Ch 13 · Our EnvironmentO
Ohm's lawओम का नियमFor a metal conductor at a steady temperature, the current is proportional to the potential difference: V = IR.Ch 11 · Electricityolfactory indicatorगंधीय सूचकA substance whose smell changes in an acid or a base, such as onion, vanilla or clove oil.Ch 2 · Acids, Bases and Saltsoptical centreप्रकाशिक केंद्रThe central point of a lens on its principal axis; a ray through it is not deviated.Ch 9 · Light – Reflection and Refractionoreअयस्कA mineral from which a metal can be extracted profitably.Ch 3 · Metals and Non-metalsoverloadingअतिभारणDrawing more current from a circuit than it is designed to carry, for example by running too many appliances on it.Ch 12 · Magnetic Effects of Electric CurrentoxidationउपचयनGain of oxygen or loss of hydrogen by a substance.Ch 1 · Chemical Reactions and Equationsoxidising agentउपचायकA substance that adds oxygen to another substance, such as alkaline potassium permanganate.Ch 4 · Carbon and its Compoundsozone layerओज़ोन परतThe region of the upper atmosphere, about 15–35 km up, rich in ozone (O3), that absorbs most of the Sun's ultraviolet radiation.Ch 13 · Our EnvironmentP
parallel connectionपार्श्वक्रमParts joined between the same two points, so each has the same potential difference across it.Ch 11 · Electricityperipheral nervous systemपरिधीय तंत्रिका तंत्रThe cranial nerves from the brain and the spinal nerves from the spinal cord, linking the CNS with the rest of the body.Ch 6 · Control and CoordinationpH scaleA scale from 0 to 14 for acidity: 7 is neutral, below 7 acidic, above 7 basic. A lower pH means more hydrogen ions.Ch 2 · Acids, Bases and Saltsphenotypeलक्षणप्ररूपThe form of a trait that we can see, such as tall or short. It depends on the genotype.Ch 8 · Heredityphotosynthesisप्रकाश संश्लेषणThe making of carbohydrates from carbon dioxide and water by green plants, using sunlight absorbed by chlorophyll, with oxygen given out.Ch 5 · Life Processesphototropismप्रकाशानुवर्तनDirectional growth in response to light: shoots grow towards it, roots away from it.Ch 6 · Control and CoordinationplacentaअपराA disc of tissue in the uterine wall through which the embryo gets food and oxygen and passes out wastes.Ch 7 · How do Organisms Reproduce?poleध्रुवThe middle point of a spherical mirror's shiny face, labelled P.Ch 9 · Light – Reflection and RefractionpollinationपरागणTransfer of pollen grains from an anther to a stigma, of the same flower or another flower.Ch 7 · How do Organisms Reproduce?potential differenceविभवांतरThe work done to move one coulomb of charge between two points, V = W/Q, measured in volts (V).Ch 11 · Electricitypower of a lensलेंस की क्षमताThe reciprocal of focal length in metres, P = 1/f, measured in dioptres (D).Ch 9 · Light – Reflection and Refractionpower of accommodationसमंजन क्षमताHow the eye lens changes its focal length so that both near and far objects come into focus.Ch 10 · The Human Eye and the Colourful Worldprecipitateअवक्षेपAn insoluble solid that forms in a solution during a reaction.Ch 1 · Chemical Reactions and Equationspresbyopiaजरा-दूरदृष्टिताLoss of accommodation with age, so the near point moves away; corrected by convex or bifocal lenses.Ch 10 · The Human Eye and the Colourful Worldprincipal axisमुख्य अक्षThe straight line joining P and C of a mirror, or C₁ and C₂ of a lens. It is normal to the mirror at P.Ch 9 · Light – Reflection and Refractionprincipal focusमुख्य फोकसThe point where rays parallel to the principal axis meet, or seem to come from, after reflection or refraction.Ch 9 · Light – Reflection and Refractionproducerउत्पादकAn organism that makes its own food from simple substances using sunlight, such as a green plant or an alga.Ch 13 · Our Environmentproductउत्पादA new substance formed in a reaction.Ch 1 · Chemical Reactions and EquationspubertyयौवनारंभThe stage of adolescence when the reproductive tissues mature and signs of sexual maturity appear.Ch 7 · How do Organisms Reproduce?Punnett squareA grid that pairs every kind of germ cell from one parent with every kind from the other, to show the expected offspring.Ch 8 · Hereditypure-breedingDescribes plants that, when self-pollinated, give offspring like themselves for a trait, generation after generation.Ch 8 · HeredityR
rancidityविकृतगंधिताThe spoiling of fats and oils in food by oxidation, which changes their smell and taste.Ch 1 · Chemical Reactions and EquationsreactantअभिकारकA substance that is used up and changed in a reaction.Ch 1 · Chemical Reactions and Equationsreactivity seriesसक्रियता श्रेणीA list of metals from the most reactive (potassium) to the least reactive (gold), with hydrogen placed in it for comparison.Ch 3 · Metals and Non-metalsreal imageवास्तविक प्रतिबिंबAn image formed where rays actually meet; it can be caught on a screen.Ch 9 · Light – Reflection and Refractionreceptorग्राहीA specialised nerve-cell tip, usually in a sense organ, that detects one kind of stimulus.Ch 6 · Control and Coordinationrecessive traitअप्रभावी लक्षणA trait that shows only when both gene copies are of that version, such as shortness in tt peas.Ch 8 · HeredityreductionअपचयनLoss of oxygen or gain of hydrogen by a substance. It always pairs with oxidation (a redox reaction).Ch 1 · Chemical Reactions and Equationsreflex actionप्रतिवर्ती क्रियाA quick, automatic response to a stimulus, made without conscious thought, such as blinking.Ch 6 · Control and Coordinationreflex arcप्रतिवर्ती चापThe path of a reflex: receptor, sensory neuron, relay neuron in the spinal cord, motor neuron, effector.Ch 6 · Control and Coordinationrefractionअपवर्तनThe change in direction of light when it passes at a slant from one transparent medium into another.Ch 9 · Light – Reflection and Refractionrefractive indexअपवर्तनांकHow many times faster light travels in vacuum than in a given medium: n = c/v.Ch 9 · Light – Reflection and Refractionregenerationपुनरुद्भवनGrowth of a whole organism, or a lost part, from a body piece by cells that multiply and develop.Ch 7 · How do Organisms Reproduce?resistanceप्रतिरोधHow strongly a conductor opposes the flow of charge, R = V/I, measured in ohms (Ω).Ch 11 · Electricityresistivityप्रतिरोधकताA property of a material, ρ = RA/l, that fixes the resistance of a wire of given size; unit ohm metre (Ω m).Ch 11 · Electricityretinaदृष्टिपटलThe light-sensitive layer at the back of the eye on which the image forms.Ch 10 · The Human Eye and the Colourful Worldrheostatधारा नियंत्रकA variable resistor with a sliding contact, used to change the current without changing the source.Ch 11 · Electricityright-hand thumb ruleदक्षिण-हस्त अंगुष्ठ नियमGrip a current-carrying wire in the right hand with the thumb along the current; the curled fingers show the direction of the field lines.Ch 12 · Magnetic Effects of Electric Currentroastingभर्जनHeating a sulphide ore strongly in plenty of air to turn it into the oxide.Ch 3 · Metals and Non-metalsS
saltलवणA compound formed when the hydrogen of an acid is replaced by a metal or ammonium ion, for example in neutralisation.Ch 2 · Acids, Bases and SaltssaponificationसाबुनीकरणThe splitting of an ester by an alkali into an alcohol and the salt of the acid; it is how soap is made.Ch 4 · Carbon and its Compoundssaturated compoundसंतृप्त यौगिकA carbon compound with only single bonds between its carbon atoms, such as ethane.Ch 4 · Carbon and its Compoundsscattering of lightप्रकीर्णनLight being sent off in many directions when it strikes small particles.Ch 10 · The Human Eye and the Colourful Worldseries connectionश्रेणीक्रमParts joined end to end in one chain, so the same current flows through each.Ch 11 · Electricitysex chromosomesलिंग गुणसूत्रThe chromosome pair that decides sex in humans: XX in females and XY in males.Ch 8 · Heredityshort circuitलघुपथनA fault in which the live and neutral wires touch directly, so the resistance falls almost to zero and the current becomes very large.Ch 12 · Magnetic Effects of Electric CurrentsolenoidपरिनालिकाA long, tightly wound coil of insulated wire with many turns, shaped like a tube.Ch 12 · Magnetic Effects of Electric Currentspectrumस्पेक्ट्रमThe band of colours (VIBGYOR) obtained by dispersing white light.Ch 10 · The Human Eye and the Colourful WorldsporeबीजाणुA tiny thick-walled reproductive cell that survives harsh conditions and grows when it lands somewhere moist.Ch 7 · How do Organisms Reproduce?stimulusउद्दीपनA change in the surroundings or inside the body that a living thing can detect and respond to, such as light, heat or a smell.Ch 6 · Control and Coordinationstomataरंध्रTiny pores, mostly on the underside of leaves, through which gases enter and leave; each is opened and closed by two guard cells.Ch 5 · Life Processesstrong acidप्रबल अम्लAn acid that splits almost completely into ions in water, such as HCl. A weak acid, such as acetic acid, splits only partly.Ch 2 · Acids, Bases and Saltsstructural isomersसंरचनात्मक समावयवीCompounds with the same molecular formula but different structures, such as butane and 2-methylpropane.Ch 4 · Carbon and its Compoundssubstitution reactionप्रतिस्थापन अभिक्रियाA reaction in which one atom or group in a molecule takes the place of another, such as Cl replacing H in methane.Ch 4 · Carbon and its Compoundssynapseसिनैप्सThe narrow gap between the nerve ending of one neuron and the next cell, crossed by chemical messengers.Ch 6 · Control and CoordinationT
tetravalencyचतुःसंयोजकताHaving a valency of four: each carbon atom forms four covalent bonds.Ch 4 · Carbon and its Compoundstraitलक्षणA feature of an organism, such as height, seed shape or earlobe type. Inherited traits pass from parents to offspring.Ch 8 · Hereditytranslocationस्थानांतरणThe movement of food made in the leaves, and other substances, through the phloem to other parts of a plant.Ch 5 · Life Processestranspirationवाष्पोत्सर्जनLoss of water as vapour from the parts of a plant above the ground, mainly through stomata; it pulls water up the xylem.Ch 5 · Life Processestrophic levelपोषी स्तरA feeding step in a food chain; producers form the first level.Ch 13 · Our Environmenttropismअनुवर्तनGrowth of a plant part towards (positive) or away from (negative) a stimulus such as light, gravity, water or a chemical.Ch 6 · Control and CoordinationTyndall effectटिंडल प्रभावScattering of light by small particles that makes the path of a beam visible.Ch 10 · The Human Eye and the Colourful WorldU
uniform magnetic fieldएकसमान चुंबकीय क्षेत्रA field with the same strength and direction everywhere in a region, drawn as straight, parallel, equally spaced lines.Ch 12 · Magnetic Effects of Electric Currentuniversal indicatorसार्वत्रिक सूचकA mixture of indicators that shows a different colour at each pH.Ch 2 · Acids, Bases and Saltsunsaturated compoundअसंतृप्त यौगिकA carbon compound with at least one double or triple bond between carbon atoms, such as ethene.Ch 4 · Carbon and its CompoundsV
variationविभिन्नताA difference between individuals of the same species; new variations arise when DNA is not copied perfectly.Ch 7 · How do Organisms Reproduce?variationविभिन्नताDifferences between individuals of the same species, such as in height or colour. Many arise during reproduction and are inherited.Ch 8 · Heredityvegetative propagationकायिक प्रवर्धनGrowth of a new plant from a root, stem or leaf of the parent, without seeds.Ch 7 · How do Organisms Reproduce?virtual imageआभासी प्रतिबिंबAn image formed where rays only appear to meet; it cannot be caught on a screen.Ch 9 · Light – Reflection and Refractionvoltmeterवोल्टमीटरA meter that measures potential difference. Its two leads are joined in parallel across the two points.Ch 11 · ElectricityW
water of crystallisationक्रिस्टलन जलWater locked into a salt's crystals in a fixed ratio to the salt, as in CuSO4.5H2O.Ch 2 · Acids, Bases and SaltsZ
zygoteयुग्मनजThe cell formed when a male and a female gamete fuse; it divides to form the embryo.Ch 7 · How do Organisms Reproduce?ncert.ai is an independent learning companion aligned to the NCERT curriculum. It is not affiliated with or endorsed by NCERT.