πŸ” General and Language of Chemistry: Summary Note for MCQ

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

  • Atom: The smallest unit of an element that retains its properties. Eg: H, O, Na.

  • Molecule: A Combination of two or more atoms (same or different). Eg: Oβ‚‚, Hβ‚‚O.

  • Ion: Charged particles.

    • Cation: Positively charged (Na⁺, Ca²⁺)

    • Anion: Negatively charged (Cl⁻, SO₄²⁻)

2. Element and Compound

  • Element: Pure substance made of only one type of atom. Eg: Iron (Fe), Oxygen (Oβ‚‚).

  • Compound: Substance formed by the chemical combination of two or more elements in a fixed proportion. Eg: Hβ‚‚O, NaCl.

  • Molecule of Element: Oβ‚‚, Hβ‚‚

  • Molecule of Compound: COβ‚‚, NH₃

3. Radical and Valency

  • Radical: A Group of atoms that behaves like a single atom in chemical reactions. Can be positive or negative.

    • Eg: OH⁻, SO₄²⁻, NH₄⁺

  • Valency: The Combining capacity of an atom or radical.

    • Eg: H (1), O (2), N (3), C (4), SOβ‚„ (2), Cl (1)

4. Naming Compounds (Commercial Names)

  • Hβ‚‚O – Water

  • NaCl – Table salt

  • CaCO₃ – Limestone/Marble/Chalk

  • NaHCO₃ – Baking soda

  • Ca(OH)β‚‚ – Lime water

  • Naβ‚‚CO₃ – Washing soda

  • HCl – Hydrochloric acid (muriatic acid)

5. Types of Chemical Reactions

  • Combination Reaction: A + B β†’ AB

  • Decomposition Reaction: AB β†’ A + B

  • Displacement Reaction: A + BC β†’ AC + B

  • Double Displacement Reaction: AB + CD β†’ AD + CB

  • Neutralization: Acid + Base β†’ Salt + Water

  • Combustion: Fuel + Oβ‚‚ β†’ COβ‚‚ + Hβ‚‚O + Heat

6. Methods of Separation of Mixtures

  • Evaporation: For salt from saltwater

  • Filtration: Insoluble solids from liquids

  • Distillation: Separating two miscible liquids

  • Decantation: Solid-liquid separation after sedimentation

  • Centrifugation: Fine solid particles from liquid

  • Sublimation: Separating a solid that sublimes (e.g., camphor, iodine)

  • Chromatography: Separation of different dyes/pigments

  • Magnetic Separation: Iron from a mixture

🧠 Tips for MCQs:

  • Know the symbols and formulas well.

  • Be clear about valency rules and how to write chemical formulas.

  • Identify radicals and their charges quickly.

  • Remember the types and examples of chemical reactions.

  • Understand practical methods of separation with suitable examples.

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