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What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer.
(i) Hydrogen gas and Iron chloride are produced.
(ii) Chlorine gas and Iron hydroxide are produced.
(iii) No reaction takes place.
(iv) Iron salt and water are produced.

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Hydrogen gas and Iron chloride are produced. The iron fillings displace the chlorine from hydrogen chloride to cause the reaction that follows. 2HCl + Fe → FeCl2 + H2

Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a (i)Combination reaction (ii)Double displacement reaction (iii)Decomposition reaction (iv)Displacement reaction

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The answer is (iv). Displacement reaction. Reason: To create Aluminium oxide, oxygen from ferrous oxide is transferred to Aluminium metal. Aluminium is a more reactive metal than Fe in this reaction. Al will therefore remove Fe from its oxide. One of the elements displaces another in a chemical process known as a displacement reaction. More …

Fe2O3 + 2Al → Al2O3 + 2Fe The above reaction is an example of a (i)Combination reaction (ii)Double displacement reaction (iii)Decomposition reaction (iv)Displacement reaction Read More »

Which of the statements about the reaction below are incorrect? 2PbO(s) + C(s) → 2Pb(s) + CO2(g) (a) Lead is getting reduced (b) Carbon Dioxide is getting oxidised (c) Carbon is getting oxidised (d) Lead oxide is getting reduced (i) (a) and (b) (ii) (a) and (c) (iii) (a), (b) and (c) (iv) all the above

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(i) (a) and (b) Explanation: (a) Because oxygen is being taken out, and (b) Because the elemental Carbon is being given more oxygen taken out of Lead.

Identify the substances that are oxidised and that are reduced in the following equation.
(i) 4Na(s) + O2(g) → 2Na2O(s)
(ii) CuO(s) + H2(g) → Cu(s) + H2O(l)

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With the addition of oxygen (O2) in the first equation, the sodium (Na) becomes oxidised, and the reduction of copper (Cu) in the second equation results from the addition of hydrogen (H2).

. Give an example of a double displacement reaction other than the one given in Activity 1.10.

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Reaction A double displacement reaction can be seen between sodium chloride (NaCl) and silver nitrate (AgNO3). Due to the production of a white silver chloride precipitate, positive and negative ions exchange positions during the reaction. The chemical is explained below : Ag+ + NO3– + Na+ + Cl– → AgCl + Na+ + NO3–

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

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Because iron is more reactive than copper, it displaces copper from the copper sulphate solution when an iron nail is dipped in the solution. As a result, the copper sulphate solution\’s colour changes from blue to green. The result is CuSO4 ( Blue) + Fe → FeSO4 (Green) + Cu

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

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Because water gets hydrolyzed to produce H2 and O2 gas in activity 1.7, the amount of gas collected in one of the test tubes is double that of the other. Here, two molecules of hydrogen and one molecule of oxygen are released as a result of electrolysis; as a result, there will be twice as …

Why is the amount of gas collected in one of the test tubes in Activity 1.7 double the amount collected in the other? Name this gas. Read More »

A solution of a substance, ‘X,’ is used for whitewashing.
(i) Name the substance ‘X’ and write its formula.
(ii) Write the reaction of the substance ‘X’ named in (i) above with water.

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(i) The substance ‘X’ which is used in whitewashing is quick lime or Calcium Oxide and its formula is CaO. (ii) CaO + H2O → Ca(OH)2

Write a balanced chemical equation with state symbols for the following reactions (i) Solutions of Barium chloride and Sodium sulphate in water react to give insoluble Barium sulphate and solution of Sodium chloride. (ii) Sodium hydroxide solution in water reacts with the hydrochloric acid solution to produce Sodium chloride solution and water.

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(i) BaCl2 + Na2SO4 → BaSO4 + 2NaCl (ii) NaOH + HCl → NaCl + H2O

Write a balanced equation for the following chemical reactions. i) Hydrogen + Chloride —-> Hydrogen chloride ii) Barium chloride + Aluminium sulphate —-> Barium sulphate + Aluminium chloride iii) Sodium + Water —-> Sodium hydroxide + Hydrogen

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i) H2 + Cl2 → 2HCl ii) 3BaCl2 + Al2(SO4)3 →3BaSO4 + 2AlCl3 iii) 2Na + 2H2O → 2NaOH + H2