Serangoon Prelim P2

1 SERANGOON SECONDARY SCHOOL PRELIMINARY EXAMINATION SECONDARY 4 EXPRESS CANDIDATE NAME ( ) CLASS CENTER NUMBER S INDEX NUMBER CHEMISTRY 6092/02 Paper 2 22 Aug 2024 1 hour 45 minutes Candidates answer on the Question Paper. Setter(s): READ THESE INSTRUCTIONS FIRST Write your Centre number, 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 staplers, 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 number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 27. The use of an approved scientific calculator is expected, where appropriate. This question paper consists of 26 printed pages, including this cover page. For examiner’s use Section A 70 Section B 10 9 10 Total 80

2 Section A [70 marks] Answer all questions. 1 Fig. 1.1 shows part of the Periodic Table. Li C N O A l Ca Fe Cu Zn Fig. 1.1 Select elements from Fig. 1.1 to answer the following questions. You may use each element once, more than once or not at all. Write down the symbol for an element which: (a) forms a stable ion by losing three electrons, ………………………………………………………………………………………..….…... [1] (b) exists as diatomic molecules, ………………………………………………………………………………………..….…... [1] (c) forms an ion which gives a red-brown precipitate on addition of aqueous ammonia, ………………………………………………………………………………………..….…... [1] (d) has chemical properties similar to those of magnesium, ………………………………………………………………………………………..….…... [1] (e) has a giant covalent structure, ………………………………………………………………………………………..….…... [1] (f) reacts with sodium to form an ionic compound with Mr less than 70. ………………………………………………………………………………………..….…... [1] [Total: 6]

3 2 A laboratory technician mixes red, blue and yellow dyes to make black dye for a paper chromatography experiment. A common solvent used to separate the dyes in black ink is a mixture of ethanol and water. The coloured dyes have different Rf values in solvents with different composition of ethanol as shown in Fig. 2.1. Fig. 2.1 (a) Predict the colours of the separated spots observed when the solvent used consists of 40% ethanol in the mixture. ………………………………………………………………………………………..….….. [1] (b) State the Rf value of the yellow dye on the chromatogram when the solvent is a mixture of 64 cm3 of ethanol and 136 cm3 of water. ………………………………………………………………………………………..….….. [1] (c) Explain why a pure solvent of water or ethanol is not suitable for the separation of t