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EOY Practice Paper: End-of-Year Examination — question paper

QuizQuipPractice Series
QQ/S3CCH/EOY

Secondary 3 · Combined Science (Chemistry) (G2 / G3)

EOY Practice Paper

End-of-Year Examination

Duration: 90 minutes
Total: 60 marks
Name:
Class:
Register No.:
Date:

READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A: choose the one correct answer for each multiple-choice question.
  • Section B: answer in the spaces provided; show all necessary working.
  • Give numerical answers to 3 significant figures where appropriate, with units.
  • A copy of the Periodic Table is printed with real Combined Science papers; it is not needed for this paper.
  • The use of a calculator is permitted.

Original practice material written for the MOE Combined Science (Chemistry) syllabus. It is not an official MOE or school examination paper. The full Sec 3 year: experimental chemistry and purification; particulate nature of matter; chemical bonding and structure; chemical calculations; acid–base chemistry; qualitative analysis.

For Examiner’s Use
Section A/ 20
Section B/ 40
Total/ 60

Section A: Multiple-choice questions[20 marks]

Answer all questions. For each question, write the letter (A, B, C or D) of the correct answer.

  1. 1

    Dry crystals of copper(II) sulfate are obtained from its solution by

    1. Afiltering and drying the residue
    2. Bevaporating all the water strongly, then sweeping the powder
    3. Cheating to crystallisation point, cooling, then drying the crystals
    4. Ddistilling the solution and collecting the distillate
    ( )
  2. 2

    Hydrogen is insoluble in water and much less dense than air. It is collected by

    1. Adownward delivery (upward displacement of air)
    2. Bupward delivery (downward displacement of air)
    3. Ca gas syringe only
    4. Dnone of these
    ( )
  3. 3

    A solid melts sharply at exactly one temperature. This shows the solid is

    1. Aa pure substance
    2. Ba mixture
    3. Can alloy
    4. Dstill wet
    ( )
  4. 4

    In a liquid, the particles

    1. Avibrate about fixed positions only
    2. Bare far apart and move randomly at high speed
    3. Cslide and tumble past one another while staying close together
    4. Dstop moving at low temperature
    ( )
  5. 5

    The ion ⁴⁰₂₀Ca²⁺ contains how many electrons?

    1. A20
    2. B22
    3. C18
    4. D40
    ( )
  6. 6

    Chlorine-35 and chlorine-37 differ in their number of

    1. Aprotons
    2. Bneutrons
    3. Celectrons
    4. Dprotons and electrons
    ( )
  7. 7

    In a dot-and-cross diagram of a water molecule, the number of shared pairs of electrons is

    1. A2
    2. B4
    3. C8
    4. D1
    ( )
  8. 8

    Which substance exists as simple molecules?

    1. Asodium chloride
    2. Bcarbon dioxide
    3. Ccopper
    4. Dbrass
    ( )
  9. 9

    Brass, used in musical instruments, is

    1. Aa mixture of copper and zinc
    2. Ba compound of copper and zinc
    3. Ca pure metal
    4. Dan ionic solid
    ( )
  10. 10

    Metals conduct electricity in the solid state because

    1. Atheir atoms carry charges
    2. Btheir electrons are free to move through the lattice
    3. Ctheir ions move quickly
    4. Dthey contain water
    ( )
  11. 11

    The relative molecular mass of nitric acid, HNO₃, is (H = 1, N = 14, O = 16)

    1. A31
    2. B47
    3. C63
    4. D79
    ( )
  12. 12

    The number of moles in 4.4 g of carbon dioxide, CO₂, is (C = 12, O = 16)

    1. A0.1 mol
    2. B0.2 mol
    3. C4.4 mol
    4. D10 mol
    ( )
  13. 13

    The volume occupied by 0.25 mol of oxygen gas at room temperature and pressure is

    1. A0.25 dm³
    2. B24 dm³
    3. C1.5 dm³
    4. D6.0 dm³
    ( )
  14. 14

    In the reaction 2Mg + O₂ → 2MgO, the moles of MgO formed from 3 mol of magnesium are

    1. A1.5 mol
    2. B3 mol
    3. C6 mol
    4. D2 mol
    ( )
  15. 15

    Universal indicator turns red in solution X. Solution X is

    1. Aa strongly acidic solution
    2. Ba strongly alkaline solution
    3. Cneutral
    4. Dpure water
    ( )
  16. 16

    A metal is added to dilute hydrochloric acid and a gas burns with a squeaky pop. The gas is

    1. Acarbon dioxide
    2. Boxygen
    3. Chydrogen
    4. Dchlorine
    ( )
  17. 17

    The ionic equation for any acid–alkali neutralisation is

    1. AH₂ + O₂ → H₂O
    2. BH⁺(aq) + OH⁻(aq) → H₂O(l)
    3. CH⁺(aq) + Cl⁻(aq) → HCl(aq)
    4. DNa⁺(aq) + OH⁻(aq) → NaOH(aq)
    ( )
  18. 18

    Which oxide reacts with both acids and alkalis?

    1. ACO₂
    2. BCaO
    3. CCuO
    4. DZnO
    ( )
  19. 19

    A white precipitate forms with sodium hydroxide solution and is insoluble in excess. The cation is

    1. AAl³⁺
    2. BCa²⁺
    3. CCu²⁺
    4. DFe³⁺
    ( )
  20. 20

    A gas is bubbled through limewater, which turns milky. The gas is

    1. Ahydrogen
    2. Boxygen
    3. Cammonia
    4. Dcarbon dioxide
    ( )

Section B: Structured questions[40 marks]

Answer all questions in the spaces provided. Show all necessary working.

  1. 1

    A student separates the coloured dyes in a black food colouring by paper chromatography, running pure dyes A and B on the same sheet. The black colouring separates into three spots: two matching A and B, and one that matches neither.

    1. (a)

      Describe how the student carries out the chromatography, including one safety precaution about the solvent.

      [4]
    2. (b)

      State what the chromatogram shows about the black colouring.

      [2]
    3. (c)

      Explain why the dyes separate into different positions.

      [2]
    4. (d)

      State one way to show a dye spot is the same substance as a spot in another sample.

      [2]
  2. 2

    This question is about bonding.

    1. (a)

      Draw a dot-and-cross diagram for a molecule of carbon dioxide, showing outer-shell electrons only. (Carbon: proton number 6; oxygen: proton number 8.)

      [3]
    2. (b)

      Explain why carbon dioxide has a very low boiling point even though its covalent bonds are strong.

      [3]
    3. (c)

      Steel is an alloy of iron with carbon. Explain, using the lattice, why alloys are harder than pure metals.

      [4]
  3. 3

    Ethene burns in oxygen: C₂H₄ + 3O₂ → 2CO₂ + 2H₂O. (H = 1, C = 12, O = 16; gas molar volume = 24 dm³ at r.t.p.)

    1. (a)

      Calculate the relative molecular mass of ethene, C₂H₄.

      [1]
    2. (b)

      Calculate the number of moles in 5.6 g of ethene.

      moles =[2]
    3. (c)

      Calculate the moles of carbon dioxide produced when all 5.6 g of ethene burns.

      moles =[2]
    4. (d)

      Calculate the volume of the carbon dioxide produced at r.t.p.

      volume =dm³[2]
    5. (e)

      State the volume of oxygen needed for the complete combustion of 5.6 g of ethene.

      volume =dm³[3]
  4. 4

    A colourless solution X is tested.

    Test results for solution X

    TestObservation
    add dilute hydrochloric acida gas is released that turns limewater milky
    add sodium hydroxide solution and warm gentlya gas is released that turns damp red litmus paper blue
    add acidified silver nitrate solutionno reaction
    1. (a)

      Identify the gas in test 1 and the anion it proves X contains.

      [3]
    2. (b)

      Identify the gas in test 2 and the cation it proves X contains. Write the ionic equation for the gas forming.

      [4]
    3. (c)

      What does test 3 show about X? Give a reason.

      [1]
    4. (d)

      Write the chemical formula of X.

      [2]

— End of paper —