Temasek 2024_Prelim_Sec 4E Chemistry P2 & MS

St. Gabriel’s Secondary School 2024 ‘O’ Preliminary Examination Subject : Chemistry Paper : 6092 / 02 Level/Stream : Secondary 4 (Express) Duration : 1 hour 45 minutes Date : 21 August 2024 No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class 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 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 24. The use of an approved scientific calculator is expected, where appropriate. 2023_EYE_Sec 3N Science (Chemistry) FOR EXAMINER’S USE Section A 70 Section B 10 TOTAL 80 This question paper consists of 24 printed pages. Name: …………………………………………………… ( ) Class: Sec ………………..

2 SGSS/Chemistry/P2/4E/Prelim/2024 Section A Answer all questions. 1 Fig. 1.1 shows part of the Periodic Table. The elements are represented by the letters M, Q, R, T, W, X, Y and Z. Y R W X Z M T Q Fig. 1.1 Select elements from the Periodic Table to answer the following questions. You may use each element once, more than once or not at all. (a) Which two elements react together most vigorously? ………………………………………………………………………………………………….. [1] (b) Which element forms an ion with a charge of –2? ………………………………………………………………………………………………….. [1] (c) Which element has a high density? ………………………………………………………………………………………………….. [1] (d) What is the formula of the compound formed when W reacts with Y? ………………………………………………………………………………………………….. [1] (e) Which element constitutes about 1% of dry air? ………………………………………………………………………………………………….. [1] [Total: 5]

3 SGSS/Chemistry/P2/4E/Prelim/2024 2 Sodium carbonate ionises in water according to the following equation. Na2CO3(s) + H2O(l) ⇌ 2Na+(aq) + HCO3–(aq) + OH–(aq) Fig. 2.1 shows the effect of pressure and temperature on the concentration of hydroxide ions produced per mole of sodium carbonate. concentration of OH– ions pressure Fig. 2.1 (a) (i) Sodium carbonate is a weak alkali. Explain what a weak alkali is. ………………………………………………………………………………………………….. …………………………………………………………………………………………… [1] (ii) State the colour of the resulting mixture when a few drops of Universal Indicator are added to a solution of sodium carbonate. …………………………………………………………………………………………… [1] (b) (i) Describe how te