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| Classwise Science MCQ Questions with Solutions (Class 11th) | ||||||||||||||
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| Classwise Science MCQ Questions with Solutions (Class 12th) | ||||||||||||||
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Class 11th Chemistry MCQ Questions
1. Some Basic Concepts Of Chemistry
This chapter introduces the fundamental concepts of chemistry, the science of matter and its transformations. It covers the classification of matter, properties, and units of measurement (SI Units). Key concepts include the **Laws of Chemical Combination** (e.g., Law of Conservation of Mass), Dalton's Atomic Theory, and the concepts of atoms, molecules, and ions. Crucially, the **mole concept** ($\textsf{1 mole} = 6.022 \times 10^{23}$ particles) and molar mass are explained, enabling quantitative calculations in chemistry, such as stoichiometry and expressing solution concentrations (e.g., molarity $\textsf{M}$), providing a basis for all chemical studies.
2. Structure Of Atom
This chapter explores the internal structure of the atom, building upon earlier simple models. It details the discovery of **subatomic particles** (electrons, protons, neutrons) and the evolution of atomic models from Thomson and Rutherford to **Bohr's model** for the hydrogen atom explaining spectral lines. The wave-particle duality of matter (De Broglie's hypothesis $\lambda = \frac{\textsf{h}}{\textsf{p}}$) and the uncertainty principle are introduced. The chapter explains atomic orbitals using **quantum numbers** and describes how electrons are filled in orbitals following rules like the Aufbau principle, Hund's rule, and Pauli exclusion principle, providing a quantum mechanical understanding of atomic structure.
3. Classification Of Elements And Periodicity In Properties
This chapter explains how elements are systematically organized in the **Periodic Table**, reflecting their properties and chemical behaviour. It discusses the historical development of classification systems, highlighting the contributions of Mendeleev and his Periodic Law. The **Modern Periodic Table**, based on the atomic number, is presented, explaining the arrangement of elements into periods and groups. The **periodicity of properties** such as atomic size, ionic size, ionisation enthalpy, electron gain enthalpy, and electronegativity is discussed, showing predictable trends across periods and down groups, which helps in understanding chemical properties of elements.
4. Chemical Bonding And Molecular Structure
This crucial chapter explores how atoms combine to form molecules and the forces holding them together (**chemical bonds**). It covers different types of bonds: **ionic bonds** (electron transfer), **covalent bonds** (electron sharing), and coordinate bonds. Concepts like **Lewis structures**, formal charge, bond parameters, resonance, and polarity are discussed. Bonding theories like **VSEPR Theory** for predicting molecular shapes, **Valence Bond Theory (VBT)** explaining hybridization and orbital overlap, and **Molecular Orbital Theory (MOT)** are introduced to understand molecular structure and bonding. Intermolecular forces (Van der Waals, hydrogen bonding) are also covered, influencing physical properties.
5. States Of Matter
This chapter discusses the three physical states of matter – solid, liquid, and gas – and the role of **intermolecular forces** in determining these states. It focuses particularly on the **gaseous state**, explaining the **gas laws** (Boyle's Law $\textsf{PV = constant}$, Charles's Law $\frac{\textsf{V}}{\textsf{T}} = \textsf{constant}$) and the **Ideal Gas Equation** ($\textsf{PV = nRT}$). Dalton's law of partial pressures and Graham's law of diffusion are covered. The chapter introduces the **Kinetic Theory of Gases** to explain gas behaviour from a molecular perspective and discusses the properties of liquids like vapour pressure, viscosity, and surface tension.
6. Thermodynamics
**Thermodynamics** is the branch of chemistry that deals with energy changes during physical and chemical processes. This chapter introduces fundamental concepts like system, surroundings, state functions. The **First Law of Thermodynamics** ($\Delta \textsf{U} = \textsf{Q} + \textsf{W}$), a statement of energy conservation, and the concept of **enthalpy** ($\Delta \textsf{H}$) are central. Thermochemistry, including enthalpy of formation, combustion, and bond enthalpy, and **Hess's Law** are covered. The **Second Law of Thermodynamics** introduces **entropy** ($\Delta \textsf{S}$) and the spontaneity of processes. **Gibbs Free Energy** ($\Delta \textsf{G} = \Delta \textsf{H} - \textsf{T}\Delta \textsf{S}$) is used to predict spontaneity and relates to equilibrium.
7. Equilibrium
This chapter focuses on the state of **equilibrium** in reversible processes, both physical and chemical, where the forward and reverse rates are equal. It covers **chemical equilibrium**, introducing the **Law of Mass Action** and the **equilibrium constant** ($\textsf{K}_\text{c}$ and $\textsf{K}_\text{p}$), which indicates the extent of a reaction. **Le Chatelier's principle** is explained to predict the effect of changes in concentration, temperature, or pressure on the equilibrium position. **Ionic equilibrium** discusses acid-base theories, the pH scale ($\textsf{pH} = -\textsf{log}[\textsf{H}^+]$), hydrolysis of salts, buffer solutions, solubility product, and the common ion effect.
8. Redox Reactions
**Redox reactions** involve simultaneous **oxidation** and **reduction**, fundamentally representing the transfer of electrons. This chapter defines oxidation and reduction in terms of electron transfer and changes in **oxidation numbers**. Rules for assigning oxidation numbers are provided. Various types of redox reactions are discussed. A key skill taught is the **balancing of redox reactions** using methods like the oxidation number method and the ion-electron method. The chapter also introduces the concept of electrochemical cells (Galvanic cells and Electrolytic cells) where redox reactions are utilized to produce or consume electrical energy, linking chemistry and electricity.
9. Hydrogen
This chapter is dedicated to the element **hydrogen**, the lightest element with unique properties and position in the periodic table. It discusses isotopes of hydrogen (protium, deuterium, tritium), methods of preparation (laboratory and industrial), and its physical and chemical properties. Compounds of hydrogen, such as water (its structure and properties) and hydrogen peroxide ($\textsf{H}_2\textsf{O}_2$), are covered. Different types of hydrides (ionic, covalent, metallic) are explained. The chapter highlights the uses of hydrogen and its potential as a future fuel, particularly relevant for sustainable energy discussions in India.
10. The S-Block Elements
This chapter focuses on the chemistry of the **s-block elements**, which include Alkali Metals (Group 1) and Alkaline Earth Metals (Group 2). Their electronic configurations and general characteristics, such as atomic and ionic radii, ionization enthalpy, hydration enthalpy, and metallic nature, are discussed, showing trends within the groups. The methods of preparation, physical and chemical properties, and uses of important compounds of these elements (e.g., $\textsf{NaOH}$, $\textsf{Na}_2\textsf{CO}_3$, $\textsf{CaO}$, $\textsf{CaCO}_3$) are explained. The chapter highlights the anomalous behaviour of the first element of each group and diagonal relationships.
11. The P-Block Elements
This chapter provides an introduction to the **p-block elements**, located in groups 13 to 18 of the periodic table, excluding Helium. It discusses their general electronic configuration and trends in properties. The chemistry of specific groups is explored, focusing on Boron family (Group 13) and Carbon family (Group 14). Important compounds of Boron (e.g., borax, boric acid, diborane) and Carbon (e.g., oxides of carbon, silicon compounds like silicates, zeolites) are discussed. The chapter highlights the anomalous behaviour of the first element of each group and diagonal relationships.
12. Organic Chemistry: Some Basic Principles And Techniques
This chapter serves as an essential foundation for **organic chemistry**, the study of carbon compounds. It explains the unique bonding nature of carbon (tetravalency, catenation) and introduces the classification and **IUPAC nomenclature** of organic compounds. Concepts like isomerism, types of chemical reactions, bond cleavage (homolytic, heterolytic), reactive intermediates (carbocations, carbanions, free radicals), and electronic effects (inductive, resonance, hyperconjugation) influencing reactivity are discussed, along with methods for purification and analysis of organic compounds, providing fundamental knowledge and practical techniques for the study of carbon compounds.
13. Hydrocarbons
This chapter focuses on **hydrocarbons**, organic compounds containing only carbon and hydrogen. They are classified into saturated (**alkanes**) and unsaturated (**alkenes**, **alkynes**) aliphatic hydrocarbons, and aromatic hydrocarbons. The nomenclature, isomerism, methods of preparation, physical properties, and important chemical reactions (like substitution in alkanes, addition in alkenes/alkynes, combustion, pyrolysis) are discussed for each class. The special stability and structure of **benzene**, the simplest aromatic hydrocarbon, and the concept of aromaticity are also explained, providing a fundamental understanding of these essential organic families which are key components of fuels and many organic products.
14. Environmental Chemistry
This chapter addresses the chemical processes occurring in the environment and the impact of human activities, focusing on **environmental pollution**. It discusses pollution of the atmosphere, hydrosphere, and lithosphere, identifying major pollutants and their sources (e.g., industrial emissions, vehicular exhaust, pesticides). Concepts like **acid rain**, **ozone layer depletion**, **greenhouse effect**, and **global warming** are explained from a chemical perspective. Strategies for controlling environmental pollution and the importance of **green chemistry** for designing environmentally friendly processes are highlighted, linking chemistry to real-world environmental issues and sustainability, a significant challenge in India and globally.