Bowen Prelim 4NA Sc(c) P4 2025 final

Class Full Name Index Number PRELIMINARY EXAMINATION 2025 I believe, therefore I am SCIENCE (CHEMISTRY) Paper 4 Secondary 4 Normal Academic Papers 3 and 4: 1 hour 15 minutes Candidates answer on the Question Paper No Additional Materials are required. 30 July 2025 READ THESE INSTRUCTIONS FIRST Write your class, index number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. The use of an approved scientific calculator is expected, where appropriate. In calculations, you should show all the steps in your working, giving your answer at each stage. You are advised to spend no longer than 30 minutes on Paper 3. You may proceed to answer Paper 4 as soon as you have completed Paper 3. A copy of the Periodic Table is printed on page 12. At the end of the examination hand in your answers to Paper 3 and Paper 4 separately. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A / 22 Section B B……..... / 8 Total This document consists of 11 printed pages, including the cover page and 1 blank page. 30 N 5105/5107/04

2 [Turn over Section A Answer all questions. A1 Choose from the substances listed to answer the questions. calcium hydroxide sodium hydroxide calcium chloride carbon dioxide ammonia hydrogen oxygen water neon Each substance may be used once, more than once or not at all. Identify the substance which (a) extinguishes a lighted splint with a ‘pop’ sound …………………………………………………………………………………………….. [1] (b) is an unreactive element …………………………………………………………………………………………….. [1] (c) is added to soil to control its acidity. …………………………………………………………………………………………….. [1] [Total:3] For Examiner’s Use

3 [Turn over A2 A compound Y contains only carbon and hydrogen. The diagram shows the bonding in Y. Only the outer electrons are shown for each atom. (a) Name compound Y. …………………………………………………………………………………………….. [1] (b) State the type of bonding present in Y. …………………………………………………………………………………………….. [1] (c) Compound Y can be used as a fuel. Name the gas produced when Y burns in a limited supply of air. …………………………………………………………………………………………….. [1] (d) Hydrogen, H 2, can also be burned as a fuel. Explain why it is less harmful to the environment to burn hydrogen than compound Y. ………………………………………………………………………………………………… …………………………………………………………………………………………….. [1] [Total:4] A3 Alkenes are a homologous series of unsaturated hydrocarbons. (a) State the general formula of alkenes. ……………………………………………………………………………………………... [1] (b) In addition to having a general formula, state another characteristic of compounds in the same homologous series. ……………………………………………………………………………………………... [1] For Examiner’s Use

4 [Turn over (c) Ethene reacts with bromine under room conditions. (i) Name this type of reaction. …………………………………………………………………………………………. [1] (ii) Complete the following equation to show the full structural formula of the product formed in this reaction. [1] (iii) State the colour change of the reaction mixture in (ii). The colour changes from …………………...… to ………..………………. [1] (iv) Besides ethene, ethane can also react with bromine. State a condition required for this to happen. …………………………………………………………………………………………. [1] (v) Write the balanced chemical equation for the complete combustion of ethene, state symbols are not required. …………………………………………………………………………………………. [1] [Total: 7] A4 A student attempts to determine the percentage of oxygen in the air using the apparatus shown. At the start of the experiment there is 90 cm 3 of air in the apparatus. The air is passed backwards and forwards between gas syringes F and G over the heated magnesium. magnesium For Examiner’s Use

5 [Turn over This is repeated until the volume stops decreasing. The gas is allowed to cool to room temperature and the final volume is measured. The magnesium reacts with the oxygen in the air to produce solid magnesium oxide. An excess of magnesium is used to ensure all the oxygen in the air is reacted. (a) Name two gases that are present in the final volume of gas after all oxygen has reacted. 1 ………………………………………… 2 ………………………………………… [2] (b) State the electronic configuration of an oxygen atom. …………………………………………………………………………………………….. [1] (c) Draw a ‘dot-and-cross’ diagram to show the bonding present in magnesium oxide. Show only the outer-shell electrons. [2] (d) The student repeats the experiment several times using different initial volumes of air in the apparatus. An excess of magnesium is used in each experiment. The results are shown in the table. initial volume of air / cm3 final volume of gas / cm3 90 71 70 55 60 47 50 39 40 31 20 16 For Examiner’s Use

6 [Turn over Plot a graph of the final volume of gas against the initial volume of air. Mark each point with a cross (x). Draw a line of best fit taking into account all your plotted points. [2] (e) Use your graph to determine the final volume of gas if the student uses 80 cm3 as the initial volume of air. answer ………………………. cm3 [1] [Total: 8] For Examiner’s Use

7 [Turn over Section B Answer one question from this section. B1 (a) A student wants to separate the coloured pigments in a plant leaf by chromatography. The student grinds the plant leaf and separates the solids from the green solution. Identify the method used to separate the solids from the green solution. ………………………………………………………………………………………..……. [1] (b) The student sets up the chromatography apparatus shown. The student made two mistakes. One mistake was to add too much solvent so that the start line was in the solvent. (i) Explain why this mistake would not lead to the separation of coloured pigments. …………………………………………………………………………………………… ………………………………………………………………………………………… [1] (ii) Identify the second mistake and suggest how this mistake would be corrected. mistake ……………………………………………………………………………….. correction …………………………………………………………………………….. [1] The mistakes were corrected, and the final chromatogram is shown. (iii) State the number of differ