Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a

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    Displacement Reaction Example

    Fe2O3 + 2Al → Al2O3 + 2Fe

    The above reaction is an example of a:

    1. (a) Combination reaction
    2. (b) Double displacement reaction
    3. (c) Decomposition reaction
    4. (d) Displacement reaction

    Answer: (d) The given reaction is an example of a displacement reaction.

    Explanation: In the reaction, aluminum (Al) displaces iron (Fe) from iron oxide (Fe₂O₃), which is characteristic of a displacement reaction. Displacement reactions occur when one element displaces another from a compound.

    Chemical Reaction:

    Fe2O3 (s) + 2 Al (s) → Al2O3 (s) + 2 Fe (s)

    Which of the statements about the reaction below are incorrect?

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      Oxidation and Reduction Reactions

      Which of the statements about the reaction below are incorrect?

      Chemical Reaction:

      2PbO (s) + C (s) → 2Pb (s) + CO2 (g)

      Answer: (i) (a) and (b)

      Statements:

      1. (a) Lead is getting reduced.
      2. (b) Carbon dioxide is getting oxidised.
      3. (c) Carbon is getting oxidised.
      4. (d) Lead oxide is getting reduced.

      Select the correct option:

      1. (i) (a) and (b)
      2. (ii) (a) and (c)
      3. (iii) (a), (b) and (c)
      4. (iv) All

      Identification of Oxidation and Reduction in Reactions

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        Oxidation and Reduction Reactions

        Identification of Oxidation and Reduction in Reactions

        (i) Oxidation and Reduction in the Reaction

        Answer: In this reaction, sodium (Na) is oxidized as it gains oxygen, and oxygen (O2) is reduced by gaining electrons.

        Chemical Reaction:

        2 Na (s) + O2 (g) → 2 Na2O (s)

        (ii) Oxidation and Reduction in the Reaction

        Answer: In this reaction, copper oxide (CuO) is reduced to copper (Cu), while hydrogen (H2) gets oxidized to form water (H2O).

        Chemical Reaction:

        CuO (s) + H2 (g) → Cu (s) + H2O (l)

        Example of a Double Displacement Reaction

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          Double Displacement Reaction Example

          Example of a Double Displacement Reaction

          Answer:

          Sodium carbonate reacts with calcium chloride to form calcium carbonate and sodium chloride. In this reaction, sodium carbonate and calcium chloride exchange ions to form two new compounds. Hence, it is a double displacement reaction.

          Chemical Reaction:

          Na2CO3 (aq) + CaCl2 (aq) → CaCO3 (s) + 2 NaCl (aq)

          Why Does the Colour of Copper Sulphate Solution Change When an Iron Nail is Dipped in It?

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            Displacement Reaction of Copper Sulphate and Iron Nail

            Why Does the Colour of Copper Sulphate Solution Change When an Iron Nail is Dipped in It?

            Explanation of the Chemical Reaction:

            When an iron nail is placed in a copper sulfate solution, a chemical displacement reaction occurs. During this reaction, iron displaces copper from the copper sulfate solution.

            Displacement Reaction:

            The iron nail reacts with the copper sulfate (CuSO4) to form iron sulfate (FeSO4) and free copper metal. This reaction is represented by the following equation:

            Fe + CuSO₄ → FeSO₄ + Cu

            As a result, the blue colour of the copper sulfate solution fades, and a green colour appears due to the formation of iron sulfate, which is green in colour.

            Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other?

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              Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other?

              Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other?

              Name this gas.

              Answer:

              Water (H2O) contains two parts hydrogen and one part oxygen. Therefore, the amount of hydrogen and oxygen produced during electrolysis of water is in a 2:1 ratio. During electrolysis, since hydrogen goes to one test tube and oxygen goes to another, the amount of gas collected in one of the test tubes is double of the amount collected in the other.

              The gas collected in the test tube containing the larger amount is hydrogen gas (H2).

              A solution of a substance ‘X’ is used for white washing.

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                White Washing Substance

                A solution of a substance ‘X’ is used for white washing.

                i) Name the substance ‘X’ and write its formula.

                ii) Write the reaction of the substance ‘X’ named in (i) above with water.

                Answer:

                i) The substance ‘X’ is calcium oxide. Its chemical formula is CaO.

                ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime) as shown below:

                CaO + H2O → Ca(OH)2

                Write a balanced chemical equation with state symbols for the following reactions

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                Question: Write a balanced chemical equation with state symbols for the following reactions.

                1. Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
                2. Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

                Answer:

                1. BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)
                2. NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

                Write the balanced equation for the following chemical reactions.

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                  Question 2: Write the balanced equation for the following chemical reactions.

                  1. Hydrogen + Chlorine → Hydrogen chloride
                  2. Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
                  3. Sodium + Water → Sodium hydroxide + Hydrogen

                  Answer:

                  1. 2H2 + Cl2 → 2HCl
                  2. BaCl2 + Al2(SO4)3 → BaSO4 + 2AlCl3
                  3. 2Na + 2H2O → 2NaOH + H2

                  Why should a magnesium ribbon be cleaned before burning in air?

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                  Why should a magnesium ribbon be cleaned before burning in air?

                  Magnesium is a very reactive metal. When stored, it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sandpaper to remove this layer so that the underlying metal can be exposed to air.