WA1 Practice Paper: Weighted Assessment 1 — question paper

Section A: Multiple-choice questions[10 marks]

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

1. 1

   In the reaction CuO + H₂ → Cu + H₂O, the substance reduced is

   1. ACuO, because it loses oxygen
   2. BH₂, because it gains oxygen
   3. CCu, because it turns brown
   4. DH₂O, because it is a product
   ( )
2. 2

   In terms of electrons, oxidation is

   1. Again of electrons
   2. Bgain of protons
   3. Closs of neutrons
   4. Dloss of electrons
   ( )
3. 3

   The oxidation state of sulfur in sulfuric acid, H₂SO₄, is (H = +1, O = −2)

   1. A+4
   2. B+6
   3. C−2
   4. D+2
   ( )
4. 4

   Acidified potassium manganate(VII) loses its purple colour when shaken with a solution. The solution contains

   1. Aan oxidising agent
   2. Ba catalyst
   3. Cwater only
   4. Da reducing agent
   ( )
5. 5

   Elements in the same group of the Periodic Table have the same

   1. Anumber of protons
   2. Bnumber of occupied shells
   3. Cnumber of outer-shell electrons
   4. Drelative atomic mass
   ( )
6. 6

   Going down Group 17 from chlorine to bromine to iodine, the elements become

   1. Amore reactive and darker in colour
   2. Bless reactive and darker in colour
   3. Cmore reactive and lighter in colour
   4. Dunchanged in reactivity
   ( )
7. 7

   Chlorine water is added to aqueous potassium bromide. The observation is

   1. Ano change, chlorine is less reactive
   2. Bwhite fumes form
   3. Cthe mixture turns purple
   4. Dthe solution turns orange-brown as bromine is displaced
   ( )
8. 8

   The most reactive metal in the list K, Na, Ca, Mg, Cu is

   1. AK
   2. BNa
   3. CCa
   4. DCu
   ( )
9. 9

   Iron rusts only when it is in contact with

   1. Awater alone
   2. Boxygen alone
   3. Cboth oxygen and water
   4. Dcarbon dioxide and water
   ( )
10. 10

    Painting an iron gate prevents rusting by

    1. Amaking the iron purer
    2. Bkeeping out oxygen and water
    3. Cadding oxygen slowly
    4. Dturning the iron into steel
    ( )

Section B: Structured questions[30 marks]

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

1. 1

   Hydrogen reduces hot copper(II) oxide: CuO + H₂ → Cu + H₂O.

   1. (a)

      State which substance is oxidised and which is reduced, in terms of oxygen transfer.

      [2]
   2. (b)

      Write the half-equation showing the reduction of Cu²⁺ ions.

      [2]
   3. (c)

      Identify the oxidising agent in the reaction and explain the term.

      [2]
2. 2

   The table shows the electron arrangements of four elements.

   Electron arrangements

   Element	Electron arrangement
   W	2.8.1
   X	2.8.7
   Y	2.8.8.1
   Z	2.8.8.7

   1. (a)

      State which two elements are in the same group of the Periodic Table, and give the group number.

      [2]
   2. (b)

      One of W and Y reacts more vigorously with water than the other. State which, and explain using the Group I trend.

      [2]
   3. (c)

      Predict the formula of the compound formed between W and X, explaining how you used the electron arrangements.

      [2]
3. 3

   Pieces of metal are dropped into solutions of salts of other metals. The results are: magnesium changes the colour of copper(II) sulfate solution; copper makes no change in magnesium sulfate solution; magnesium makes no change in zinc sulfate solution.

   1. (a)

      Arrange Mg, Cu and Zn in order of reactivity, most reactive first, explaining how the results justify each step.

      [4]
   2. (b)

      Write the ionic equation for the reaction between magnesium and copper(II) sulfate, including state symbols.

      [2]
4. 4

   An iron nail is set up in three tubes for two weeks: tube 1 with plain water open to the air; tube 2 with boiled water topped by oil; tube 3 with dry air and a drying agent.

   1. (a)

      State and explain the appearance of the nail in each tube.

      [3]
   2. (b)

      State the conclusion of the experiment.

      [1]
   3. (c)

      Name one method of preventing rusting other than painting, and say how it works.

      [2]
5. 5

   A student investigates redox reactions with three solutions: potassium iodide, acidified potassium manganate(VII) and iron(II) sulfate.

   1. (a)

      Describe what is observed when potassium iodide solution is mixed with acidified potassium manganate(VII), and name the type of change each substance undergoes.

      [4]
   2. (b)

      Explain why iron(II) sulfate also decolourises acidified potassium manganate(VII), naming the role of the iron(II) ions.

      [2]