IGCSEChemistryCambridge (CIE)Exam Questions12. Experimental Techniques & Chemical AnalysisIdentification of Ions & Gases

Identification of Ions & Gases (Cambridge (CIE) IGCSE Chemistry): Exam Questions

Exam code: 0620 & 0971

6 hours60 questions

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Identification of Ions & Gases

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11 mark

Which row correctly describes the test for each gas?

 

oxygen

hydrogen

chlorine

A

lighted splint pops

glowing splint relights

damp blue litmus paper turns red then white

B

 glowing splint relights

lighted splint pops

damp blue litmus paper turns red then white

C

 glowing splint relights

lighted splint pops

damp red litmus paper turns blue then white

D

lighted splint pops

glowing splint relights

damp red litmus paper turns blue then white

    Choose your answer

    21 mark

    Halide ions in solution are detected using silver nitrate solution. Dilute nitric acid is used to acidify the solution first and then a few drops of silver nitrate solution are added. Each halide produces a different coloured silver halide precipitate.

    Which row correctly describes the colour of the precipitate for each halide?

     

    chloride

    bromide

    iodide

    A

    cream

    white

    silver

    B

    yellow 

    cream

    white

    C

    white

    cream

    silver

    D

    white

    cream

    yellow

      Choose your answer

      31 mark

      A solution containing an unknown substance was analysed. On the addition of acidified silver nitrate solution a yellow precipitate formed. A flame test produced a lilac coloured flame.

      What is the identity of the unknown solid?

      • Lithium iodide

      • Lithium bromide

      • Potassium iodide

      • Potassium bromide

      Choose your answer

      41 mark

      Metal cations can be detected using flame tests.

      Which row correctly describes the colour of the flame for each metal cation?

       

      Li+

      Ba2+

      Ca2+

      A

      lilac

      green

      yellow

      B

      red

      green

      orange

      C

      green

      orange

      red

      D

      red

      blue

      orange

        Choose your answer

        51 mark

        A student tested copper sulfate solution and potassium iodide solution using flame tests using the method shown.

        1. Dip a metal wire loop in copper sulfate solution.

        2. Put the metal wire loop in a Bunsen burner flame.

        3. Record the flame colour produced.

        4. Repeat steps 1 to 3 but using potassium iodide solution.

        The student’s method did not produce the distinct lilac flame colour using potassium iodide solution.

        Which statement would not cause the lack of lilac flame?

        • The metal wire loop being overheated

        • Using the safety flame of the Bunsen burner

        • The same metal wire loop being used for each experiment

        • The metal wire loop being dipped in concentrated acid and burned between flame tests

        Choose your answer

        11 mark

        The results of two tests on a solid are shown below.

        Test

        Observation

        Acidified silver nitrate added

        Cream precipitate formed

        Aqueous sodium hydroxide added

        Red-brown precipitate formed

        What is the solid?

        • Iron(II) bromide

        • Iron(III) bromide

        • Iron(II) chloride

        • Iron(III) chloride

        Choose your answer

        21 mark

        Which reaction would result in the production of a gas that would produce a squeaky pop with a lit splint?

        • Iron(II) oxide + sulfuric acid

        • Methane + oxygen during complete combustion

        • Magnesium + hydrochloric acid

        • Carbon dioxide and water in the presence of light and chlorophyll

        Choose your answer

        31 mark

        Which statement about aqueous sodium hydroxide is correct?

        • When added to a solution containing nitrate ions and aluminium foil then warmed, the gas given off will bleach moist red litmus paper

        • When added to a solution containing iodide ions, a yellow precipitate is formed

        • When added to a solution of iron(II) ions, a green precipitate is formed which dissolves in excess sodium hydroxide to form a green solution

        • When added to a solution containing aluminium ions, a white precipitate forms which dissolves in excess sodium hydroxide to form a colourless solution

        Choose your answer

        41 mark

        The results of different chemical tests on a solution of compound Y are shown.

        Test

        Result

        Acidified barium nitrate added

        White precipitate formed

        Aqueous sodium hydroxide added

        White precipitate formed, soluble in excess

        Aqueous ammonia added

        White precipitate formed, insoluble in excess

        What is compound Y?

        • Aluminium sulfate

        • Aluminium chloride

        • Zinc sulfate

        • Zinc chloride

        Choose your answer

        51 mark

        A solution of an unknown salt is tested by adding aqueous sodium hydroxide. A blue precipitate is formed which is insoluble in excess.

        The mixture is then warmed and aluminium foil is added. A gas is released which turns damp red litmus paper blue.

        What is the salt?

        • Copper(II) nitrate

        • Copper(II) sulfate

        • Ammonium nitrate

        • Ammonium sulfate

        Choose your answer

        11 mark

        A student is given a white insoluble solid to analyse. He first added hydrochloric acid and observed bubbles of colourless gas. He then added a small amount of aqueous ammonia to the solid-acid mixture and observed a white precipitate being formed. The precipitate dissolved in excess aqueous ammonia.

        What is the identity of the white solid?

        • Ammonium nitrate

        • Aluminium nitrate

        • Zinc carbonate

        • Calcium carbonate

        Choose your answer

        21 mark

        Aqueous sodium hydroxide is used in chemical analysis.

        Which statement about aqueous NaOH is correct?

        • A white precipitate is formed when added to a solution containing sulfate ions

        • A green precipitate is formed upon addition to a solution of iron(II) ions which does not dissolve in excess

        • A green precipitate is formed upon addition to a solution of iron(II) ions which dissolves in excess

        • An acidic gas is produced when added to ammonium chloride

        Choose your answer

        31 mark

        A student analysed a solution and found it to contain ions of silver and barium. What could the identity of the anion be?

        • Nitrate

        • Sulfate

        • Chloride 

        • Carbonate

        Choose your answer

        41 mark

        A student placed a small volume of an unknown solution into two separate test tubes labelled 1 and 2. He added a few drops of aqueous NaOH to each test tube and observed a green precipitate being formed. The precipitate dissolved on the addition of excess sodium hydroxide in test 1 but the precipitate remained in test tube 2.

        Which ions must be present in test tubes 1 and 2?

         

        test tube 1

        test tube 2

        A

        Ca2+

        Cu2+

        B

        Cu2+

        Ca2+

        C

        Fe2+ 

        Cr3+

        D

        Cr3+

        Fe2+

          Choose your answer

          51 mark

          A substance produces a gas which decolourises acidified aqueous potassium manganate(VII) when warmed with dilute HCl. It produces a yellow-coloured flame in the flame test.

          What is the substance?

          • Lithium bromide

          • Potassium sulfite

          • Sodium sulfite 

          • Sodium bromide

          Choose your answer