St_Gabriels_2024_Prelims_4NA_Sc(Chem)_P4

St. Gabriel’s Secondary School 2024 ‘N’ Preliminary Examination Subject : Science (Chemistry) Paper No. : 5105/04 Level/Stream : Sec 4 Normal (Academic) Duration : 1 hour 15 minutes (Papers 3 and 4) Date : 07 August 2024 No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, register number and class clearly in the spaces above. Write in dark blue or black ink on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer any 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 11. 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 Paper 3 20 Paper 4 Section A 22 Section B 8 Total 50 This question paper consists of 11 printed pages including this cover page. Name: ………………………………………… ( ) Class: Sec ………………..

SGSS/Sc(Chem)/P4/4NA/Prelim/2024 2 Section A (22 marks) Answer all questions. 1 J is a mixture of dyes. It has been suggested that J might be used as a food colouring . Paper chromatography was used to identify the dyes in J. The resulting chromatograms are shown below. Dyes K, L, M and N are safe for consumption. (a) Which of the dyes K, L, M and N are present in J? ………………………….... [1] (b) Which of the dyes is insoluble in water? ………………………….... [1] (c) It is suggested that mixture J can be used as a food colouring. Do you agree with the suggestion? Use the information given to explain your answer. ……………………………………………………………………………………………………… ………………………………………………………………………………………………… [1] (d) Dye M contains two components. Suggest how you can change this chromatographic technique so as to separate these components. ………………………………………………………………………………………………… [1] [Total: 4] J K L M N

SGSS/Sc(Chem)/P4/4NA/Prelim/2024 3 2 (a) (i) Complete the table for the two isotopes of chlorine. chlorine mass number number of protons in nucleus number of neutrons in nucleus 35Cl 17 37Cl 37 20 [2] (ii) Explain why 35Cl and 37Cl a