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Topic 7 Practice Paper: Acids, bases and salts — question paper

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QQ/IGCSE-CHEM/T7

IGCSE · Cambridge IGCSE Chemistry (Extended (Core + Supplement))

Topic 7 Practice Paper

Acids, bases and salts

Duration: 40 minutes
Total: 30 marks
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READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A contains ten multiple-choice questions. Choose one answer, A, B, C or D, for each.
  • Section B contains structured questions. Write your answers in the spaces provided.
  • The number of marks is given in brackets [ ] at the end of each question or part question.
  • The total mark for this paper is 30.

Original practice material written against the Cambridge IGCSE Chemistry syllabus. It is not an official Cambridge examination paper. Topic 7: Acids, bases and salts.

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

  1. 1

    Which substance dissolves in water to give an alkaline solution?

    1. AAqueous ammonia
    2. BCopper(II) oxide
    3. CSulfur dioxide
    4. DEthanoic acid
    ( )
  2. 2

    Methyl orange is added to a solution of pH 3. What colour is seen?

    1. AYellow
    2. BBlue
    3. CRed
    4. DColourless
    ( )
  3. 3

    Which equation for the reaction of calcium carbonate with excess dilute hydrochloric acid is correct?

    1. A2HCl + CaCO₃ → CaCl₂ + H₂O + H₂
    2. B2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂
    3. CHCl + CaCO₃ → CaCl + H₂O + CO₂
    4. D2HCl + CaCO₃ → CaCl₂ + 2H₂O
    ( )
  4. 4

    Universal indicator paper is dipped into a neutral solution. Which colour is shown?

    1. ARed
    2. BPurple
    3. CBlue
    4. DGreen
    ( )
  5. 5

    Copper(II) carbonate is warmed with dilute nitric acid until no more solid reacts. The solid removed by filtration is

    1. Acopper(II) nitrate
    2. Bcarbon dioxide
    3. Cwater
    4. Dcopper(II) carbonate
    ( )
  6. 6

    Solutions of four acids all have the same concentration. Which has the highest pH?

    1. AHydrochloric acid
    2. BEthanoic acid
    3. CSulfuric acid
    4. DNitric acid
    ( )
  7. 7

    Excess magnesium ribbon is stirred with dilute sulfuric acid and the mixture is filtered. What is left on the filter paper?

    1. AMagnesium sulfate solution
    2. BHydrogen
    3. CMagnesium
    4. DWater
    ( )
  8. 8

    Which pair of salts are both soluble in water?

    1. ALead chloride and silver chloride
    2. BSodium carbonate and ammonium nitrate
    3. CBarium sulfate and calcium sulfate
    4. DCopper(II) carbonate and zinc carbonate
    ( )
  9. 9

    Blue crystals of formula CuSO₄•5H₂O are heated gently. Which change is observed?

    1. AThe crystals turn white and lose water
    2. BThe crystals dissolve
    3. CThe crystals turn green and give off oxygen
    4. DThe crystals melt and burn
    ( )
  10. 10

    Which reagent pair is suitable for preparing lead chloride by precipitation?

    1. AAqueous lead nitrate and dilute hydrochloric acid
    2. BLead metal and dilute sulfuric acid
    3. CAqueous sodium chloride and aqueous potassium nitrate
    4. DLead oxide and aqueous sodium chloride
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 11

    A gardener finds that the soil in a field has a pH of 4.5, which is too acidic for the crop being grown.

    1. (a)

      Name one substance the gardener could add to raise the pH of the soil.

      [1]
    2. (b)

      Explain, in terms of ions, why adding this substance raises the pH.

      [2]
    3. (c)

      State the pH value that corresponds to a neutral soil.

      [1]
  2. 12

    A fertiliser factory makes ammonium sulfate, a nitrogen-rich fertiliser, by reacting ammonia solution with dilute sulfuric acid.

    1. (a)

      Name the type of reaction between an acid and an alkali.

      [1]
    2. (b)

      Both reactants are soluble. Explain why a titration is carried out before the salt is made.

      [2]
    3. (c)

      Explain why the final solution is concentrated and left to crystallise rather than being evaporated to complete dryness.

      [2]
  3. 13

    Barium sulfate is an insoluble salt used in medical X-ray imaging of the digestive system.

    1. (a)

      Name two aqueous solutions that could be mixed to precipitate barium sulfate.

      [2]
    2. (b)

      Describe how a pure, dry sample of barium sulfate is obtained after the two solutions are mixed.

      [3]
  4. 14

    Solution X contains one cation and one anion. Tests on separate portions of X give the results in the table.

    Test results for solution X

    TestObservation
    Add aqueous sodium hydroxide drop by drop, then in excessWhite precipitate forms, which dissolves in excess to give a colourless solution
    Add aqueous ammonia drop by drop, then in excessWhite precipitate forms, which dissolves in excess to give a colourless solution
    Add dilute nitric acid, then aqueous silver nitrateWhite precipitate forms
    1. (a)

      Identify the cation in X and explain how the tests identify it.

      [2]
    2. (b)

      Identify the anion in X.

      [1]
    3. (c)

      Write the ionic equation, including state symbols, for the reaction in the third test.

      [2]
    4. (d)

      Name the solution formed when the white precipitate in the first test dissolves in excess.

      [1]

— End of paper —