1. (i) When Zinc carbonate is calcined : ZnCo₃ ⟶ ZnO + CO₂↑ (ii) When manganese dioxide is heated with aluminum powder: 3MnO₂ + 4A1 ⟶ 3Mn + 2A1₂O₃ (iii) When magnesium is heated with very dil. HNO₃: Mg + 2HNO₃ ⟶ Mg(NO₃)₂ + H₂

    (i) When Zinc carbonate is calcined :
    ZnCo₃ ⟶ ZnO + CO₂↑
    (ii) When manganese dioxide is heated with aluminum powder:
    3MnO₂ + 4A1 ⟶ 3Mn + 2A1₂O₃
    (iii) When magnesium is heated with very dil. HNO₃:
    Mg + 2HNO₃ ⟶ Mg(NO₃)₂ + H₂

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  2. (i) Phenolphthalein gives a pink colour with soap because soap contains alkali in traces. (ii) By-products of chlor-alkali Process: NaOH, H ₂ and C1₂ (iii) Universal indicator specifies the various levels of H+ concentration.

    (i) Phenolphthalein gives a pink colour with soap because soap contains alkali in traces.
    (ii) By-products of chlor-alkali Process:
    NaOH, H ₂ and C1₂
    (iii) Universal indicator specifies the various levels of H+ concentration.

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  3. Quicklime reacts with water to form slaked lime (lime water). It is an exothermic reaction. That is why the container became hot. CaO + 2H₂O ⟶ Ca(OH)₂ + Heat When calcium hydroxide is applied on the wails, it reacts with atmospheric carbon dioxide to form calcium carbonate which gives a shining whitRead more

    Quicklime reacts with water to form slaked lime (lime water). It is an exothermic reaction. That is why the container became hot.
    CaO + 2H₂O ⟶ Ca(OH)₂ + Heat
    When calcium hydroxide is applied on the wails, it reacts with atmospheric carbon dioxide to form calcium carbonate which gives a shining white coating on the walls.
    Ca(OH) ₂ + CO₂ ⟶ CaCO₃ + H₂O

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  4. Chemical name for baking soda is sodium hydrogencarbonate and its formula is NaHCO₃. Preparation of baking soda: NaC1 + H₂O + CO₂ + NH₃ ⟶ NH₄C1 + NaHCO₃

    Chemical name for baking soda is sodium hydrogencarbonate and its formula is NaHCO₃.
    Preparation of baking soda:
    NaC1 + H₂O + CO₂ + NH₃ ⟶ NH₄C1 + NaHCO₃

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  5. (i) 2A1 + 3H₂O (steam) ⟶ A1₂O₃ + 3H₂ (ii) Ca + 2H₂O ⟶ Ca(OH)₂ + H₂

    (i) 2A1 + 3H₂O (steam) ⟶ A1₂O₃ + 3H₂
    (ii) Ca + 2H₂O ⟶ Ca(OH)₂ + H₂

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