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Free study notes for CBSE & ICSE, Classes 6–12.

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BiologyClass 12CBSE

What Stops More Than One Sperm From Entering an Egg

Follow fertilisation with the acrosomal and cortical reactions and sex determination, trace cleavage to the blastocyst and implantation, understand the placenta's hormones and the landmarks of pregnancy, and explain parturition and lactation.

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BiologyClass 12CBSE

Why Sperm Come in Fours but Eggs Come Alone

Trace spermatogenesis and its control by GnRH, LH and FSH, describe the structure of a sperm and the composition of semen, follow oogenesis through the follicle stages, and link each phase of the menstrual cycle to its hormones.

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BiologyClass 12CBSE

Why the Testes Sit Outside the Body

Trace the organs, ducts and accessory glands of the male reproductive system, explore the seminiferous tubules and their Sertoli and Leydig cells, describe the female reproductive organs, and study the microscopic ovary and the mammary gland.

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BiologyClass 12CBSE

Why a Coconut Holds Both Liquid and Solid Endosperm

Compare free-nuclear and cellular endosperm and albuminous and non-albuminous seeds, name the parts of dicot and monocot embryos, see how ovules and ovaries become seeds and fruits, and understand apomixis, polyembryony and parthenocarpy.

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BiologyClass 12CBSE

Why Some Flowers Refuse Their Own Pollen

Classify pollination as autogamy, geitonogamy and xenogamy, match pollinating agents with floral adaptations, explain the devices that prevent self-pollination and the steps of artificial hybridisation, and follow pollen-pistil interaction to double fertilisation.

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BiologyClass 12CBSE

How a Flower Makes Pollen and an Embryo Sac

Relate the parts of a flower to gametophyte development, trace microsporogenesis inside the microsporangium, explore the structure and viability of pollen grains, and follow megasporogenesis from the ovule to the 7-celled, 8-nucleate embryo sac.

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ChemistryClass 12CBSE

Why Boiling an Egg Changes Its Proteins Forever

Classify amino acids and explain zwitterions and peptide bonds, describe the four levels of protein structure and denaturation, understand enzymes and vitamins with their deficiency diseases, and compare DNA and RNA and the roles of hormones.

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ChemistryClass 12CBSE

Why Table Sugar Fails the Test That Glucose Passes

Classify carbohydrates by size, carbonyl type and reducing power, work through the open-chain and ring structures of glucose and fructose with anomers, compare sucrose, maltose and lactose, and contrast starch, cellulose and glycogen.

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ChemistryClass 12CBSE

How Aniline Becomes the Colour in Your Clothes

Compare the basic strength of aliphatic and aromatic amines, use the carbylamine and Hinsberg tests, explain substitution in aniline and why Friedel-Crafts fails, and turn benzenediazonium chloride into halides, phenols and azo dyes.

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ChemistryClass 12CBSE

Why Stale Fish Smells the Way It Does

Understand the pyramidal structure, classification and naming of amines, prepare them by reduction and ammonolysis, make pure primary amines by Gabriel synthesis and Hoffmann bromamide degradation, and explain their boiling points and solubility.

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ChemistryClass 12CBSE

Why Vinegar Fizzes With Baking Soda but Alcohol Does Not

Name carboxylic acids and see why the carboxylate ion is resonance-stabilised, prepare acids by several routes, compare their acidity with phenols and alcohols including substituent effects, and follow their reactions from esters to decarboxylation and HVZ.

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ChemistryClass 12CBSE

How a Silver Mirror Reveals an Aldehyde

Understand nucleophilic addition to the carbonyl group and why aldehydes outpace ketones, work through additions of HCN, alcohols, ammonia derivatives and Grignard reagents, reductions and Tollens' and Fehling's tests, and aldol and Cannizzaro reactions.

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ChemistryClass 12CBSE

How Chemists Stop an Oxidation Exactly at the Aldehyde

Name aldehydes and ketones and understand the polar carbonyl group, prepare them from alcohols, alkenes and alkynes, make aldehydes selectively by the Rosenmund, Stephen, Etard and Gatterman-Koch reactions, and compare their physical properties.

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ChemistryClass 12CBSE

Why Phenol Is Acidic but Ethanol Is Not

Prepare phenol from haloarenes, benzenesulphonic acid, diazonium salts and cumene, explain its acidity and substituent effects, study its substitution, Kolbe and Reimer-Tiemann reactions, and prepare ethers and follow their reactions.

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ChemistryClass 12CBSE

Why Alcohols Boil So Much Higher Than Similar Hydrocarbons

Classify and name alcohols, phenols and ethers, prepare alcohols from alkenes, carbonyl compounds and Grignard reagents, explain their boiling points and solubility, and use their key reactions with the Lucas test.

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ChemistryClass 12CBSE

Why Some Reactions Flip a Molecule Inside Out Like an Umbrella

Contrast SN1 and SN2 substitution, predict inversion or racemisation using chirality, apply Saytzeff's rule with the Wurtz and Grignard reactions, and explain why haloarenes resist nucleophiles along with the uses and hazards of polyhalogen compounds.

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ChemistryClass 12CBSE

How Swapping One Hydrogen for a Halogen Transforms a Molecule

Classify and name haloalkanes and haloarenes, understand the polarity, length and strength of the carbon-halogen bond, and prepare halogen compounds from alcohols, hydrocarbons, halogen exchange and diazonium salts, with their physical properties.

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ChemistryClass 12CBSE

Why Ruby Is Red and Emerald Is Green

Predict hybridisation, shape and magnetism with valence bond theory, use crystal field splitting and the spectrochemical series to decide high or low spin, explain colour and magnetism, and understand synergic bonding in metal carbonyls and uses of complexes.

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ChemistryClass 12CBSE

Why Some Salts Keep Their Ions Locked Inside a Complex

Use Werner's theory to tell primary from secondary valence and double salts from coordination compounds, master the vocabulary of ligands and coordination number, write IUPAC names and formulas, and identify structural and stereoisomers of complexes.

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ChemistryClass 12CBSE

Why Purple Permanganate Turns Colourless in Acid

Learn the preparation, structure and oxidising reactions of potassium dichromate and potassium permanganate, see how pH controls the chromate-dichromate balance, and compare the lanthanoids and actinoids, including lanthanoid contraction and its consequences.

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ChemistryClass 12CBSE

Why Copper Sulphate Is Blue but Zinc Sulphate Is White

Place the d- and f-block elements in the periodic table and write their configurations with the chromium and copper exceptions, explain the physical properties of transition metals, and account for their oxidation states, colour, magnetism and catalysis.

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ChemistryClass 12CBSE

Why Some Reactions Always Take the Same Time to Halve

Derive and use the integrated rate equations for zero and first order reactions, including gas-phase and pseudo first order reactions, calculate half-lives, and apply the Arrhenius equation and collision theory to temperature and catalysts.

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ChemistryClass 12CBSE

Why Milk Sours Faster on a Hot Summer Day

Express reaction rates as average and instantaneous values, deduce rate laws and orders from experimental data with the units of the rate constant, tell order from molecularity, and see how concentration, temperature and catalysts change the rate.

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ChemistryClass 12CBSE

Why Iron Rusts Faster Near the Sea

Compare primary and secondary batteries through the dry cell, mercury cell, lead storage battery and nickel-cadmium cell, see how a hydrogen-oxygen fuel cell works, and explain the corrosion of iron and the ways to prevent it.

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