1. Ionic compounds are formed by strong electrostatic forces of attraction between the ions. So, it requires a lot of energy to overcome these forces. So ionic compounds have high melting points.

    Ionic compounds are formed by strong electrostatic forces of attraction between the ions. So, it requires a lot of energy to overcome these forces. So ionic compounds have high melting points.

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  2. Hydrochloric acid when added to a reactive metal like sodium, potassium etc. Hydrogen gas is evolved. When iron metal reacts with dilute H2SO4, iron sulphate is formed with the evolution of hydrogen gas.

    Hydrochloric acid when added to a reactive metal like sodium, potassium etc.
    Hydrogen gas is evolved.

    When iron metal reacts with dilute H2SO4, iron sulphate is formed with the evolution of hydrogen gas.

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  3. Zinc is more reactive than iron. Therefore, when zinc is added to a solution of iron (II) sulphate, then it would displace iron from the solution. Zn + FeSO4  →  ZnSO4 + Fe

    Zinc is more reactive than iron. Therefore, when zinc is added to a solution of iron (II) sulphate, then it would displace iron from the solution.

    Zn + FeSO4  →  ZnSO4 + Fe

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  4. (i) Iron reacts to steam to form ferrous oxide and hydrogen gas. 3Fe(s) + 4H₂O(g) → Fe3O4(s) + 4H₂(g) (ii) Calcium reacts with water and forms calcium hydroxide commonly known as slaked lime. Ca(s) + 2H₂O(l) → Ca(OH) ₂ (aq) + H₂ (g) 2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) + heat energy

    (i) Iron reacts to steam to form ferrous oxide and hydrogen gas.

    3Fe(s) + 4H₂O(g) → Fe3O4(s) + 4H₂(g)

    (ii) Calcium reacts with water and forms calcium hydroxide commonly known as slaked lime.

    Ca(s) + 2H₂O(l) → Ca(OH) ₂ (aq) + H₂ (g)

    2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) + heat energy

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  5. Sodium is highly reactive metal so it  combines with air as well as water to form sodium oxide and hydrogen gas with heat energy.this heat is sufficient to burn hydrogen gas. That's why it catches fire if kept in open. Therefore, to prevent  sodium from combining with air and accidental fires, sodiuRead more

    Sodium is highly reactive metal so it  combines with air as well as water to form sodium oxide and hydrogen gas with heat energy.this heat is sufficient to burn hydrogen gas. That’s why it catches fire if kept in open. Therefore, to prevent  sodium from combining with air and accidental fires, sodium is stored in kerosene oil.

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