Here is a summary note for MCQ preparation for the lesson:
“General and Language of Chemistry”
(Covers: Atoms, Ions, Molecules, Elements, Compounds, Radicals, Valency, Commercial names of compounds, Types of Chemical Reaction, Methods of Mixture Separation)
1. Atom, Molecule, Ion
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Atom: The smallest unit of an element that retains its properties. Eg: H, O, Na.
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Molecule: A Combination of two or more atoms (same or different). Eg: O₂, H₂O.
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Ion: Charged particles.
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Cation: Positively charged (Na⁺, Ca²⁺)
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Anion: Negatively charged (Cl⁻, SO₄²⁻)
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2. Element and Compound
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Element: Pure substance made of only one type of atom. Eg: Iron (Fe), Oxygen (O₂).
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Compound: Substance formed by the chemical combination of two or more elements in a fixed proportion. Eg: H₂O, NaCl.
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Molecule of Element: O₂, H₂
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Molecule of Compound: CO₂, NH₃
3. Radical and Valency
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Radical: A Group of atoms that behaves like a single atom in chemical reactions. Can be positive or negative.
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Eg: OH⁻, SO₄²⁻, NH₄⁺
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Valency: The Combining capacity of an atom or radical.
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Eg: H (1), O (2), N (3), C (4), SO₄ (2), Cl (1)
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4. Naming Compounds (Commercial Names)
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H₂O – Water
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NaCl – Table salt
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CaCO₃ – Limestone/Marble/Chalk
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NaHCO₃ – Baking soda
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Ca(OH)₂ – Lime water
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Na₂CO₃ – Washing soda
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HCl – Hydrochloric acid (muriatic acid)
5. Types of Chemical Reactions
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Combination Reaction: A + B → AB
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Decomposition Reaction: AB → A + B
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Displacement Reaction: A + BC → AC + B
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Double Displacement Reaction: AB + CD → AD + CB
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Neutralization: Acid + Base → Salt + Water
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Combustion: Fuel + O₂ → CO₂ + H₂O + Heat
6. Methods of Separation of Mixtures
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Evaporation: For salt from saltwater
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Filtration: Insoluble solids from liquids
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Distillation: Separating two miscible liquids
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Decantation: Solid-liquid separation after sedimentation
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Centrifugation: Fine solid particles from liquid
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Sublimation: Separating a solid that sublimes (e.g., camphor, iodine)
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Chromatography: Separation of different dyes/pigments
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Magnetic Separation: Iron from a mixture
🧠 Tips for MCQs:
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Know the symbols and formulas well.
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Be clear about valency rules and how to write chemical formulas.
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Identify radicals and their charges quickly.
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Remember the types and examples of chemical reactions.
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Understand practical methods of separation with suitable examples.