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| Classwise Science MCQ Questions with Solutions (Class 12th) | ||||||||||||||
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Class 12th Chemistry MCQ Questions
1. The Solid State
This chapter explores the **solid state of matter**, focusing on the arrangement and properties of particles in solids. It classifies solids into crystalline and amorphous types. Crystalline solids are further categorized based on bonding (ionic, covalent, metallic, molecular) and crystal lattices (**unit cells**). Concepts like close packing in 1D, 2D, and 3D, coordination number, and common crystal structures (like FCC, BCC, simple cubic) are discussed. The chapter also covers imperfections or **defects** in solids (point defects, line defects) and their impact on electrical and magnetic properties, explaining concepts like semiconductors and ferroelectricity.
2. Solutions
This chapter deals with **solutions**, which are homogeneous mixtures of two or more components. It covers various ways to express solution **concentration**, such as molarity ($\textsf{M}$), molality ($\textsf{m}$), mole fraction ($\chi$), and mass/volume percentages. **Raoult's Law**, describing the vapour pressure of solutions, is discussed, along with ideal and non-ideal solutions. The chapter details **colligative properties** – properties dependent on the number of solute particles, not their identity – including relative lowering of vapour pressure, elevation of boiling point ($\Delta \textsf{T}_\text{b}$), depression of freezing point ($\Delta \textsf{T}_\text{f}$), and **osmotic pressure** ($\pi = \textsf{CRT}$). Abnormal molar masses and the **Van't Hoff factor** are also covered.
3. Electrochemistry
**Electrochemistry** studies the relationship between chemical energy and electrical energy. This chapter introduces **electrochemical cells**, where chemical reactions produce electricity (**Galvanic cells**) or electricity drives chemical reactions (**Electrolytic cells**). Concepts like electrode potential, **standard electrode potential** ($E^\circ$), and the **Nernst equation** are used to calculate cell potential. Electrolytic conductivity ($\kappa$), molar conductivity ($\Lambda_\text{m}$), and their variation with concentration are discussed, along with **Kohlrausch's Law**. Electrolysis, **Faraday's laws**, different types of batteries (primary, secondary), fuel cells, and the phenomenon of **corrosion** and its prevention are also covered.
4. Chemical Kinetics
**Chemical kinetics** deals with the rates of chemical reactions and the factors influencing them. This chapter defines reaction rate and discusses how it is affected by concentration, temperature, catalyst, and surface area. The **rate law**, rate constant ($\textsf{k}$), **order of reaction**, and molecularity are introduced. Integrated rate equations for zero and first-order reactions are derived, along with the concept of **half-life** ($t_{1/2}$). Collision theory and the concept of **activation energy** ($E_\text{a}$) are explained to understand reaction mechanisms, culminating in the **Arrhenius equation** ($\textsf{k} = \textsf{A}e^{-\textsf{E}_\text{a}/\textsf{RT}}$).
5. Surface Chemistry
This chapter explores phenomena occurring at surfaces or interfaces. It discusses **adsorption**, the accumulation of molecular species on the surface rather than in the bulk, distinguishing between physisorption and chemisorption. Factors affecting adsorption and the **Freundlich adsorption isotherm** are covered. **Catalysis**, the process where a substance (catalyst) alters reaction rate without being consumed, is discussed, including homogeneous and heterogeneous catalysis and enzyme catalysis. The chapter also introduces **colloids**, heterogeneous mixtures with particle sizes between true solutions and suspensions, describing their classification, preparation, properties (Tyndall effect, Brownian movement, electrophoresis), and uses, including **emulsions**.
6. General Principles And Processes Of Isolation Of Elements
This chapter focuses on **metallurgy**, the science and technology of extracting metals from their ores and refining them for use. It discusses common occurrences of metals and the various steps involved in the **extraction of elements**: **concentration** of ore, **conversion** of concentrated ore into oxide, and **reduction** of the oxide to metal. Different methods of reduction (e.g., smelting, electrolytic reduction) and refining processes (e.g., distillation, zone refining, electrolytic refining) are explained. The chapter illustrates these principles with the extraction of common metals like Aluminium ($\textsf{Al}$), Iron ($\textsf{Fe}$), Copper ($\textsf{Cu}$), and Zinc ($\textsf{Zn}$), highlighting the chemical reactions and physical processes involved.
7. The P-Block Elements
This chapter provides a detailed study of the chemistry of the **p-block elements** across Groups 15, 16, 17, and 18 of the Periodic Table. It discusses their general electronic configurations, oxidation states, and trends in physical and chemical properties. Key topics include the preparation, properties, and uses of important compounds like ammonia ($\textsf{NH}_3$), nitric acid ($\textsf{HNO}_3$), phosphorus allotropes, sulfur (allotropes, sulfuric acid $\textsf{H}_2\textsf{SO}_4$), halogens ($\textsf{F}_2, \textsf{Cl}_2, \textsf{Br}_2, \textsf{I}_2$, interhalogen compounds), and noble gases (e.g., Xenon compounds like $\textsf{XeF}_2, \textsf{XeF}_4$). The anomalous behaviour of the first element of each group is also discussed.
8. The D-And F-Block Elements
This chapter focuses on the properties and chemistry of the **transition elements** (d-block) and **inner transition elements** (f-block), including Lanthanoids and Actinoids. It discusses their electronic configurations and general characteristics of transition elements such as metallic nature, variable oxidation states, formation of **coloured ions**, catalytic properties, and magnetic properties (paramagnetism, diamagnetism, ferromagnetism). The preparation and properties of important compounds like Potassium Permanganate ($\textsf{KMnO}_4$) and Potassium Dichromate ($\textsf{K}_2\textsf{Cr}_2\textsf{O}_7$) are studied. The **Lanthanoid contraction** and its consequences are explained, highlighting the unique characteristics and uses of these elements, which are often found in various alloys and catalysts.
9. Coordination Compounds
This chapter introduces **coordination compounds** or complexes, containing a central metal atom or ion bonded to ligands via coordinate covalent bonds. It discusses **Werner's theory**, defines key terms like coordination number, ligands (monodentate, polydentate), chelation, and oxidation state. The **IUPAC nomenclature** system for naming these compounds is covered. Different types of **isomerism** (structural and stereoisomerism) are discussed. Bonding theories, including Valence Bond Theory (VBT) and **Crystal Field Theory (CFT)**, are used to explain their structure, bonding, magnetic properties, and colour. Their applications in various fields, including biological systems (e.g., chlorophyll, haemoglobin) and industry, are also highlighted.
10. Haloalkanes And Haloarenes
This chapter deals with organic compounds containing halogen atoms attached to alkyl groups (**haloalkanes**) or aryl groups (**haloarenes**). It covers their nomenclature, classification, and methods of preparation (e.g., from alcohols, hydrocarbons). Physical properties (boiling points, solubility) and important **chemical reactions** are discussed. For haloalkanes, **nucleophilic substitution reactions** ($\textsf{S}_\text{N}1$ and $\textsf{S}_\text{N}2$ mechanisms) and elimination reactions are key. Preparation and **electrophilic substitution reactions** of haloarenes are explained, highlighting the difference in reactivity compared to haloalkanes. The chapter also briefly mentions the uses and environmental effects of some polyhalogen compounds.
11. Alcohols, Phenols And Ethers
This chapter explores the chemistry of organic compounds containing the hydroxyl functional group (-OH) – **alcohols** (in aliphatic compounds) and **phenols** (in aromatic compounds) – and the ether linkage (-O-), **ethers**. It covers their nomenclature, methods of preparation (e.g., from alkenes, carbonyl compounds), physical properties (influenced by hydrogen bonding in alcohols/phenols), and characteristic chemical reactions. The **acidic nature** of alcohols and phenols is compared. Reactions like esterification, oxidation, dehydration, and electrophilic substitution (for phenols) are discussed. Preparation and reactions of ethers, including cleavage reactions and electrophilic substitution (for aromatic ethers), are also studied, highlighting the diverse reactions of these oxygen-containing functional groups.
12. Aldehydes, Ketones And Carboxylic Acids
This chapter focuses on organic compounds containing the **carbonyl group** ($\textsf{C=O}$) – **aldehydes** and **ketones** – and the **carboxyl group** ($\textsf{-COOH}$) – **carboxylic acids**. It covers their nomenclature, structure, methods of preparation (e.g., oxidation of alcohols, ozonolysis), physical properties, and distinctive chemical reactions. Key reactions for aldehydes and ketones include **nucleophilic addition**, oxidation, reduction, **Aldol condensation**, and **Cannizzaro reaction**. For carboxylic acids, the **acidic nature** is discussed, along with reactions like esterification, reduction, and reactions involving the $\alpha$-hydrogen (**HVZ reaction**). Uses of these compound families are highlighted.
13. Amines
**Amines** are organic compounds containing nitrogen, derived from ammonia ($\textsf{NH}_3$) by replacing one or more hydrogen atoms with alkyl or aryl groups. This chapter covers their nomenclature, classification (primary $1^\circ$, secondary $2^\circ$, tertiary $3^\circ$), and methods of preparation (e.g., reduction of nitro compounds, ammonolysis of alkyl halides, Gabriel phthalimide synthesis, Hoffmann bromamide degradation). Their physical properties (like boiling points, basic strength) and important chemical reactions are discussed. A key aspect is their **basic nature** ($\textsf{K}_\text{b}$ values) and reactions like alkylation, acylation, reactions with nitrous acid, and the **Hinsberg test** for distinguishing primary, secondary, and tertiary amines. Reactions involving **diazonium salts** are also introduced, significant in organic synthesis.
14. Biomolecules
This chapter focuses on the essential organic molecules found in living organisms, crucial for biological processes. It covers the structure and function of the four major classes of **biomolecules**: **Carbohydrates** (energy sources, structure - e.g., glucose, sucrose, starch, cellulose), **Proteins** (polymers of amino acids, diverse functions - enzymes, antibodies, structure), **Nucleic Acids** (DNA and RNA - carriers of genetic information), and **Lipids** (fats, phospholipids, steroids). The chapter also discusses the role of **Enzymes** as biological catalysts, introduces **Vitamins** and **Hormones**, highlighting the complex interplay of these molecules in sustaining life and metabolism.
15. Polymers
This chapter introduces **polymers**, large macromolecules formed by the repetitive joining of small molecular units called monomers. It covers their classification based on source (natural, synthetic, semi-synthetic), structure (linear, branched, cross-linked), mode of polymerization (**addition** and **condensation polymerization**), and molecular forces (elastomers, fibres, thermoplastics, thermosetting plastics). Different types of polymerization mechanisms are discussed. The structure, properties, and uses of important synthetic polymers like polyethylene, PVC, Teflon, nylon, Bakelite, rubber (natural and synthetic) are explained. Biodegradable polymers and their importance are also mentioned, relevant in environmental context.
16. Chemistry In Everyday Life
This chapter explores the application of chemical principles and compounds in various aspects of our daily lives. It discusses the chemistry of **drugs**, classifying them based on pharmacological action (e.g., analgesics, antipyretics, antacids, tranquillizers, antiseptics, disinfectants, antibiotics). The chemistry of **food** additives like preservatives, artificial sweetening agents, and antioxidants is explained. The chapter also covers **cleansing agents**, detailing the structure and action of soaps and synthetic detergents, highlighting their differences and uses in cleaning. Understanding this helps appreciate how chemical principles are used in common products we interact with daily.