Paper 4 style practice paper: Theory (Extended) — question paper

Section A: Structured questions[20 marks]

Answer all questions in the spaces provided. The marks for each part are shown in brackets.

1. 1

   An atom of an element contains 13 protons and 14 neutrons.

   1. (a)

      State the number of electrons in a neutral atom of this element.

      [1]
   2. (b)

      Calculate the mass number (nucleon number) of this atom.

      [1]
   3. (c)

      The element also has an isotope that contains 15 neutrons. Explain why the two atoms react in the same way.

      [1]
2. 2

   Magnesium burns in oxygen: 2Mg + O₂ → 2MgO. A student burns 4.8 g of magnesium completely in oxygen. (Aᵣ: Mg = 24, O = 16)

   1. (a)

      Calculate the number of moles of magnesium burned.

      [1]
   2. (b)

      Use the equation to deduce the number of moles of magnesium oxide formed.

      [1]
   3. (c)

      Calculate the mass of magnesium oxide formed.

      [2]
   4. (d)

      State the volume of oxygen used in this reaction at room temperature and pressure. (1 mol of any gas occupies 24 dm³.)

      [1]
3. 3

   Concentrated aqueous sodium chloride is electrolysed using inert electrodes.

   1. (a)

      Name the product formed at the cathode.

      [1]
   2. (b)

      Describe the test for this gas.

      [1]
   3. (c)

      Explain why sodium metal is not formed at the cathode.

      [2]
4. 4

   A student stirs a white solid into water and finds that the temperature of the water falls.

   1. (a)

      State whether dissolving this solid is exothermic or endothermic.

      [1]
   2. (b)

      Explain your answer in terms of energy transfer.

      [2]
   3. (c)

      State one other change that is exothermic.

      [1]
5. 5

   A student prepares copper(II) sulfate crystals by adding copper(II) oxide to warm dilute sulfuric acid.

   1. (a)

      State the type of reaction between copper(II) oxide and sulfuric acid.

      [1]
   2. (b)

      State why the copper(II) oxide is added until no more will dissolve.

      [1]
   3. (c)

      Describe how the student removes the unreacted copper(II) oxide from the mixture.

      [2]

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. The marks for each part are shown in brackets.

1. 6

   A student investigates the reaction between marble chips (calcium carbonate) and dilute hydrochloric acid by collecting the gas produced in a gas syringe and reading the volume every 30 s.

   1. (a)

      Name the gas collected.

      [1]
   2. (b)

      State one change to the marble chips that would increase the rate without changing the total volume of gas collected.

      [1]
   3. (c)

      Explain, in terms of particles and collisions, why increasing the concentration of the acid increases the rate of reaction.

      [2]
   4. (d)

      The reaction stops before all of the marble has reacted. State why.

      [1]
2. 7

   Lithium, sodium and potassium are stored under oil and all react with cold water.

   1. (a)

      Name the Group of the Periodic Table that contains these three elements.

      [1]
   2. (b)

      Explain why these metals are stored under oil.

      [1]
   3. (c)

      State and explain how the reactivity of these metals changes as you go down the Group.

      [2]
   4. (d)

      Write the word equation for the reaction between sodium and water.

      [1]
3. 8

   Ethene is produced industrially by cracking long-chain alkanes obtained from crude oil.

   1. (a)

      State the type of reaction that breaks a long-chain alkane into ethene and a shorter alkane.

      [1]
   2. (b)

      Describe the test and the result that show a gas is ethene.

      [2]
   3. (c)

      State the general formula of the alkenes.

      [1]
   4. (d)

      Name the addition polymer formed from ethene.

      [1]
4. 9

   Iron is extracted from hematite (iron(III) oxide) in a blast furnace.

   1. (a)

      Name the two substances, other than hematite and air, that are added to the blast furnace.

      [2]
   2. (b)

      Name the reducing agent that removes the oxygen from the hematite.

      [1]
   3. (c)

      State one use of the slag produced in the furnace.

      [1]
   4. (d)

      Explain why aluminium is not extracted in a blast furnace.

      [1]